General Chemistry Practice Test #4 – Step-by-Step Study Guidance

Using Hess's Law and the following reactions, calculate $\Delta H$ for the reaction: $2\ \mathrm{C}(s) + 2\ \mathrm{H}_2\mathrm{O}(g) \rightarrow \mathrm{CH}_4(g) + \mathrm{CO}_2(g)$ Given: $\mathrm{CO}(g) + \mathrm{H}_2(g) \rightarrow \mathrm{C}(s) + \mathrm{H}_2\mathrm{O}(g)\ \ \Delta H = -131\ \mathrm{kJ}$ $\mathrm{CO}(g) + \mathrm{H}_2\mathrm{O}(g) \rightarrow \mathrm{CO}_2(g) + \mathrm{H}_2(g)\ \ \Delta H = -41\ \mathrm{kJ}$ $\mathrm{CO}(g) + 3\ \mathrm{H}_2(g) \rightarrow \mathrm{CH}_4(g) + \mathrm{H}_2\mathrm{O}(g)\ \ \Delta H = -206\ \mathrm{kJ}$

Given the following standard enthalpies of formation, calculate $\Delta H$ for the reaction: $3\ \mathrm{Fe}_2\mathrm{O}_3(s) + \mathrm{CO}(g) \rightarrow 2\ \mathrm{Fe}_3\mathrm{O}_4(s) + \mathrm{CO}_2(g)$ Heats of Formation: $\mathrm{Fe}_2\mathrm{O}_3(s) = -824.2\ \mathrm{kJ/mol}$ $\mathrm{Fe}_3\mathrm{O}_4(s) = -1118.4\ \mathrm{kJ/mol}$ $\mathrm{CO}(g) = -110.5\ \mathrm{kJ/mol}$ $\mathrm{CO}_2(g) = -393.5\ \mathrm{kJ/mol}$

The combustion of ethane is represented by: $2\ \mathrm{C}_2\mathrm{H}_6(g) + 7\ \mathrm{O}_2(g) \rightarrow 4\ \mathrm{CO}_2(g) + 6\ \mathrm{H}_2\mathrm{O}(l)\ \ \Delta H = -3120\ \mathrm{kJ}$ How much energy is released when $30.00\ \mathrm{g}$ of ethane is combusted? (Molar mass $\mathrm{C}_2\mathrm{H}_6 = 30.08\ \mathrm{g/mol}$)