Reactivity 3. What are the mechanisms of chemical change?

Enzymatic activity is studied in buffered aqueous solutions.

Calculate the ratio in which 0.1 mol dm⁻³ NaH₂PO₄ (aq) and 0.1 mol dm⁻³ Na₂HPO₄ (aq) should be mixed to obtain a buffer with pH = 6.10. Use section 1 of the data booklet.

pK_a (NaH₂PO₄) = 7.20

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Which species are acids in the equilibrium below?

CH₃NH₂ + H₂O $\rightleftharpoons$ CH₃NH₃⁺ + OH^–

A.  CH₃NH₂ and H₂O

B.  H₂O and CH₃NH₃⁺

C.  H₂O and OH^–

D.  CH₃NH₂ and CH₃NH₃⁺

Which solution is basic at 25 °C?

K_w = 1.0 × 10⁻¹⁴

A. [H⁺] = 1.0 × 10⁻³ mol dm⁻³

B. [OH⁻] = 1.0 × 10⁻¹³ mol dm⁻³

C. solution of pH = 4.00

D. [H₃O⁺] = 1.0 × 10⁻¹³ mol dm⁻³

Which has the strongest conjugate base?

A. HCOOH (K_a = 1.8 × 10⁻⁴)

B. HNO₂ (K_a = 7.2 × 10⁻⁴)

C. HCN (K_a = 6.2 × 10⁻¹⁰)

D. HIO₃ (K_a = 1.7 × 10⁻¹)

What happens to the amount of hydroxide ions and hydroxide ion concentration when water is added to a solution of NH₃(aq)?

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid:

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

Calculate the pH of a 1.00 × 10⁻² mol dm⁻³ aqueous solution of ammonia.

pK_b = 4.75 at 298 K.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid: 

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

At 298 K the concentration of aqueous carbon dioxide in carbonated water is 0.200 mol dm⁻³ and the pK_a for Equilibrium (2) is 6.36.

Calculate the pH of carbonated water.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Aqueous sodium hydrogencarbonate has a pH of approximately 7 at 298 K.

Sketch a graph of pH against volume when 25.0cm³ of 0.100 mol dm⁻³ NaOH (aq) is gradually added to 10.0cm³ of 0.0500 mol dm⁻³ NaHCO₃ (aq).

Some antacids contain carbonates.

Determine the pH of a buffer solution which contains 0.160 mol dm⁻³ CO₃²⁻ and 0.200 mol dm⁻³ HCO₃⁻, using section 1 of the data booklet.

pK_a (HCO₃⁻) = 10.32

Outline why ethanoic acid is classified as a weak acid.

Where is the buffer region for the titration of a weak acid with a strong base?

Describe, using a suitable equation, how the buffer solution formed during the titration resists pH changes when a small amount of acid is added.

Some antacids contain carbonates.

Determine the pH of a buffer solution which contains 0.160 mol dm⁻³ CO₃²⁻ and 0.200 mol dm⁻³ HCO₃⁻, using section 1 of the data booklet.

pK_a (HCO₃⁻) = 10.32

What is the pH of 0.001 mol dm⁻³ NaOH (aq)?

A. 1

B. 3

C. 11

D. 13

What is the pH of 0.001 mol dm⁻³ NaOH (aq)?

A. 1

B. 3

C. 11

D. 13

Which solution is basic at 25 °C?

K_w = 1.0 × 10⁻¹⁴

A. [H⁺] = 1.0 × 10⁻³ mol dm⁻³

B. [OH⁻] = 1.0 × 10⁻¹³ mol dm⁻³

C. solution of pH = 4.00

D. [H₃O⁺] = 1.0 × 10⁻¹³ mol dm⁻³

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Draw the structure of the conjugate base of benzoic acid showing all the atoms and all the bonds.

The pH of an aqueous solution of benzoic acid at 298 K is 2.95. Determine the concentration of hydroxide ions in the solution, using section 2 of the data booklet.

An additional experiment was conducted in which only the sulfuric acid catalyst was titrated with $\mathrm{NaOH}\hspace{0.17em}\left(\mathrm{aq}\right)$. Outline why this experiment was necessary.

The following equation represents the dissociation of water at 25 °C.

2H₂O (l) $\rightleftharpoons$ H₃O⁺ (aq) + OH⁻ (aq)        ΔH = +56 kJ

Which changes occur as the temperature increases?

A. [H₃O⁺] increases and pH will decrease.

B. [H₃O⁺] decreases and pH will increase.

C. [H₃O⁺] increases and pH will increase.

D. [H₃O⁺] decreases and pH will decrease.

Saturated calcium hydroxide solution is used to test for carbon dioxide. Calculate the pH of a 2.33 × 10⁻²mol dm⁻³ solution of calcium hydroxide, a strong base.

Which is a Lewis acid, but not a Brønsted-Lowry acid?

A.  ${\text{BF}}_3$

B.  ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$

C.  ${\text{NH}}_3$

D.  ${\text{Cl}}^{-}$

With which do most acids react?

   I. sodium hydrogen carbonate
   II. magnesium
   III. calcium sulfate

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

Saturated aqueous hydrogen sulfide has a concentration of 0.10 mol dm⁻³ and a pH of 4.0. Demonstrate whether it is a strong or weak acid.

Which of these acids has the weakest conjugate base?

A.  $\mathrm{HCl}$

B.  ${\mathrm{CH}}_3\mathrm{COOH}$

C.  ${\mathrm{NH}}_4\mathrm{Cl}$

D.  ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}$

What is the pH of an ammonia solution that has $\left[{\mathrm{OH}}^{-}\right]=1\times {10}^{-4} \mathrm{mol} {\mathrm{dm}}^{-3}$?

A.  $4.0$

B.  $8.0$

C.  $10.0$

D.  $12.0$

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

Which solution has a pH of 9?

A.  1.0 × 10⁻⁹ mol dm⁻³ $\text{HCl}$ (aq)

B.  1.0 × 10⁻⁵ mol dm⁻³ $\text{KOH}$ (aq)

C.  1.0 × 10⁻⁹ mol dm⁻³ $\text{KOH}$ (aq)

D.  1.0 × 10⁻⁵ mol dm⁻³ $\text{HCl}$ (aq)

Which of the 0.001 mol dm⁻³ solutions is most likely to have a pH of 11.3?

A.  Ca(OH)₂(aq)

B.  H₃PO₄(aq)

C.  NaOH (aq)

D.  NH₄OH (aq)

What is the pH of 0.01 mol dm⁻³ KOH (aq)?

A.  1.0

B.  2.0

C.  12.0

D.  13.0

Calculate the initial pH before any sodium hydroxide was added, using section 21 of the data booklet.

The concentration of excess sodium hydroxide was 0.362 mol dm⁻³. Calculate the pH of the solution at the end of the experiment.

Sketch the neutralisation curve obtained and label the equivalence point.

