Enthalpy Stoichiometry Worksheet
Grade 11 Chemistry worksheet on enthalpy stoichiometry, focusing on calculating heat changes in chemical reactions.
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Topics
Enthalpy Stoichiometry
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Read each question carefully and provide clear, concise answers. Show all your work for calculations.
1. Which of the following statements correctly describes an exothermic reaction?
Heat is absorbed from the surroundings.
The enthalpy change (ΔH) is positive.
Heat is released to the surroundings.
The products have higher energy than the reactants.
2. In an endothermic reaction, the system energy from its surroundings.
3. Hess's Law states that the total enthalpy change for a reaction is independent of the taken.
4. Consider the combustion of propane: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l) ΔH = -2220 kJ/mol. Calculate the heat released when 5.0 moles of propane are completely burned.
5. If 25.0 grams of water are formed in the reaction above, how much heat was released? (Molar mass of H₂O = 18.02 g/mol)
6. The standard enthalpy of formation for an element in its standard state is always zero.
True
False
7. Given the following reactions:
C(s) + O₂(g) → CO₂(g) ΔH₁ = -393.5 kJ
H₂(g) + ½O₂(g) → H₂O(l) ΔH₂ = -285.8 kJ
2C(s) + H₂(g) → C₂H₂(g) ΔH₃ = +226.7 kJ
Calculate ΔH for the reaction: C₂H₂(g) + ⁵/₂O₂(g) → 2CO₂(g) + H₂O(l)