Chemistry · May / June 2017 · Paper 12 · Question 15

The formation of liquid water from hydrogen and oxygen may occur in three stages. 1 2H2(g) + O2(g) → 4H(g) + 2O(g) 2 4H(g) + 2O(g) → 2H2O(g) 3 2H2O(g) → 2H2O(l) Which stages would be exothermic?

1. A1, 2 and 3
2. B1 and 2 only
3. C2 and 3 only
4. D2 only

As printed in the paper