Question

Classify each reaction as endothermic or exothermic.

H2 + Br2 → 2HBr, ΔH = -73 kJ
2NH3 → N2 + 3H2, ΔH = 92 kJ
CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ
2HCl → H2 + Cl2, ΔH = 184 kJ

Answer 1

H2 + Br2 → 2HBr, ΔH = -73 kJ ⇔ Exothermic

CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ ⇔ Exothermic

2NH3 → N2 + 3H2, ΔH = 92 kJ ⇔ Endothermic

2HCl → H2 + Cl2, ΔH = 184 kJ ⇔ Endothermic

Answer 2

The correct answers are

Exothermic:

H2 + Br2 → 2HBr, ΔH = -73 kJ

CH4 + 2O2 → CO2 + 2H2O, ΔH = -890 kJ

Endothermic

2NH3 → N2 + 3H2, ΔH = 92 kJ

2HCl → H2 + Cl2, ΔH = 184 kJ

:)