The Periodic Table Structured Questions | Cambridge IGCSE Chemistry

Chemistry 0620 · Question 1[13 marks]

Halogens undergo displacement reactions based on their position down Group VII.

(a)

Chlorine gas is prepared in the laboratory by reacting manganese(IV) oxide with concentrated hydrochloric acid:

$\ce{MnO2(s)}$ + 4HCl(aq) → $\ce{MnCl2(aq)}$ + 2 $\ce{H2O(l)}$ + $\ce{Cl2(g)}$

[4]

(i)

Identify the oxidizing agent in this reaction, giving a reason in terms of oxidation state change.

[2]

(ii)

Describe a chemical test for chlorine gas and state the positive result.

[2]

(b)

Chlorine gas is bubbled into an aqueous solution containing potassium iodide.

[4]

(i)

Describe the color change observed in the solution.

[1]

(ii)

Write the ionic equation, including state symbols, for this reaction.

[2]

(iii)

If starch solution is added to the product mixture, state the observation.

[1]

(c)

Fluorine ( $\ce{F2}$ ) is the most reactive halogen, while iodine ( $\ce{I2}$ ) is much less reactive.

[5]

(i)

Explain why fluorine is significantly more reactive than iodine in terms of nuclear charge, atomic radius, and electron shielding.

[3]

(ii)

Write a balanced chemical equation for the reaction between fluorine gas and cold water, forming hydrofluoric acid (HF) and oxygen gas ( $\ce{O2}$ ).

[2]