Chemistry 5070 · O Level · Exothermic and endothermic reactions

Exothermic and endothermic reactions — practice question

The production of liquid water from hydrogen and oxygen can take place in three steps. $1\quad 2\text{H}_2(\text{g}) + \text{O}_2(\text{g}) \rightarrow 4\text{H}(\text{g}) + 2\text{O}(\text{g})$ $2\quad 4\text{H}(\text{g}) + 2\text{O}(\text{g}) \rightarrow 2\text{H}_2\text{O}(\text{g})$ $3\quad 2\text{H}_2\text{O}(\text{g}) \rightarrow 2\text{H}_2\text{O}(\ell)$ Which stage or stages would be exothermic?

  • A1, 2 and 3
  • B1 and 2 only
  • C2 and 3 only
  • D2 only

Worked solution & mark scheme

This 1-mark question has a full step-by-step worked solution and mark scheme.

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI