Question

Difficulty: MediumPressure Law (Gay-Lussac's Law of Temperature-Pressure)

A fixed mass of oxygen gas contained in a rigid metal vessel exerts a pressure of 1.20 atm1.20\text{ atm} at a temperature of 27C27^\circ\text{C}. If the volume of the vessel remains constant, at what absolute temperature in Kelvin (K) will the gas exert a pressure of 1.80 atm1.80\text{ atm}?

Answer: 450 K

Answer

The final absolute temperature of the gas is 450 K450\text{ K}.
According to Gay-Lussac's Pressure Law, for a fixed mass of gas at constant volume, P1T1=P2T2\frac{P_1}{T_1} = \frac{P_2}{T_2}. Converting the initial temperature 27C27^\circ\text{C} to Kelvin gives T1=27+273=300 KT_1 = 27 + 273 = 300\text{ K}. Substituting P1=1.20 atmP_1 = 1.20\text{ atm}, P2=1.80 atmP_2 = 1.80\text{ atm}, and T1=300 KT_1 = 300\text{ K} gives T2=1.80×3001.20=450 KT_2 = \frac{1.80 \times 300}{1.20} = 450\text{ K}.

Step-by-Step Solution

1
Convert the given initial temperature from Celsius to Kelvin.
T1=27+273=300 KT_1 = 27 + 273 = 300\text{ K}
Gas laws require absolute temperature in Kelvin for proportional relationship calculations.
2
State the Pressure Law (Gay-Lussac's Law) equation for a fixed volume of gas.
P1T1=P2T2\frac{P_1}{T_1} = \frac{P_2}{T_2}
The pressure of a fixed mass of gas is directly proportional to its absolute temperature at constant volume.
3
Substitute the given values into the Pressure Law equation.
1.20 atm300 K=1.80 atmT2\frac{1.20\text{ atm}}{300\text{ K}} = \frac{1.80\text{ atm}}{T_2}
Insert P1=1.20 atmP_1 = 1.20\text{ atm}, T1=300 KT_1 = 300\text{ K}, and P2=1.80 atmP_2 = 1.80\text{ atm}.
4
Rearrange and solve for T2T_2.
T2=1.80×3001.20=450 KT_2 = \frac{1.80 \times 300}{1.20} = 450\text{ K}
Cross-multiplying yields the final absolute temperature.

Key Concept

Pressure Law (Gay-Lussac's Law)
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