Which homologous series has the general formula C_nH_2nO (n > 2)?

A.  Alcohols

B.  Carboxylic acids

C.  Ethers

D.  Ketones

Which conditions best favour oxidation of primary alcohols directly to carboxylic acids?

A.  Excess acidified potassium dichromate (VI) and distillation

B.  Excess acidified potassium dichromate (VI) and reflux

C.  Few drops of acidified potassium dichromate (VI) and distillation

D.  Few drops of acidified potassium dichromate (VI) and reflux

Which solutions will form a buffer when mixed?

A.  50 cm³ of 1.0 mol dm⁻³ HCl and 50 cm³ of 1.0 mol dm⁻³ NaOH

B.  50 cm³ of 1.0 mol dm⁻³ CH₃COOH and 50 cm³ of 1.0 mol dm⁻³ NaOH

C.  50 cm³ of 1.0 mol dm⁻³ CH₃COOH and 100 cm³ of 1.0 mol dm⁻³ NaOH

D.  100 cm³ of 1.0 mol dm⁻³ CH₃COOH and 50 cm³ of 1.0 mol dm⁻³ NaOH

Which of the following statements is correct when a 1.0 M NH₄+/NH₃ buffer (pH = 9.2) is diluted to 0.5 M with water?

I.    The ability of the buffer to resist changes in pH when acids are added will decrease.

II.  The ability of the buffer to resist changes in pH when bases are added will decrease.

III. The pH of the buffer will be equal to 7.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Determine the ratio in which 0.1 mol dm^–3 NaH₂PO₄ and 0.1 mol dm^–3 Na₂HPO₄ should be mixed to obtain a buffer with pH= 7.8.

pK_a NaH₂PO₄ = 7.20

Enzymatic activity is studied in buffered aqueous solutions.

Calculate the ratio in which 0.1 mol dm⁻³ NaH₂PO₄ (aq) and 0.1 mol dm⁻³ Na₂HPO₄ (aq) should be mixed to obtain a buffer with pH = 6.10. Use section 1 of the data booklet.

pK_a (NaH₂PO₄) = 7.20

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Which species are acids in the equilibrium below?

CH₃NH₂ + H₂O $\rightleftharpoons$ CH₃NH₃⁺ + OH^–

A.  CH₃NH₂ and H₂O

B.  H₂O and CH₃NH₃⁺

C.  H₂O and OH^–

D.  CH₃NH₂ and CH₃NH₃⁺

Which solution is basic at 25 °C?

K_w = 1.0 × 10⁻¹⁴

A. [H⁺] = 1.0 × 10⁻³ mol dm⁻³

B. [OH⁻] = 1.0 × 10⁻¹³ mol dm⁻³

C. solution of pH = 4.00

D. [H₃O⁺] = 1.0 × 10⁻¹³ mol dm⁻³

Which has the strongest conjugate base?

A. HCOOH (K_a = 1.8 × 10⁻⁴)

B. HNO₂ (K_a = 7.2 × 10⁻⁴)

C. HCN (K_a = 6.2 × 10⁻¹⁰)

D. HIO₃ (K_a = 1.7 × 10⁻¹)

What happens to the amount of hydroxide ions and hydroxide ion concentration when water is added to a solution of NH₃(aq)?

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid:

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid:

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

Calculate the pH of a 1.00 × 10⁻² mol dm⁻³ aqueous solution of ammonia.

pK_b = 4.75 at 298 K.

Calculate the pH of a 1.00 × 10⁻² mol dm⁻³ aqueous solution of ammonia.

pK_b = 4.75 at 298 K.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid: 

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

At 298 K the concentration of aqueous carbon dioxide in carbonated water is 0.200 mol dm⁻³ and the pK_a for Equilibrium (2) is 6.36.

Calculate the pH of carbonated water.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Aqueous sodium hydrogencarbonate has a pH of approximately 7 at 298 K.

Sketch a graph of pH against volume when 25.0cm³ of 0.100 mol dm⁻³ NaOH (aq) is gradually added to 10.0cm³ of 0.0500 mol dm⁻³ NaHCO₃ (aq).

Distinguish between a weak and strong acid.

Weak acid: 

Strong acid: 

The hydrogencarbonate ion, produced in Equilibrium (2), can also act as an acid.

State the formula of its conjugate base.

At 298 K the concentration of aqueous carbon dioxide in carbonated water is 0.200 mol dm⁻³ and the pK_a for Equilibrium (2) is 6.36.

Calculate the pH of carbonated water.

Predict, referring to Equilibrium (2), how the added sodium hydrogencarbonate affects the pH.(Assume pressure and temperature remain constant.)

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Aqueous sodium hydrogencarbonate has a pH of approximately 7 at 298 K.

Sketch a graph of pH against volume when 25.0cm³ of 0.100 mol dm⁻³ NaOH (aq) is gradually added to 10.0cm³ of 0.0500 mol dm⁻³ NaHCO₃ (aq).

Some antacids contain carbonates.

Determine the pH of a buffer solution which contains 0.160 mol dm⁻³ CO₃²⁻ and 0.200 mol dm⁻³ HCO₃⁻, using section 1 of the data booklet.

pK_a (HCO₃⁻) = 10.32

Outline why ethanoic acid is classified as a weak acid.

Outline why ethanoic acid is classified as a weak acid.

Where is the buffer region for the titration of a weak acid with a strong base?

Describe, using a suitable equation, how the buffer solution formed during the titration resists pH changes when a small amount of acid is added.

Describe, using a suitable equation, how the buffer solution formed during the titration resists pH changes when a small amount of acid is added.

Some antacids contain carbonates.

Determine the pH of a buffer solution which contains 0.160 mol dm⁻³ CO₃²⁻ and 0.200 mol dm⁻³ HCO₃⁻, using section 1 of the data booklet.

pK_a (HCO₃⁻) = 10.32

What is the pH of 0.001 mol dm⁻³ NaOH (aq)?

A. 1

B. 3

C. 11

D. 13

What is the pH of 0.001 mol dm⁻³ NaOH (aq)?

A. 1

B. 3

C. 11

D. 13

Which solution is basic at 25 °C?

K_w = 1.0 × 10⁻¹⁴

A. [H⁺] = 1.0 × 10⁻³ mol dm⁻³

B. [OH⁻] = 1.0 × 10⁻¹³ mol dm⁻³

C. solution of pH = 4.00

D. [H₃O⁺] = 1.0 × 10⁻¹³ mol dm⁻³

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Formulate an equation for the reaction of one mole of phosphoric acid with one mole of sodium hydroxide.

Draw the structure of the conjugate base of benzoic acid showing all the atoms and all the bonds.

The pH of an aqueous solution of benzoic acid at 298 K is 2.95. Determine the concentration of hydroxide ions in the solution, using section 2 of the data booklet.

Draw the structure of the conjugate base of benzoic acid showing all the atoms and all the bonds.

