Form 4 Chemistry Exercise
Cut the following questions separately and paste them onto
your chemistry exercise books. Answer the questions
Repeat the “cut and paste action” for each question.
Chapter 16 Ex1
1. Which of the following are redox reactions? Explain in terms of
ANY change in oxidation numbers.
(a) SO3(g) + H 2O(l) → H2SO4(aq)
(b) Cu(s) + 4HNO 3(aq) → Cu(NO3) 2(aq) + 2NO 2(g) + 2H2O(l)
(c) Na 2CO 3(aq) + HCl(aq) → NaCl(aq) + NaHCO3(aq)
(d) 2KClO3(s) → 2KCl(s) + 3O2(g)
2. An experiment was performed by using the set-up shown in the
figure below:
(a) Write a half-equation for the change occurring at electrode
(i) A
(ii) B.
(b) Write an ionic equation for the overall reaction which takes place.
(c) In what direction do electrons flow in the external circuit?
(d) If sodium sulphite solution and iron(III) chloride solution are
mixed directly, do you expect the same overall reaction as in (b)?
Is electricity generated in this case?
3. Calculate the oxidation number of the underlined elements in
each of the following:
(a) MgSO4
(b) KMnO4
(c) NaH
(d) CrCl3
(e) HSO4-