Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

8. Thermochemistry

Constant-Pressure Calorimetry

General Chemistry

8. Thermochemistry

Constant-Pressure Calorimetry

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Multiple Choice

You are experimentally determining the change in enthalpy when dissolving an ionic compound in water using a coffee-cup calorimeter. When you dissolve 38.28 g of the ionic compound (molar mass = 102 g/mol) in 369 g of water in a coffee-cup calorimeter, the temperature of the solution changes from 25.0°C to 28.5°C. Given that the specific heat capacity of water is 4.18 J/g°C, what is the change in enthalpy (ΔH) for the dissolution process?

5.2 kJ/mol

15.6 kJ/mol

-15.6 kJ/mol

-5.2 kJ/mol

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Verified step by step guidance

Calculate the number of moles of the ionic compound using its mass and molar mass. Use the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Determine the heat absorbed or released by the water using the formula: \( q = m \cdot c \cdot \Delta T \), where \( m \) is the mass of water, \( c \) is the specific heat capacity, and \( \Delta T \) is the change in temperature.

Calculate the change in temperature (\( \Delta T \)) of the water by subtracting the initial temperature from the final temperature.

Since the calorimeter is assumed to be perfectly insulated, the heat change of the solution is equal to the heat change of the water but with the opposite sign. Therefore, \( q_{\text{solution}} = -q_{\text{water}} \).

Calculate the change in enthalpy (\( \Delta H \)) per mole of the ionic compound by dividing the heat change of the solution by the number of moles of the ionic compound: \( \Delta H = \frac{q_{\text{solution}}}{\text{moles}} \).