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

7. Gases

The Ideal Gas Law: Molar Mass

General Chemistry

7. Gases

The Ideal Gas Law: Molar Mass

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Multiple Choice

To identify a homonuclear diatomic gas, a chemist weighted an evacuated flask with a volume of 3.9 L then filled it with the gas at a pressure of 2.00 atm and 29.0 ºC. The chemist then re-weighted the flask and recorded the difference in mass as 8.81 g. Identify the gas.

H₂

N₂

Cl₂

F₂

O₂

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Verified step by step guidance

First, use the ideal gas law equation: \( PV = nRT \), where \( P \) is the pressure, \( V \) is the volume, \( n \) is the number of moles, \( R \) is the ideal gas constant, and \( T \) is the temperature in Kelvin.

Convert the temperature from Celsius to Kelvin by adding 273.15 to the Celsius temperature: \( T = 29.0 + 273.15 \).

Rearrange the ideal gas law to solve for the number of moles \( n \): \( n = \frac{PV}{RT} \). Substitute the known values: \( P = 2.00 \) atm, \( V = 3.9 \) L, \( R = 0.0821 \) L·atm/mol·K, and \( T \) in Kelvin.

Calculate the molar mass of the gas using the formula: \( \text{Molar mass} = \frac{\text{mass}}{n} \), where the mass is 8.81 g and \( n \) is the number of moles calculated in the previous step.

Compare the calculated molar mass with the molar masses of the given diatomic gases (H2, N2, Cl2, F2, O2) to identify the gas. The gas with the closest molar mass to the calculated value is the correct answer.