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

Thermochemical Equations

General Chemistry

8. Thermochemistry

Thermochemical Equations

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Multiple Choice

Sodium metal reacts with water to produce hydrogen gas and sodium hydroxide according to the chemical equation shown below. When 0.025 mol of Na is added to 100.00 g of water, the temperature of the resulting solution rises from 25.00°C to 35.75°C. If the specific heat capacity of water is 4.18 J/g°C, what is the enthalpy change (ΔH) for the reaction per mole of Na?

-75 kJ/mol

-150 kJ/mol

-445 kJ/mol

-250 kJ/mol

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Verified step by step guidance

Write the balanced chemical equation for the reaction: \( 2 \text{Na} + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2 \).

Calculate the heat absorbed 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.

Substitute the given values into the formula: \( m = 100.00 \text{ g} \), \( c = 4.18 \text{ J/g°C} \), and \( \Delta T = 35.75°C - 25.00°C \).

Calculate the enthalpy change per mole of Na by dividing the total heat absorbed by the number of moles of Na used in the reaction. Use the formula \( \Delta H = \frac{q}{n} \), where \( n \) is the number of moles of Na.

Ensure the sign of \( \Delta H \) reflects the exothermic nature of the reaction, as the temperature of the solution increases, indicating heat is released.