Enthalpy of Formation Worksheet
This worksheet covers the fundamental concepts of enthalpy of formation, including definitions, calculations, and Hess's Law.
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Enthalpy of Formation Worksheet
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Read each question carefully and answer to the best of your ability. Show all work for calculations.
1. What is the standard enthalpy of formation (ΔH°f) for an element in its most stable form?
Positive
Negative
Zero
Depends on the element
2. Which of the following statements is true regarding an exothermic reaction?
ΔH is positive
Heat is absorbed
ΔH is negative
Temperature decreases
3. The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states is called the standard enthalpy of .
4. Hess's Law states that if a reaction can be expressed as a series of steps, then the enthalpy change for the overall reaction is the of the enthalpy changes for the individual steps.
5. The standard enthalpy of formation of H₂(g) is 0 kJ/mol.
True
False
6. An endothermic reaction feels cold to the touch because it releases heat to the surroundings.
True
False
7. Define standard enthalpy of formation. Why is it useful in chemistry?
8. Given the following standard enthalpies of formation:
ΔH°f [CO₂(g)] = -393.5 kJ/mol
ΔH°f [H₂O(l)] = -285.8 kJ/mol
ΔH°f [CH₄(g)] = -74.8 kJ/mol
Calculate the enthalpy change for the combustion of methane (CH₄):
CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)