Practice Enthalpy, H (5.2.2) - Thermodynamics

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6 sample questions

Question 1.
What does ∆H represent in a chemical reaction?
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Think of how energy changes during a reaction.
Question 2.
Is a reaction with a negative ∆H exothermic or endothermic?
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Remember how heat moves in exothermic reactions.
3Question 3.
What is the relationship between enthalpy and heat transfer during a chemical reaction?
- Entalphy is unrelated
- Enthalpy measures heat transfer
- Both are equivalent
- None of above
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Think about how we calculate heat changes.
4Question 4.
True or False: A positive ∆H indicates an exothermic reaction.
- True
- False
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Recall the signs associated with heat flow.
Question 5.
Calculate the enthalpy change if 2 moles of H2O (l) are converted to H2O (g) at 100°C, given ∆Hvap = 40.79 kJ/mol.
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Remember the phase transition formulas for vaporization.
Question 6.
You have a reaction that involves multiple steps: A + B → C (∆H = -50 kJ), C + D → E (∆H = +20 kJ). What is the overall enthalpy change for the reaction A + B + D → E?
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Apply Hess's Law for summing the reactions.

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