The pH of an aqueous solution of benzoic acid at 298 K is 2.95. Determine the concentration of hydroxide ions in the solution, using section 2 of the data booklet.

An additional experiment was conducted in which only the sulfuric acid catalyst was titrated with $\mathrm{NaOH}\hspace{0.17em}\left(\mathrm{aq}\right)$. Outline why this experiment was necessary.

The following equation represents the dissociation of water at 25 °C.

2H₂O (l) $\rightleftharpoons$ H₃O⁺ (aq) + OH⁻ (aq)        ΔH = +56 kJ

Which changes occur as the temperature increases?

A. [H₃O⁺] increases and pH will decrease.

B. [H₃O⁺] decreases and pH will increase.

C. [H₃O⁺] increases and pH will increase.

D. [H₃O⁺] decreases and pH will decrease.

Saturated calcium hydroxide solution is used to test for carbon dioxide. Calculate the pH of a 2.33 × 10⁻²mol dm⁻³ solution of calcium hydroxide, a strong base.

Saturated calcium hydroxide solution is used to test for carbon dioxide. Calculate the pH of a 2.33 × 10⁻²mol dm⁻³ solution of calcium hydroxide, a strong base.

Which is a Lewis acid, but not a Brønsted-Lowry acid?

A.  ${\text{BF}}_3$

B.  ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$

C.  ${\text{NH}}_3$

D.  ${\text{Cl}}^{-}$

With which do most acids react?

   I. sodium hydrogen carbonate
   II. magnesium
   III. calcium sulfate

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

Saturated aqueous hydrogen sulfide has a concentration of 0.10 mol dm⁻³ and a pH of 4.0. Demonstrate whether it is a strong or weak acid.

Saturated aqueous hydrogen sulfide has a concentration of 0.10 mol dm⁻³ and a pH of 4.0. Demonstrate whether it is a strong or weak acid.

Which of these acids has the weakest conjugate base?

A.  $\mathrm{HCl}$

B.  ${\mathrm{CH}}_3\mathrm{COOH}$

C.  ${\mathrm{NH}}_4\mathrm{Cl}$

D.  ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}$

What is the pH of an ammonia solution that has $\left[{\mathrm{OH}}^{-}\right]=1\times {10}^{-4} \mathrm{mol} {\mathrm{dm}}^{-3}$?

A.  $4.0$

B.  $8.0$

C.  $10.0$

D.  $12.0$

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

Which solution has a pH of 9?

A.  1.0 × 10⁻⁹ mol dm⁻³ $\text{HCl}$ (aq)

B.  1.0 × 10⁻⁵ mol dm⁻³ $\text{KOH}$ (aq)

C.  1.0 × 10⁻⁹ mol dm⁻³ $\text{KOH}$ (aq)

D.  1.0 × 10⁻⁵ mol dm⁻³ $\text{HCl}$ (aq)

Which of the 0.001 mol dm⁻³ solutions is most likely to have a pH of 11.3?

A.  Ca(OH)₂(aq)

B.  H₃PO₄(aq)

C.  NaOH (aq)

D.  NH₄OH (aq)

What is the pH of 0.01 mol dm⁻³ KOH (aq)?

A.  1.0

B.  2.0

C.  12.0

D.  13.0

Calculate the initial pH before any sodium hydroxide was added, using section 21 of the data booklet.

The concentration of excess sodium hydroxide was 0.362 mol dm⁻³. Calculate the pH of the solution at the end of the experiment.

Sketch the neutralisation curve obtained and label the equivalence point.

Calculate the initial pH before any sodium hydroxide was added, using section 21 of the data booklet.

The concentration of excess sodium hydroxide was 0.362 mol dm⁻³. Calculate the pH of the solution at the end of the experiment.

Sketch the neutralisation curve obtained and label the equivalence point.

Which homologous series has the general formula C_nH_2nO (n > 2)?

A.  Alcohols

B.  Carboxylic acids

C.  Ethers

D.  Ketones

Which conditions best favour oxidation of primary alcohols directly to carboxylic acids?

A.  Excess acidified potassium dichromate (VI) and distillation

B.  Excess acidified potassium dichromate (VI) and reflux

C.  Few drops of acidified potassium dichromate (VI) and distillation

D.  Few drops of acidified potassium dichromate (VI) and reflux

Which solutions will form a buffer when mixed?

A.  50 cm³ of 1.0 mol dm⁻³ HCl and 50 cm³ of 1.0 mol dm⁻³ NaOH

B.  50 cm³ of 1.0 mol dm⁻³ CH₃COOH and 50 cm³ of 1.0 mol dm⁻³ NaOH

C.  50 cm³ of 1.0 mol dm⁻³ CH₃COOH and 100 cm³ of 1.0 mol dm⁻³ NaOH

D.  100 cm³ of 1.0 mol dm⁻³ CH₃COOH and 50 cm³ of 1.0 mol dm⁻³ NaOH

Which of the following statements is correct when a 1.0 M NH₄+/NH₃ buffer (pH = 9.2) is diluted to 0.5 M with water?

I.    The ability of the buffer to resist changes in pH when acids are added will decrease.

II.  The ability of the buffer to resist changes in pH when bases are added will decrease.

III. The pH of the buffer will be equal to 7.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

Determine the ratio in which 0.1 mol dm^–3 NaH₂PO₄ and 0.1 mol dm^–3 Na₂HPO₄ should be mixed to obtain a buffer with pH= 7.8.

pK_a NaH₂PO₄ = 7.20

Determine the ratio in which 0.1 mol dm^–3 NaH₂PO₄ and 0.1 mol dm^–3 Na₂HPO₄ should be mixed to obtain a buffer with pH= 7.8.

pK_a NaH₂PO₄ = 7.20

Determine the coefficients that balance the equation for the reaction of lithium with water.

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Suggest an experiment that shows that magnesium is more reactive than zinc, giving the observation that would confirm this.

Deduce what would be observed when Compound B is warmed with acidified aqueous potassium dichromate (VI).

What are the products when dilute aqueous copper (II) nitrate is electrolysed using platinum electrodes?

E^⦵ (Cu | Cu²⁺) = –0.34 V.

A scientist wants to investigate the catalytic properties of a thin layer of rhenium metal on a graphite surface.

Describe an electrochemical process to produce a layer of rhenium on graphite.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Deduce the coefficients required to complete the half-equation.

ReO₄⁻ (aq) + ____H⁺ (aq) + ____e⁻ ⇌ [Re(OH)₂]²⁺ (aq) + ____H₂O (l)        E^θ = +0.36 V

Predict, giving a reason, whether the reduction of ReO₄⁻ to [Re(OH)₂]²⁺ would oxidize Fe²⁺ to Fe³⁺ in aqueous solution. Use section 24 of the data booklet.

Which alcohol would produce a carboxylic acid when heated with acidified potassium dichromate(VI)?

A. propan-2-ol

B. butan-1-ol

C. 2-methylpropan-2-ol

D. pentan-3-ol

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

Which can show optical activity?

