Practice Paper 2

The successive ionisation energies of vanadium are shown.

State the sub-levels from which each of the first four electrons are lost

Outline why there is an increase in ionisation energy from electron 3 to electron 5.

Explain why there is a large increase in the ionisation energy between electrons 5 and 6.

IE1	IE2	IE3	IE4	IE5	IE6
578	1816	2744	11576	14829	18375

 

Explain the large increase in ionisation energy from IE₃ to IE₄

When chromium(III) sulfate dissolves in water, a green solution containing the [Cr(H₂O)₆]³⁺ ion forms.

Vanadium(V) oxide is the catalyst used in the Contact process as shown by the reactions:

SO₂ (g) + V₂O₅ (s) → SO₃ (g) + V₂O₄ (s)

V₂O₄ (s) + ½O₂ (g) → V₂O₅ (s)

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Excess ammonia is added to a solution of Cu²⁺ ions resulting in the substitution of 4 ligands.

Using section 15 of the data booklet, explain why this reaction results in a shift in the wavelength of light absorbed by the Cu²⁺ complex.

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Ibuprofen is a common non-steroidal anti-inflammatory drug (NSAID). It contains a benzene ring and a carboxylic acid at the end of one of the branches.

Deduce the number of:

 

Sigma (σ) bonds in ibuprofen

Pi (π) electrons in ibuprofen

The ibuprofen molecule contains both sp³ and sp² hybridised orbitals.

 

Identify how many sp³ hybrid orbitals are present.

Identify how many sp² hybrid orbitals are present.

Explain why the benzene ring is a regular, planar hexagon.

State the formula for calculating the standard enthalpy change of reaction, ΔH_r, using bond energies.

Use section 11 of the data booklet to calculate the enthalpy change, in kJ mol^-1, for the following reaction.    

State whether the energy change for the reaction in part (b) is endothermic or exothermic.

Using section 11 of the data booklet, calculate the enthalpy change of reaction, ΔH_r, in kJ mol^-1 for the following reaction.

A student measured the energy change when 1.35 g of zinc was added to 50 cm³ of 0.5 mol dm^-3 copper sulfate, CuSO₄ (aq), solution. The initial temperature of 21 ^oC was recorded before the addition of the zinc and a temperature reading was taken every 30 seconds.

Use the graph to determine the overall temperature change for the reaction

Calculate the enthalpy change for the reaction in kJ mol^-1.

Calculate the percentage error between your value for the enthalpy change of reaction and the literature value of -217 kJ mol^-1. Give your answer to two significant figures. 

Explain why your calculated value for the enthalpy change of reaction is different from the literature value of -271 kJ mol^-1. 

Define the term nucleophile. 

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Explain why the hydroxide ion, OH^- , is a stronger nucleophile than water. 

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State the two ways a nucleophilic substitution reaction can occur. 

State the the name of the mechanism occurring in the image below which will form ethanol in one step. 

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Ethane-1,2-diol, C₂H₆O₂, can be distinguished from ethanedioic acid,C₂H₂O₄, by a number of analytic techniques including MS, IR and NMR 

The MS of these molecules is shown below. 

Which spectrum belongs to each molecule? Justify your answer.

 

Spectrum A

Spectrum B

The IR spectra of ethane-1,2-diol, C₂H₆O₂, and ethanedioic acid dihydrate,C₂H₂O₄.2H₂O, are shown in spectrum C and D. Use Section 26 of the Data Booklet to answer this question.

Spectrum CSpectrum D

Which spectrum belongs to each molecule? Justify your answer.

The ¹H NMR spectrum of ethane-1,2-diol is shown in spectrum E. Explain the significance of the spectrum.

Spectrum E

Suggest two modifications to the procedure which would make the result more reliable.