A-LevelChemistryElectrochemistry9701/12 · Oct/Nov 2013 · Q161 Mark

Solid potassium halides react with concentrated sulfuric acid, according to the following equations. reaction 1 2KCl + H2SO4 → K2SO4 + 2HCl reaction 2 2KBr + 2H2SO4 → K2SO4 + SO2 + Br2 + 2H2O reaction 3 8KI + 5H2SO4 → 4K2SO4 + H2S + 4I2 + 4H2O What is the largest change in the oxidation number of sulfur in each of these reactions?

A0 (reaction 1), 0 (reaction 2), 4 (reaction 3)

B0 (reaction 1), 2 (reaction 2), 4 (reaction 3)

C0 (reaction 1), 2 (reaction 2), 8 (reaction 3)

D0 (reaction 1), 4 (reaction 2), 8 (reaction 3)

✓ Correct answer

C: 0 (reaction 1), 2 (reaction 2), 8 (reaction 3)

Oracle Prep sorts past-paper questions by topic, so you can drill Electrochemistry and see which topics are most likely to come up next.

Topic: Electrochemistry, A-Level Chemistry (syllabus 9701). Multiple choice, 1 mark.
Source: A-Level Chemistry, Oct/Nov 2013 Paper 1 Variant 2, question 16.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content