A.  CHBrCHCl

B.  CH₃CH₂CHBrCH₂CH₃

C.  (CH₃)₂CBrCl

D.  CH₃CH₂CH(CH₃)Br

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Which alcohol would produce a carboxylic acid when heated with acidified potassium dichromate(VI)?

A. propan-2-ol

B. butan-1-ol

C. 2-methylpropan-2-ol

D. pentan-3-ol

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

What are the products when concentrated KBr (aq) is electrolyzed?

Which is the species oxidized and the oxidizing agent in the reaction?

MnO₂ (s) + 4HCl (aq) → MnCl₂ (aq) + Cl₂ (g) + 2H₂O (l)

Consider the following electrochemical cell.

What happens to the ions in the salt bridge when a current flows?

A. Na⁺ ions flow to the zinc half-cell and SO₄²⁻ ions flow to the copper half-cell.

B. Na⁺ ions flow to the copper half-cell and SO₄²⁻ ions flow to the zinc half-cell.

C. Na⁺ and SO₄²⁻ ions flow to the copper half-cell.

D. Na⁺ and SO₄²⁻ ions flow to the zinc half-cell.

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

Which is not a requirement of the standard hydrogen electrode (SHE)?

A. V = 1 dm³

B. p(H₂) = 100 kPa

C. use of platinum as the electrode material

D. [H₃O⁺] = 1 mol dm⁻³

The cell potential for the spontaneous reaction when standard magnesium and silver half-cells are connected is +3.17 V.

Determine the cell potential at 298 K when:

     [Mg²⁺] = 0.0500 mol dm⁻³
     [Ag⁺] = 0.100 mol dm⁻³

Use sections 1 and 2 of the data booklet.

An iron nail and a copper nail are inserted into a lemon.

Explain why a potential is detected when the nails are connected through a voltmeter.

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

Consider the following table of standard electrode potentials.

Which is the strongest oxidizing agent?

A. Pb²⁺

B. Pb

C. Al³⁺

D. Al

Consider the following standard electrode potentials:

Which species will react with each other spontaneously under standard conditions?

A.  Zn²⁺(aq) + Pb (s)

B.  Pb²⁺(aq) + Br₂(l)

C.  Zn (s) + Br⁻(aq)

D.  Pb (s) + Br₂ (l)

Which class of compound is formed when a ketone is reduced?

A. primary alcohol

B. secondary alcohol

C. ether

D. carboxylic acid

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

Which statement is correct about the electrolysis of molten lead(II) bromide, PbBr₂?

A.  Br⁻ ions accept electrons at the cathode (negative electrode).

B.  Pb²⁺ ions accept electrons at the anode (positive electrode).

C.  Br⁻ ions lose electrons at the anode (positive electrode).

D.  Pb²⁺ ions lose electrons at the cathode (negative electrode).

Pure magnesium needed for making alloys can be obtained by electrolysis of molten magnesium chloride.

© International Baccalaureate Organization 2020.

Write the half-equations for the reactions occurring in this electrolysis.

How many electrons are needed when the following half-equation is balanced using the lowest possible whole numbers?

__ NO₃^– (aq) + __ H⁺(aq) + __ e^– → __ NO (g) + __ H₂O (l)

A.  1

B.  2

C.  3

D.  5

Which substance will not produce copper(II) chloride when added to dilute hydrochloric acid?

A.  $\mathrm{Cu} \left(\mathrm{s}\right)$

B.  $\mathrm{Cu}\left(\mathrm{OH}{)}_2 \right(\mathrm{s})$

C.  ${\mathrm{CuCO}}_3 \left(\mathrm{s}\right)$

D.  $\mathrm{CuO} \left(\mathrm{s}\right)$

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

An aqueous solution of silver nitrate, AgNO₃ (aq), can be electrolysed using platinum electrodes.

Formulate the half-equations for the reaction at each electrode during electrolysis.

Cathode (negative electrode):

Anode (positive electrode):

Which statements are correct for electrolysis?

I.   An exothermic reaction occurs.
II.  Oxidation occurs at the anode (positive electrode).
III. The reaction is non-spontaneous.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

What is correct for this redox reaction?

MnO₂(s) + 2$\text{I}$⁻ (aq) + 4H⁺(aq) → Mn²⁺(aq) + $\text{I}$₂(aq) + 2H₂O (l)

What are the products when concentrated aqueous copper (II) chloride is electrolysed using platinum electrodes?

What are the products of the electrolysis of molten potassium chloride, $\text{KCl\hspace{0.05em}(l)}$?

Which can be reduced to a secondary alcohol?

A.  C₂H₅COOH

B.  CH₃CH₂OCH₃

C.  (CH₃)₂CHCHO

D.  CH₃COC₂H₅

What happens to the mass of each copper electrode when aqueous copper(II) sulfate solution is electrolysed?

What would be the electrode potential, E^⦵, of the Mn²⁺(aq)|Mn (s) half-cell if Fe³⁺(aq)|Fe²⁺(aq) is used as the reference standard?

Mn²⁺ (aq) + 2e⁻ $\rightleftharpoons$ Mn (s)           E^⦵ = −1.18 V

Fe³⁺ (aq) + e⁻ $\rightleftharpoons$ Fe²⁺(aq)          E^⦵ = +0.77 V

A.  −1.95 V

B.  −0.41 V

C.  +0.41 V

D.  +1.95 V

The following occurs when metal X is added to Y sulfate solution and Z sulfate solution. (X, Y and Z represent metal elements but not their symbols.)

X (s) + YSO₄ (aq) → XSO₄ (aq) + Y (s)
X (s) + ZSO₄ (aq): no reaction

What is the order of increasing reactivity?

A.  X < Y < Z

B.  Y < X < Z

C.  Z < Y < X

D.  Z < X < Y

Write the half-equation for the reduction of hydrogen peroxide to water in acidic solution.

Deduce a balanced equation for the oxidation of Fe2+ by acidified hydrogen peroxide.

Which statement is correct when a zinc spoon is electroplated with silver?

A.  The cathode (negative electrode) is made of silver.

B.  The anode (positive electrode) is the zinc spoon.

C.  The anode (positive electrode) is made of silver.

D.  The electrolyte is zinc sulfate solution.

Deduce the half-equations for the reaction at each electrode.

In the electrolysis apparatus shown, 0.59 g of Ni is deposited on the cathode of the first cell.

What is the mass of Ag deposited on the cathode of the second cell?

A.  0.54 g

B.  0.59 g

C.  1.08 g

D.  2.16 g

Which molecule can be oxidized to a carboxylic acid by acidified potassium dichromate(VI)?

A.  Propan-1-ol

B.  Propan-2-ol

C.  2-methylpropan-2-ol

D.  Propanone

Which E^⦵ value, in V, for the reaction Mn (s) + Zn²⁺(aq) → Mn²⁺(aq) + Zn (s) can be deduced from the following equations?

