Marking criteria for option 3:
- (1) Substitution of 36,5 g∙mol-1 n = m/M.
- (2) Initial concentration of reactants: c(HCℓ) = 1,0 & c(O2) = 0,55 mol∙dm-3.
- (3) Change: c(HCℓ) = 0,75 mol∙dm-3 (initial – equilibrium)
- (4) Using ratio: 4: 1: 2: 2.
- (5) Equilibrium: c(H2O) = c(Cℓ2) = 0,3625 mol∙dm-3 (initial+change) and c(O2) = 0,3625 mol∙dm-3 (initial – change).
- (6) Correct Kc expression (formulae in square brackets).
- (7) Substitution of reactant concentrations.
- (8) Substitution of product concentrations.
- (9) Final answer: 13,97.
- Range: 13,966 to 18,72.
Or
Option 2
(1)
(2)
(3)
(4)
(5)
(6 + 7 + 8 + 9)
Or
Option 3
(1)
HCl | O2 | H2O | Cl2 | |
Initial concentration (mol∙dm-3) | 1,0 (2) | 0,55 | 0 | 0 |
Change in concentration (mol∙dm-3) | 0,75 (3) | 0,1875 | 0,375 | 0,375 |
Equilibrium concentration (mol∙dm-3) | 0,25 | 0,3625 | 0,375 | 0,375 |
Divide by 0,2. (5)
Ratio. (4)
(6 + 7 + 8 + 9)