Practice Statement Of Hess’s Law (2.2.1) - Unit 5: Energetics and Thermochemistry

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6 sample questions

Question 1.
What does Hess's Law state?
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Think about the enthalpy being a state function.
Question 2.
What is a state function?
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Does it depend on how you got there?
3Question 3.
What does Hess's Law indicate about total enthalpy change?
- Is path-dependent.
- Is path-independent.
- Depends only on reactants.
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Consider if the steps matter.
4Question 4.
True or False: Hess's Law can be utilized to calculate the enthalpy changes from known reactions.
- True
- False
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Think about combining reactions.
Question 5.
Calculate the ΔH for the reaction: 2 H₂(g) + O₂(g) → 2 H₂O(l) using Hess's Law if you know the standard enthalpy of formation for H₂O is -285.8 kJ/mol.
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Remember to account for each mole of product formed.
Question 6.
If the formation enthalpy of CO(g) is -110.5 kJ/mol and that for O₂ is zero, what would be the total ΔH for the reaction: C(s) + O₂(g) → CO(g) using Hess's Law?
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Use the fact that elemental states have zero formation enthalpy.

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