Mn (s) + 2Ag⁺(aq) → Mn²⁺(aq) + 2Ag (s)     E^⦵ = 1.98 V

Zn (s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu (s)        E^⦵ = 1.10 V

Cu (s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag (s)      E^⦵ = 0.46 V

A.  0.42

B.  1.34

C.  2.62

D.  3.54

Which combination best describes what is happening to chloromethane, CH₃Cl, in the equation below?

CH₃Cl (g) + H₂(g) $\rightleftharpoons$ CH₄(g) + HCl (g)

A.  Oxidation and addition

B.  Oxidation and substitution

C.  Reduction and addition

D.  Reduction and substitution

Which aqueous solutions produce oxygen gas during electrolysis?

I.   Dilute CuCl₂(aq) with inert electrodes
II.  Dilute FeSO₄(aq) with inert electrodes
III. Dilute CuCl₂(aq) with copper electrodes

The standard electrode potentials are provided in the table:

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

The standard electrode potential of zinc can be measured using a standard hydrogen electrode (SHE).

Draw and annotate the diagram to show the complete apparatus required to measure the standard electrode potential of zinc.

What occurs during the operation of a voltaic cell based on the given reaction?

2Cr (s) + 3Fe²⁺ (aq) → 2Cr³⁺ (aq) + 3Fe (s)

Which substance is the reducing agent in the given reaction?

H⁺ (aq) + 2H₂O (l) + 2MnO₄⁻ (aq) + 5SO₂ (g) → 2Mn²⁺ (aq) + 5HSO₄⁻ (aq)

A.  H⁺

B.  H₂O

C.  MnO₄⁻

D.  SO₂

Which conditions best favour oxidation of primary alcohols directly to carboxylic acids?

A.  Excess acidified potassium dichromate (VI) and distillation

B.  Excess acidified potassium dichromate (VI) and reflux

C.  Few drops of acidified potassium dichromate (VI) and distillation

D.  Few drops of acidified potassium dichromate (VI) and reflux

The standard electrode potentials for three half-cells involving chromium are shown.

Cr³⁺ (aq) + e⁻ $\rightleftharpoons$ Cr²⁺(aq)         E^⦵  = −0.407 V

Cr³⁺ (aq) + 3e⁻ $\rightleftharpoons$ Cr (s)            E^⦵ = −0.744 V

Cr²⁺ (aq) + 2e⁻ $\rightleftharpoons$ Cr (s)            E^⦵ = −0.914 V

Which statement is correct?

A.  Cr³⁺ (aq) can oxidize Cr²⁺ (aq) but not Cr (s).

B.  Cr³⁺ (aq) can oxidize Cr (s) but not Cr²⁺ (aq).

C.  Cr³⁺ (aq) can oxidize both Cr²⁺ (aq) and Cr (s).

D.  Cr³⁺ (aq) can oxidize Cr (s) and reduce Cr²⁺ (aq).

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

Determine the coefficients that balance the equation for the reaction of lithium with water.

Determine the coefficients that balance the equation for the reaction of lithium with water.

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Deduce, giving reasons, whether the reaction of magnesium nitride with water is an acid–base reaction, a redox reaction, neither or both.

Suggest an experiment that shows that magnesium is more reactive than zinc, giving the observation that would confirm this.

Deduce what would be observed when Compound B is warmed with acidified aqueous potassium dichromate (VI).

Suggest an experiment that shows that magnesium is more reactive than zinc, giving the observation that would confirm this.

Deduce what would be observed when Compound B is warmed with acidified aqueous potassium dichromate (VI).

What are the products when dilute aqueous copper (II) nitrate is electrolysed using platinum electrodes?

E^⦵ (Cu | Cu²⁺) = –0.34 V.

A scientist wants to investigate the catalytic properties of a thin layer of rhenium metal on a graphite surface.

Describe an electrochemical process to produce a layer of rhenium on graphite.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Deduce the coefficients required to complete the half-equation.

ReO₄⁻ (aq) + ____H⁺ (aq) + ____e⁻ ⇌ [Re(OH)₂]²⁺ (aq) + ____H₂O (l)        E^θ = +0.36 V

Predict, giving a reason, whether the reduction of ReO₄⁻ to [Re(OH)₂]²⁺ would oxidize Fe²⁺ to Fe³⁺ in aqueous solution. Use section 24 of the data booklet.

A scientist wants to investigate the catalytic properties of a thin layer of rhenium metal on a graphite surface.

Describe an electrochemical process to produce a layer of rhenium on graphite.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Deduce the coefficients required to complete the half-equation.

ReO₄⁻ (aq) + ____H⁺ (aq) + ____e⁻ ⇌ [Re(OH)₂]²⁺ (aq) + ____H₂O (l)        E^θ = +0.36 V

Predict, giving a reason, whether the reduction of ReO₄⁻ to [Re(OH)₂]²⁺ would oxidize Fe²⁺ to Fe³⁺ in aqueous solution. Use section 24 of the data booklet.

Which alcohol would produce a carboxylic acid when heated with acidified potassium dichromate(VI)?

A. propan-2-ol

B. butan-1-ol

C. 2-methylpropan-2-ol

D. pentan-3-ol

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

Which can show optical activity?

A.  CHBrCHCl

B.  CH₃CH₂CHBrCH₂CH₃

C.  (CH₃)₂CBrCl

D.  CH₃CH₂CH(CH₃)Br

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Describe how the relative reactivity of rhenium, compared to silver, zinc, and copper, can be established using pieces of rhenium and solutions of these metal sulfates.

Which alcohol would produce a carboxylic acid when heated with acidified potassium dichromate(VI)?

A. propan-2-ol

B. butan-1-ol

C. 2-methylpropan-2-ol

D. pentan-3-ol

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

What are the products when concentrated KBr (aq) is electrolyzed?

Which is the species oxidized and the oxidizing agent in the reaction?

MnO₂ (s) + 4HCl (aq) → MnCl₂ (aq) + Cl₂ (g) + 2H₂O (l)

Consider the following electrochemical cell.

What happens to the ions in the salt bridge when a current flows?

A. Na⁺ ions flow to the zinc half-cell and SO₄²⁻ ions flow to the copper half-cell.

B. Na⁺ ions flow to the copper half-cell and SO₄²⁻ ions flow to the zinc half-cell.

C. Na⁺ and SO₄²⁻ ions flow to the copper half-cell.

D. Na⁺ and SO₄²⁻ ions flow to the zinc half-cell.

The following reaction occurs in a voltaic (galvanic) cell.

Mg (s) + 2Ag⁺ (aq) → Mg²⁺ (aq) + 2Ag (s)

Which reaction takes place at each electrode?

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

Which is not a requirement of the standard hydrogen electrode (SHE)?

