Enthalpy Concepts Worksheet
This worksheet covers fundamental concepts of enthalpy, including exothermic and endothermic reactions, enthalpy changes, and Hess's Law, suitable for Grade 11 Chemistry students.
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Enthalpy Concepts Worksheet
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Read each question carefully and provide your best answer. Show all your work for calculations.
1. Which of the following best describes an exothermic reaction?
A reaction that absorbs heat from the surroundings.
A reaction that releases heat to the surroundings.
A reaction with no change in heat.
A reaction that only occurs at high temperatures.
2. What is the standard enthalpy of formation (ΔH°f) for a pure element in its most stable form?
Positive
Negative
Zero
Undefined
1. Enthalpy is a state function, meaning its value depends only on the initial and final states of the system.
True
False
2. An endothermic reaction feels cold to the touch because it releases heat to the surroundings.
True
False
1. The change in enthalpy for a reaction is represented by the symbol .
2. 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.
1. Explain the difference between enthalpy and internal energy.
2. Describe how calorimetry is used to measure enthalpy changes.
3. Given the following reactions:
C(s) + O₂(g) → CO₂(g) ΔH = -393.5 kJ/mol
H₂(g) + ½O₂(g) → H₂O(l) ΔH = -285.8 kJ/mol
C₂H₂(g) + ⁵/₂O₂(g) → 2CO₂(g) + H₂O(l) ΔH = -1300 kJ/mol
Calculate the enthalpy change for the reaction: 2C(s) + H₂(g) → C₂H₂(g)