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-Volume Calorimetry

General Chemistry

8. Thermochemistry

Constant-Volume Calorimetry

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Multiple Choice

In a constant-volume calorimetry experiment, the temperature of a bomb calorimeter rises from 25.00°C to 29.00°C when 3.50 g of sucrose is combusted. Given that the heat capacity of the calorimeter is 4.90 kJ/°C, what is the change in internal energy (ΔErxn) for the combustion of sucrose in kJ/mol?

-7000 kJ/mol

-5630 kJ/mol

-3200 kJ/mol

-4500 kJ/mol

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Verified step by step guidance

Identify the known values: the initial temperature (T1) is 25.00°C, the final temperature (T2) is 29.00°C, the mass of sucrose is 3.50 g, and the heat capacity of the calorimeter (Ccal) is 4.90 kJ/°C.

Calculate the temperature change (ΔT) using the formula: ΔT = T2 - T1. Substitute the known values to find ΔT.

Determine the heat absorbed by the calorimeter (qcal) using the formula: qcal = Ccal × ΔT. Substitute the known values to calculate qcal.

Since the calorimeter is at constant volume, the heat absorbed by the calorimeter is equal to the change in internal energy of the reaction (ΔErxn) for the amount of sucrose combusted. Therefore, ΔErxn = -qcal.

Convert the change in internal energy from the amount of sucrose combusted to per mole of sucrose. Use the molar mass of sucrose (C12H22O11), which is approximately 342.30 g/mol, to find ΔErxn in kJ/mol by dividing the calculated ΔErxn by the number of moles of sucrose combusted.