Oxidation & reduction questions (2)

Assignment: Questions on Topic 9.1 : Oxidation & reduction questions (2)

This page of questions can be marked as direct student access either for assigning as a test or for students to work on in their own time. If you do not wish to use student access, links to downloadable versions of the questions and, separately the worked answers, can be found at Printable versions of written tasks.

 

Consider the following four reactions:

Mg(s) + Fe2+(aq) → Mg2+(aq) + Fe(s)
Fe(s) + Ni2+(aq) → Fe2+(aq) + Ni(s)
Zn(s) + Fe2+(aq) → Zn2+(aq) + Fe(s)
Mg(s) + Zn2+(aq) → Mg2+(aq) + Zn(s)

i. Place the metals in order of their decreasing reactivity (most reactive first).

2 lines
Show model answer

ii. Identify the strongest oxidizing agent among the species above.

2 lines
Show model answer

iii. Identify the strongest reducing agent among the species above.

2 lines
Show model answer

 

 

A ‘tin’ can is actually a steel can coated with tin. When the can is dented and exposed to air and water it rusts much quicker than if the steel had been coated with zinc. Explain this fact and suggest why cans for storing food are coated with tin rather than zinc to protect them from rusting.

5 lines
Show model answer

 

 

Consider the following three reactions:

Cl2(aq) + 2Br−(aq) → 2Cl−(aq) + Br2(aq)
Cl2(aq) + 2I−(aq) → 2Cl−(aq) + I2(aq)
Br2(aq) + 2I−(aq) → 2Br−(aq) + I2(aq)

i. Identify the species that is the strongest oxidizing agent.

1 line
Show model answer


ii. Identify the species that is the strongest reducing agent.

1 line
Show model answer

iii. Explain how bromine is behaving in the first and third reactions.

3 lines
Show model answer

iv. Describe what will be observed when a yellow-brown aqueous solution of iodine is added to an aqueous solution of sodium chloride.

3 lines
Show model answer

 

 

An excess of manganese(II) sulfate in alkaline solution was added to 250 cm3 of a sample of water taken from a local lake. The oxygen in the water reacts with manganese(II) sulfate according to the equation:

2Mn2+(aq) + 4OH−(aq) + O2(g) → 2MnO2(s) + 2H2O(l)

The solution was then acidified and excess potassium iodide was then added which released iodine according to the equation:

MnO2(s) + 2I−(aq) + 4H+(aq) → Mn2+(aq) + I2(aq) + 2H2O(l)

The iodine formed was then titrated with 1.00 x 10−2 mol dm−3 sodium thiosulfate solution using starch as an indicator:

I2(aq) + 2S2O32−(aq) → S4O62−(aq) + 2I−(aq)
 

The volume of thiosulfate solution required to react completely with the iodine was 20.0 cm3.

i.  Calculate the solubility of the oxygen in the lake water in mol dm−3.

10 lines
Show model answer

ii. Calculate the solubility of the oxygen in the lake water in mg dm−3, which is the same as ppm.

2 lines
Show model answer

 

 

All materials on this website are for the exclusive use of teachers and students at subscribing schools for the period of their subscription. Any unauthorised copying or posting of materials on other websites is an infringement of our copyright and could result in your account being blocked and legal action being taken against you.