A. V = 1 dm³

B. p(H₂) = 100 kPa

C. use of platinum as the electrode material

D. [H₃O⁺] = 1 mol dm⁻³

The cell potential for the spontaneous reaction when standard magnesium and silver half-cells are connected is +3.17 V.

Determine the cell potential at 298 K when:

     [Mg²⁺] = 0.0500 mol dm⁻³
     [Ag⁺] = 0.100 mol dm⁻³

Use sections 1 and 2 of the data booklet.

An iron nail and a copper nail are inserted into a lemon.

Explain why a potential is detected when the nails are connected through a voltmeter.

An iron nail and a copper nail are inserted into a lemon.

Explain why a potential is detected when the nails are connected through a voltmeter.

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

Consider the following table of standard electrode potentials.

Which is the strongest oxidizing agent?

A. Pb²⁺

B. Pb

C. Al³⁺

D. Al

Consider the following standard electrode potentials:

Which species will react with each other spontaneously under standard conditions?

A.  Zn²⁺(aq) + Pb (s)

B.  Pb²⁺(aq) + Br₂(l)

C.  Zn (s) + Br⁻(aq)

D.  Pb (s) + Br₂ (l)

Which class of compound is formed when a ketone is reduced?

A. primary alcohol

B. secondary alcohol

C. ether

D. carboxylic acid

Which product will be obtained at the anode (positive electrode) when molten NaCl is electrolysed?

A. Na (l)

B. Cl (g)

C. Cl₂ (g)

D. Na (s)

Which statement is correct about the electrolysis of molten lead(II) bromide, PbBr₂?

A.  Br⁻ ions accept electrons at the cathode (negative electrode).

B.  Pb²⁺ ions accept electrons at the anode (positive electrode).

C.  Br⁻ ions lose electrons at the anode (positive electrode).

D.  Pb²⁺ ions lose electrons at the cathode (negative electrode).

Pure magnesium needed for making alloys can be obtained by electrolysis of molten magnesium chloride.

© International Baccalaureate Organization 2020.

Write the half-equations for the reactions occurring in this electrolysis.

How many electrons are needed when the following half-equation is balanced using the lowest possible whole numbers?

__ NO₃^– (aq) + __ H⁺(aq) + __ e^– → __ NO (g) + __ H₂O (l)

A.  1

B.  2

C.  3

D.  5

Which substance will not produce copper(II) chloride when added to dilute hydrochloric acid?

A.  $\mathrm{Cu} \left(\mathrm{s}\right)$

B.  $\mathrm{Cu}\left(\mathrm{OH}{)}_2 \right(\mathrm{s})$

C.  ${\mathrm{CuCO}}_3 \left(\mathrm{s}\right)$

D.  $\mathrm{CuO} \left(\mathrm{s}\right)$

Describe the effect of infrared (IR) radiation on carbon dioxide molecules.

An aqueous solution of silver nitrate, AgNO₃ (aq), can be electrolysed using platinum electrodes.

Formulate the half-equations for the reaction at each electrode during electrolysis.

Cathode (negative electrode):

Anode (positive electrode):

Which statements are correct for electrolysis?

I.   An exothermic reaction occurs.
II.  Oxidation occurs at the anode (positive electrode).
III. The reaction is non-spontaneous.

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

What is correct for this redox reaction?

MnO₂(s) + 2$\text{I}$⁻ (aq) + 4H⁺(aq) → Mn²⁺(aq) + $\text{I}$₂(aq) + 2H₂O (l)

What are the products when concentrated aqueous copper (II) chloride is electrolysed using platinum electrodes?

What are the products of the electrolysis of molten potassium chloride, $\text{KCl\hspace{0.05em}(l)}$?

Which can be reduced to a secondary alcohol?

A.  C₂H₅COOH

B.  CH₃CH₂OCH₃

C.  (CH₃)₂CHCHO

D.  CH₃COC₂H₅

What happens to the mass of each copper electrode when aqueous copper(II) sulfate solution is electrolysed?

What would be the electrode potential, E^⦵, of the Mn²⁺(aq)|Mn (s) half-cell if Fe³⁺(aq)|Fe²⁺(aq) is used as the reference standard?

Mn²⁺ (aq) + 2e⁻ $\rightleftharpoons$ Mn (s)           E^⦵ = −1.18 V

Fe³⁺ (aq) + e⁻ $\rightleftharpoons$ Fe²⁺(aq)          E^⦵ = +0.77 V

A.  −1.95 V

B.  −0.41 V

C.  +0.41 V

D.  +1.95 V

The following occurs when metal X is added to Y sulfate solution and Z sulfate solution. (X, Y and Z represent metal elements but not their symbols.)

X (s) + YSO₄ (aq) → XSO₄ (aq) + Y (s)
X (s) + ZSO₄ (aq): no reaction

What is the order of increasing reactivity?

A.  X < Y < Z

B.  Y < X < Z

C.  Z < Y < X

D.  Z < X < Y

Write the half-equation for the reduction of hydrogen peroxide to water in acidic solution.

Deduce a balanced equation for the oxidation of Fe2+ by acidified hydrogen peroxide.

Write the half-equation for the reduction of hydrogen peroxide to water in acidic solution.

Deduce a balanced equation for the oxidation of Fe2+ by acidified hydrogen peroxide.

Which statement is correct when a zinc spoon is electroplated with silver?

A.  The cathode (negative electrode) is made of silver.

B.  The anode (positive electrode) is the zinc spoon.

C.  The anode (positive electrode) is made of silver.

D.  The electrolyte is zinc sulfate solution.

Deduce the half-equations for the reaction at each electrode.

Deduce the half-equations for the reaction at each electrode.

In the electrolysis apparatus shown, 0.59 g of Ni is deposited on the cathode of the first cell.

What is the mass of Ag deposited on the cathode of the second cell?

A.  0.54 g

B.  0.59 g

C.  1.08 g

D.  2.16 g

Which molecule can be oxidized to a carboxylic acid by acidified potassium dichromate(VI)?

A.  Propan-1-ol

B.  Propan-2-ol

C.  2-methylpropan-2-ol

D.  Propanone

Which E^⦵ value, in V, for the reaction Mn (s) + Zn²⁺(aq) → Mn²⁺(aq) + Zn (s) can be deduced from the following equations?

Mn (s) + 2Ag⁺(aq) → Mn²⁺(aq) + 2Ag (s)     E^⦵ = 1.98 V

Zn (s) + Cu²⁺(aq) → Zn²⁺(aq) + Cu (s)        E^⦵ = 1.10 V

Cu (s) + 2Ag⁺(aq) → Cu²⁺(aq) + 2Ag (s)      E^⦵ = 0.46 V

A.  0.42

B.  1.34

C.  2.62

D.  3.54

Which combination best describes what is happening to chloromethane, CH₃Cl, in the equation below?

CH₃Cl (g) + H₂(g) $\rightleftharpoons$ CH₄(g) + HCl (g)

A.  Oxidation and addition

B.  Oxidation and substitution

C.  Reduction and addition

D.  Reduction and substitution

Which aqueous solutions produce oxygen gas during electrolysis?

