Redox I (Edexcel A Level Chemistry): Exam Questions

Chlorine and iodine are in the same group in the Periodic Table.

i) Complete the electronic configuration of chlorine using the s, p, d notation. 

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 1s² ..................................................

 ii) Explain why iodine and chlorine have many similar chemical reactions. 

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Members of the same group sometimes react in different ways. 

Iodine and chlorine react differently with thiosulfate ions, S₂O₃²⁻. 

Iodine gives S₄O₆²⁻, whilst chlorine gives SO₄²⁻. 

i) Complete the table by identifying the oxidation numbers of sulfur in the three sulfur-containing ions.

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 ii) The equation for the reaction of iodine with thiosulfate ions is

 2S₂O₃²⁻ + I₂ → 2I⁻ + S₄O₆²⁻

 State, in terms of electrons, why iodine is classified as an oxidising agent in this reaction. 

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iii) Use your answer to b(i) to show that chlorine is a stronger oxidising agent than iodine. 

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iv) Chlorine reacts in aqueous solution with S₂O₃²⁻ to give SO₄²⁻.

The ionic half-equation for the reaction of chlorine is

Cl₂ + 2e⁻ → 2Cl⁻

Write the ionic half-equation for the reaction of aqueous S₂O₃²⁻ to give SO₄²⁻.

State symbols are not required. 

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 v) Use your answer to (b)(iv) and the half-equation for chlorine, to write the overall ionic equation for the reaction between chlorine and thiosulfate ions.

State symbols are not required. 

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