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The standard molar heat of formation is also refered to as the standard enthalpy of formation. The chart below shows standard molar heats of formation, i.e. a list of some synthesis reactions and their corresponding standard enthalpy variation. These enthalpy variations are measured under standard conditions at SATP (Standard Ambient Temperature and Pressure), i.e. at |25\ °\text{C}| and at |101.3\ \text{kPa}.|
| Synthesis Reactions | Standard Molar Heats of Formation |
|---|---|
| |\text{H}_{2(g)} + \dfrac{1}{2}\ \text{O}_{2(g)} \rightarrow \text{H}_2\text{O}_{\text{(g)}}| | |\Delta H^\circ_f = -242.2\ \text {kJ}| |
| |\text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{H}_2\text{O}_{\text{(l)}}| | |\Delta H^\circ_f = -286.2\ \text {kJ}| |
| |\text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{H}_2\text{O}_{\text{(s)}}| | |\Delta H^\circ_f = -292.2\ \text {kJ}| |
| |\text{C}_{\text{(s)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{CO}_{\text{(g)}}| | |\Delta H^\circ_f = -110.7\ \text {kJ}| |
| |\text{C}_{\text{(s)}} + \text{O}_{2\text{(g)}} \rightarrow \text{CO}_{2\text{(g)}}| | |\Delta H^\circ_f = -394.1\ \text {kJ}| |
| |\text{C}_{\text{(s)}} + 2\ \text{H}_{2\text{(g)}} \rightarrow \text{CH}_{4\text{(g)}}| | |\Delta H^\circ_f = -74.9\ \text {kJ}| |
| |2\ \text{C}_{\text{(s)}} + 2\ \text{H}_{2(g)} \rightarrow \text{C}_2\text{H}_{4\text{(g)}}| | |\Delta H^\circ_f = 52.3\ \text {kJ}| |
| |2\ \text{C}_{\text{(s)}} + 3\ \text{H}_{2\text{(g)}} \rightarrow \text{C}_2\text{H}_{6\text{(g)}}| | |\Delta H^\circ_f = -84.8\ \text {kJ}| |
| |3\ \text{C}_{\text{(s)}} + 4\ \text{H}_{2\text{(g)}} \rightarrow \text{C}_3\text{H}_{8\text{(g)}}| | |\Delta H^\circ_f = -103.8\ \text {kJ}| |
| |\text{C}_{\text{(s)}} + 2\ \text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{CH}_3\text{OH}_{\text{(l)}}| | |\Delta H^\circ_f = -238.8\ \text {kJ}| |
| |2\ \text{C}_{\text{(s)}} + \text{H}_{2\text{(g)}} \rightarrow \text{C}_2\text{H}_{2\text{(g)}}| | |\Delta H^\circ_f = 226.6\ \text {kJ}| |
| |\text{C}_{\text{(s)}} + 2\ \text{S}_{\text{(s)}} \rightarrow \text{CS}_{2\text{(l)}}| | |\Delta H^\circ_f = 89.8\ \text {kJ}| |
| |\text{S}_{(s)} + \text{O}_{2\text{(g)}} \rightarrow \text{SO}_{2\text{(g)}}| | |\Delta H^\circ_f = -297.3\ \text {kJ}| |
| |\text{S}_{\text{(s)}} + \dfrac{3}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{SO}_{3\text{(g)}}| | |\Delta H^\circ_f = -396.3\ \text {kJ}| |
| |\text{S}_{\text{(s)}} + \text{H}_{2\text{(g)}} \rightarrow \text{H}_2\text{S}_{\text{(g)}}| | |\Delta H^\circ_f = -20.2\ \text {kJ}| |
| |\text{S}_{\text{(s)}} + \text{H}_{2\text{(g)}} + 2\ \text{O}_{2\text{(g)}} \rightarrow \text{H}_2\text{SO}_{4\text{(l)}}| | |\Delta H^\circ_f = -811.4\ \text {kJ}| |
| |2\ \text{Fe}_{\text{(s)}} + \dfrac{3}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{Fe}_2\text{O}_{3\text{(s)}}| | |\Delta H^\circ_f = -825.4\ \text {kJ}| |
| |3\ \text{Fe}_{\text{(s)}} + 2\ \text{O}_{2\text{(g)}} \rightarrow \text{Fe}_3\text{O}_{4\text{(s)}}| | |\Delta H^\circ_f = -1\,120\ \text {kJ}| |
| |\text{N}_{2\text{(g)}} + \dfrac{3}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{N}_2\text{O}_{3\text{(g)}}| | |\Delta H^\circ_f = 83.8\ \text {kJ}| |
| |\text{N}_{2\text{(g)}} + 2\ \text{O}_{2\text{(g)}} \rightarrow \text{N}_2\text{O}_{4\text{(g)}}| | |\Delta H^\circ_f = 9.2\ \text {kJ}| |
| |\dfrac{3}{2}\ \text{N}_{2\text{(g)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{NO}_{\text{(g)}}| | |\Delta H^\circ_f = 90.5\ \text {kJ}| |
| |\dfrac{1}{2}\ \text{N}_{2\text{(g)}} + \text{O}_{2\text{(g)}} \rightarrow \text{NO}_{2\text{(g)}}| | |\Delta H^\circ_f = 33.9\ \text {kJ}| |
| |\dfrac{1}{2}\ \text{N}_{2\text{(g)}} + \dfrac{1}{2}\ \text{H}_{2\text{(g)}} \rightarrow \text{NH}_{3\text{(g)}}| | |\Delta H^\circ_f = -46.2\ \text {kJ}| |
| |\dfrac{1}{2}\ \text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{I}_{2\text{(s)}} \rightarrow \text{HI}_{\text{(g)}}| | |\Delta H^\circ_f = 25.9\ \text {kJ}| |
| |\dfrac{1}{2}\ \text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{I}_{2\text{(g)}} \rightarrow \text{HI}_{\text{(g)}}| | |\Delta H^\circ_f = 5\ \text {kJ}| |
| |\dfrac{1}{2}\ \text{H}_{2\text{(g)}} + \dfrac{1}{2}\ \text{Cl}_{2\text{(g)}} \rightarrow \text{HCl}_{\text{(g)}}| | |\Delta H^\circ_f = -92\ \text {kJ}| |
| |\text{Mg}_{\text{(s)}} + \dfrac{1}{2}\ \text{O}_{2\text{(g)}} \rightarrow \text{MgO}_{\text{(s)}}| | |\Delta H^\circ_f = -602\ \text {kJ}| |