I.   Dilute CuCl₂(aq) with inert electrodes
II.  Dilute FeSO₄(aq) with inert electrodes
III. Dilute CuCl₂(aq) with copper electrodes

The standard electrode potentials are provided in the table:

A.  I and II only

B.  I and III only

C.  II and III only

D.  I, II and III

The standard electrode potential of zinc can be measured using a standard hydrogen electrode (SHE).

Draw and annotate the diagram to show the complete apparatus required to measure the standard electrode potential of zinc.

What occurs during the operation of a voltaic cell based on the given reaction?

2Cr (s) + 3Fe²⁺ (aq) → 2Cr³⁺ (aq) + 3Fe (s)

Which substance is the reducing agent in the given reaction?

H⁺ (aq) + 2H₂O (l) + 2MnO₄⁻ (aq) + 5SO₂ (g) → 2Mn²⁺ (aq) + 5HSO₄⁻ (aq)

A.  H⁺

B.  H₂O

C.  MnO₄⁻

D.  SO₂

Which conditions best favour oxidation of primary alcohols directly to carboxylic acids?

A.  Excess acidified potassium dichromate (VI) and distillation

B.  Excess acidified potassium dichromate (VI) and reflux

C.  Few drops of acidified potassium dichromate (VI) and distillation

D.  Few drops of acidified potassium dichromate (VI) and reflux

The standard electrode potentials for three half-cells involving chromium are shown.

Cr³⁺ (aq) + e⁻ $\rightleftharpoons$ Cr²⁺(aq)         E^⦵  = −0.407 V

Cr³⁺ (aq) + 3e⁻ $\rightleftharpoons$ Cr (s)            E^⦵ = −0.744 V

Cr²⁺ (aq) + 2e⁻ $\rightleftharpoons$ Cr (s)            E^⦵ = −0.914 V

Which statement is correct?

A.  Cr³⁺ (aq) can oxidize Cr²⁺ (aq) but not Cr (s).

B.  Cr³⁺ (aq) can oxidize Cr (s) but not Cr²⁺ (aq).

C.  Cr³⁺ (aq) can oxidize both Cr²⁺ (aq) and Cr (s).

D.  Cr³⁺ (aq) can oxidize Cr (s) and reduce Cr²⁺ (aq).

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

The titration of Fe(II) with MnO₄ in acid medium is a redox reaction. State the oxidised and reduced species, including their change in oxidation states.

Oxidised: ........................................................................................................................................

Reduced: ........................................................................................................................................

Which reaction involves homolytic fission?

A.  CH₄ + Cl₂

B.  CH₃Br + NaOH

C.  (CH₃)₃CBr + NaOH

D.  C₆H₆ + HNO₃ + H₂SO₄

Identify the initiation step of the reaction and its conditions.

Identify the initiation step of the reaction and its conditions.

Methane reacts with chlorine in sunlight.

CH₄ (g) + Cl₂ (g) → CH₃Cl (g) + HCl (g)

Which type of reaction occurs?

A. free-radical substitution

B. electrophilic substitution

C. nucleophilic substitution

D. electrophilic addition

Methane reacts with chlorine in sunlight.

CH₄ (g) + Cl₂ (g) → CH₃Cl (g) + HCl (g)

Which type of reaction occurs?

A. free-radical substitution

B. electrophilic substitution

C. nucleophilic substitution

D. electrophilic addition

Which is a propagation step in the free-radical substitution mechanism of ethane with chlorine?

A.  C$\text{l}$₂ → 2 •C$\text{l}$

B.  •C₂H₅ + C$\text{l}$₂ → C₂H₅C$\text{l}$ + •C$\text{l}$

C.  •C₂H₅ + •C$\text{l}$ → C₂H₅C$\text{l}$

D.  C₂H₆ + •C$\text{l}$ → C₂H₅C$\text{l}$ + •H

Which reaction involves homolytic fission?

A.  CH₄ + Cl₂

B.  CH₃Br + NaOH

C.  (CH₃)₃CBr + NaOH

D.  C₆H₆ + HNO₃ + H₂SO₄

Identify the initiation step of the reaction and its conditions.

Identify the initiation step of the reaction and its conditions.

Identify the initiation step of the reaction and its conditions.

Identify the initiation step of the reaction and its conditions.

Methane reacts with chlorine in sunlight.

CH₄ (g) + Cl₂ (g) → CH₃Cl (g) + HCl (g)

Which type of reaction occurs?

A. free-radical substitution

B. electrophilic substitution

C. nucleophilic substitution

D. electrophilic addition

Methane reacts with chlorine in sunlight.

CH₄ (g) + Cl₂ (g) → CH₃Cl (g) + HCl (g)

Which type of reaction occurs?

A. free-radical substitution

B. electrophilic substitution

C. nucleophilic substitution

D. electrophilic addition

Which is a propagation step in the free-radical substitution mechanism of ethane with chlorine?

A.  C$\text{l}$₂ → 2 •C$\text{l}$

B.  •C₂H₅ + C$\text{l}$₂ → C₂H₅C$\text{l}$ + •C$\text{l}$

C.  •C₂H₅ + •C$\text{l}$ → C₂H₅C$\text{l}$

D.  C₂H₆ + •C$\text{l}$ → C₂H₅C$\text{l}$ + •H

Explain why the reaction produces more (CH₃)₃COH than (CH₃)₂CHCH₂OH.

Explain the relative lengths of the three bonds between N and O in nitric acid.

What must be present on a nucleophile?

A. Negative charge

B. Lone pair of electrons

C. Positive charge

D. Symmetrical distribution of electrons

The benzene ring of phenylethene reacts with the nitronium ion, NO₂⁺, and the C=C double bond reacts with hydrogen bromide, HBr.

Compare and contrast these two reactions in terms of their reaction mechanisms.

Similarity: 

Difference:

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

Describe a test and the expected result to indicate the presence of carbon–carbon double bonds.

Write the equation for the reaction between but-2-ene and hydrogen bromide.

Predict, giving a reason, the major product of reaction between but-1-ene and steam.

Explain the mechanism of the reaction between 1-bromopropane, CH₃CH₂CH₂Br, and aqueous sodium hydroxide, NaOH (aq), using curly arrows to represent the movement of electron pairs.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

Write the equation for the production of the active nitrating agent from concentrated sulfuric and nitric acids.

Explain the mechanism for the nitration of benzene, using curly arrows to indicate the movement of electron pairs.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Which is a major product of the electrophilic addition of hydrogen chloride to propene?

A. ClCH₂CH=CH₂

B. CH₃CH(Cl)CH₃

C. CH₃CH₂CH₂Cl

D. CH₃CH=CHCl

State the number of coordinate covalent bonds EDTA forms with Ni²⁺.

What will be the major product in the reaction between but-1-ene and $\mathrm{Hbr}$?

