Skip to content

Course home

Sign up

5.3 Equilibria

EasyMediumHard
12345678910111213141516171819202122232425
Question 21
H

Iron(III) ions react with thiocyanate ions to form a dark red ion.

Fe3+(aq)+SCN−(aq)⇌FeSCN2+(aq) \mathrm{Fe^{3+}(aq) + SCN^{-}(aq) \rightleftharpoons FeSCN^{2+}(aq)} Fe3+(aq)+SCN−(aq)⇌FeSCN2+(aq)

Solutions containing only Fe3+\mathrm{Fe^{3+}}Fe3+ ions or only SCN−\mathrm{SCN^{-}}SCN− ions are very pale. The forward reaction is exothermic.

Which change makes the equilibrium mixture paler?

[1]
A

Adding more iron(III) ions

B

Adding more thiocyanate ions

C

Adding sodium hydroxide, which reacts with iron(III) ions to form a precipitate

D

Cooling the mixture in an ice bath

Markscheme

5.3 Equilibria Questions

  1. GCSE
  2. /Chemistry
  3. /5.3 Equilibria

47 exam-style questions on OCR GCSE Chemistry 5.3 Equilibria, covering 5.3.1 Reversible reactions and dynamic equilibrium and 5.3.2 Changing the position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.

Question bank