Multiple Choice
Which event led to the significant increase of oxygen in Earth's atmosphere?
7. Gases
The Ideal Gas Law
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When 0.670 g argon is added to a 500 cm3 container with a sample of oxygen gas, the total pressure of the gases is found to be 1.52 atm at a temperature of 340 K. What is the mass of the oxygen gas in the bulb?
A
0.266 g
B
0.335 g
C
0.621 g
D
0.715 g
E
1.72 g
Verified step by step guidance1
First, use the ideal gas law to find the total number of moles of gas in the container. The ideal gas law is given by \( PV = nRT \), 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.
Convert the volume from cm³ to liters, since the ideal gas constant \( R \) is typically expressed in terms of liters. 500 cm³ is equivalent to 0.500 L.
Rearrange the ideal gas law to solve for \( n \): \( n = \frac{PV}{RT} \). Substitute the known values: \( P = 1.52 \text{ atm} \), \( V = 0.500 \text{ L} \), \( R = 0.0821 \text{ L atm K}^{-1} \text{ mol}^{-1} \), and \( T = 340 \text{ K} \).
Calculate the moles of argon using its mass and molar mass. The molar mass of argon is approximately 39.95 g/mol. Use the formula \( n = \frac{m}{M} \), where \( m \) is the mass and \( M \) is the molar mass.
Subtract the moles of argon from the total moles of gas to find the moles of oxygen. Then, convert the moles of oxygen to mass using the molar mass of oxygen (approximately 32.00 g/mol) with the formula \( m = n \times M \).
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