Practice Standard Enthalpy Of Formation (δh_f°) (1.2.2.1) - Unit 5: Energetics and Thermochemistry

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6 sample questions

Question 1.
What is the standard enthalpy of formation for oxygen gas (O₂)?
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Think about elements in their most stable form.
Question 2.
Is the reaction of hydrogen and oxygen to form water exothermic or endothermic?
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Recall the sign of ΔH_f° for water.
3Question 3.
What does ΔH_f° represent?
- A measure of temperature change
- Enthalpy change for formation of a compound
- Density of a gas at standard pressure
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Think about what formation means in chemistry.
4Question 4.
Which reaction has a negative ΔH_f° value?
- True
- False
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Consider standard formation reactions that release heat.
Question 5.
Using provided ΔH_f° values, calculate the enthalpy change for forming ammonia (NH₃) from nitrogen and hydrogen.
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Consult the standard enthalpy chart for reference.
Question 6.
Given the ΔH_f° values of H₂O(l) and CO₂(g), determine the ΔH for photosynthesis.
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Reverse reactions appropriately to apply Hess's Law.

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