Enthalpy

Practice Questions

GRE Subject Test: Chemistry › Enthalpy

Questions

Which is not characteristic of an endothermic reaction?

$H_{2}+\frac{1}{2}O_{2}\rightarrow H_{2} O\ \ \Delta H_{f}^{0} = - 286 kJ$

$C + O_{2}\rightarrow CO_{2} \ \ \Delta H_{f}^{0} = - 394 kJ$

$8C + 9H_{2}\rightarrow C_{8} H_{18}\ \ \Delta H_{f}^{0} = -269 kJ$

Given the enthalpies of formation, what is the enthalpy of combustion of octane in the reaction:

$2C_{8}H_{18}+25O_{2}\rightarrow 16CO_{2} +18H_{2}O$

Propane gas combusts according the following chemical equation:

$C_{3}H_{8} + 5O_{2} \rightarrow 3CO_{2} + 4H_{2}O$

Given the following standard enthalpy values, what is the enthalpy of the reaction for the combustion of one mole of propane?

$\Delta H_{C_{3}H_{8}} = -103.8\frac{kJ}{mol}$

$\Delta H_{O_{2}} = 0\frac{kJ}{mol}$

$\Delta H_{CO_{2}} = -393.5\frac{kJ}{mol}$

$\Delta H_{H_{2}O} = -241.8\frac{kJ}{mol}$