Question

Select all the correct answers.

Based on the enthalpy changes given for the reactions, which reactions are endothermic?

2H2O → 2H2 + O2, ΔH = 484 kJ
C + O2 → CO2, ΔH = -394 kJ
H2 + Br2 → 2HBr, ΔH = -73 kJ
2NH3 → N2 + 3H2, ΔH = 92 kJ

Answer 1

$\\ \sf\ast\Rrightarrow 2H_2O\longrightarrow 2H_2+O_2,\Delta H=484J$

$\\ \sf\ast\Rrightarrow 2NH_3\longrightarrow N_2+3H_2,\Delta H=92J$

• Note it down

$\\ \sf\ast\Rrightarrow \Delta H=+ve(Endothermic)$

$\\ \sf\ast\Rrightarrow \Delta H=-ve(Exothermic)$