A.  2-bromobut-1-ene

B.  1-bromobut-1-ene

C.  2-bromobutane

D.  1-bromobutane

In which compound is the halogen substituted the most rapidly by aqueous hydroxide ions?

A. (CH₃)₃CCl

B. (CH₃)₃CI

C. CH₃CH₂CH₂CH₂Cl

D. CH₃CH₂CH₂CH₂I

Which is a Lewis acid, but not a Brønsted-Lowry acid?

A.  ${\text{BF}}_3$

B.  ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$

C.  ${\text{NH}}_3$

D.  ${\text{Cl}}^{-}$

Which is most likely to hydrolyse via a S_N1 mechanism?

A.  CH₃CHBrCH₂CH₃

B.  (CH₃)₂CHBr

C.  (CH₃)₃CBr

D.  CH₃CH₂CH₂CH₂Br

Which is the electrophile in the nitration of benzene?

A.  ${\mathrm{HNO}}_3$

B.  ${{\mathrm{NO}}_2}^{+}$

C.  ${{\mathrm{NO}}_2}^{-}$

D.  ${{\mathrm{NH}}_4}^{+}$

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

What is the overall charge, $x$, of the chromium (III) complex?

$\left[\mathrm{Cr}\right({\mathrm{H}}_2\mathrm{O}{)}_4{\mathrm{Cl}}_2{]}^x$

A.  0

B.  1+

C.  2−

D.  3+

Which species can act both as a Lewis acid and a Lewis base?

A.  H₂O

B.  NH₄⁺

C.  Cu²⁺

D.  CH₄

Explain why the reaction produces more (CH₃)₃COH than (CH₃)₂CHCH₂OH.

Explain why the reaction produces more (CH₃)₃COH than (CH₃)₂CHCH₂OH.

Explain the relative lengths of the three bonds between N and O in nitric acid.

Explain the relative lengths of the three bonds between N and O in nitric acid.

What must be present on a nucleophile?

A. Negative charge

B. Lone pair of electrons

C. Positive charge

D. Symmetrical distribution of electrons

The benzene ring of phenylethene reacts with the nitronium ion, NO₂⁺, and the C=C double bond reacts with hydrogen bromide, HBr.

Compare and contrast these two reactions in terms of their reaction mechanisms.

Similarity: 

Difference:

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

The benzene ring of phenylethene reacts with the nitronium ion, NO₂⁺, and the C=C double bond reacts with hydrogen bromide, HBr.

Compare and contrast these two reactions in terms of their reaction mechanisms.

Similarity: 

Difference:

The minor product, C₆H₅–CH₂–CH₂Br, can be directly converted to an intermediate compound, X, which can then be directly converted to the acid C₆H₅–CH₂–COOH.

C₆H₅–CH₂–CH₂Br → X → C₆H₅–CH₂–COOH

Identify X.

Describe a test and the expected result to indicate the presence of carbon–carbon double bonds.

Write the equation for the reaction between but-2-ene and hydrogen bromide.

Predict, giving a reason, the major product of reaction between but-1-ene and steam.

Explain the mechanism of the reaction between 1-bromopropane, CH₃CH₂CH₂Br, and aqueous sodium hydroxide, NaOH (aq), using curly arrows to represent the movement of electron pairs.

Describe a test and the expected result to indicate the presence of carbon–carbon double bonds.

Write the equation for the reaction between but-2-ene and hydrogen bromide.

Predict, giving a reason, the major product of reaction between but-1-ene and steam.

Explain the mechanism of the reaction between 1-bromopropane, CH₃CH₂CH₂Br, and aqueous sodium hydroxide, NaOH (aq), using curly arrows to represent the movement of electron pairs.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

Write the equation for the production of the active nitrating agent from concentrated sulfuric and nitric acids.

Explain the mechanism for the nitration of benzene, using curly arrows to indicate the movement of electron pairs.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

Write the equation for the production of the active nitrating agent from concentrated sulfuric and nitric acids.

Explain the mechanism for the nitration of benzene, using curly arrows to indicate the movement of electron pairs.

1,4-dimethylbenzene reacts as a substituted alkane. Draw the structures of the two products of the overall reaction when one molecule of bromine reacts with one molecule of 1,4-dimethylbenzene.

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

The reaction of the hydroxide ion with carbon dioxide and with the hydrogencarbonate ion can be represented by Equations 3 and 4.

Equation (3)     OH⁻ (aq) + CO₂ (g) → HCO₃⁻ (aq)
Equation (4)     OH⁻ (aq) + HCO₃⁻ (aq) → H₂O (l) + CO₃²⁻ (aq)

Discuss how these equations show the difference between a Lewis base and a Brønsted–Lowry base.

Equation (3):

Equation (4):

Which is a major product of the electrophilic addition of hydrogen chloride to propene?

A. ClCH₂CH=CH₂

B. CH₃CH(Cl)CH₃

C. CH₃CH₂CH₂Cl

D. CH₃CH=CHCl

State the number of coordinate covalent bonds EDTA forms with Ni²⁺.

What will be the major product in the reaction between but-1-ene and $\mathrm{Hbr}$?

A.  2-bromobut-1-ene

B.  1-bromobut-1-ene

C.  2-bromobutane

D.  1-bromobutane

In which compound is the halogen substituted the most rapidly by aqueous hydroxide ions?

A. (CH₃)₃CCl

B. (CH₃)₃CI

C. CH₃CH₂CH₂CH₂Cl

D. CH₃CH₂CH₂CH₂I

Which is a Lewis acid, but not a Brønsted-Lowry acid?

A.  ${\text{BF}}_3$

B.  ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$

C.  ${\text{NH}}_3$

D.  ${\text{Cl}}^{-}$

Which is most likely to hydrolyse via a S_N1 mechanism?

A.  CH₃CHBrCH₂CH₃

B.  (CH₃)₂CHBr

C.  (CH₃)₃CBr

D.  CH₃CH₂CH₂CH₂Br

Which is the electrophile in the nitration of benzene?

A.  ${\mathrm{HNO}}_3$

B.  ${{\mathrm{NO}}_2}^{+}$

C.  ${{\mathrm{NO}}_2}^{-}$

D.  ${{\mathrm{NH}}_4}^{+}$

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A.  ${\mathrm{Cu}}^{2+}$

B.  ${{\mathrm{NH}}_4}^{+}$

C.  $\mathrm{Cu}$

D.  ${\mathrm{CH}}_3\mathrm{COOH}$

What is the overall charge, $x$, of the chromium (III) complex?

$\left[\mathrm{Cr}\right({\mathrm{H}}_2\mathrm{O}{)}_4{\mathrm{Cl}}_2{]}^x$

A.  0

B.  1+

C.  2−

D.  3+

Which species can act both as a Lewis acid and a Lewis base?

A.  H₂O

B.  NH₄⁺

C.  Cu²⁺

D.  CH₄