6. Thermochemistry

Enthalpy Of Formation — Quiz

Test your understanding of enthalpy of formation with 5 practice questions.

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Practice Questions

Question 1

What is the standard enthalpy of formation of a substance?

Question 2

What is the standard enthalpy of formation of an element in its standard state?

Question 3

Which equation represents a standard enthalpy of formation reaction for water, $\mathrm{H_2O(l)}$?

Question 4

Use Hess's law to find $\Delta H^\circ_{\text{rxn}}$ for $\mathrm{CH_4(g) + 2O_2(g) \rightarrow CO_2(g) + 2H_2O(l)}$ if $\Delta H_f^\circ$ values are $\mathrm{CH_4(g)} = -74.8\ \mathrm{kJ/mol}$, $\mathrm{CO_2(g)} = -393.5\ \mathrm{kJ/mol}$, and $\mathrm{H_2O(l)} = -285.8\ \mathrm{kJ/mol}$, with $\mathrm{O_2(g)} = 0$.

Question 5

Which substance has a standard enthalpy of formation of $0$ because it is already an element in its standard state?