Question

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

A fixed mass of helium gas is sealed inside a rigid container at a pressure of 2.0 atm2.0\text{ atm} and a temperature of 27C27^\circ\text{C}. If the gas is heated until its pressure reaches 3.5 atm3.5\text{ atm} while maintaining a constant volume, what is its final absolute temperature in Kelvin?

Answer:The final absolute temperature of the gas is 【525】 K.

Answer

The final absolute temperature of the gas is 525 K.
According to Gay-Lussac's Pressure Law, pressure and absolute temperature are directly proportional at constant volume (P1/T1=P2/T2P_1/T_1 = P_2/T_2). First, convert 27C27^\circ\text{C} to absolute temperature: 27+273=300 K27 + 273 = 300\text{ K}. Then substitute the pressures and initial temperature into the equation to find T2T_2: T2=(3.5 atm×300 K)/2.0 atm=525 KT_2 = (3.5\text{ atm} \times 300\text{ K}) / 2.0\text{ atm} = 525\text{ K}.

Step-by-Step Solution

1
Convert the initial temperature from degrees Celsius to the Kelvin scale.
T1=27C+273=300 KT_1 = 27^\circ\text{C} + 273 = 300\text{ K}
All thermodynamic gas law calculations require absolute temperature in Kelvin.
2
Apply the Pressure Law (Gay-Lussac's Law) equation for constant volume.
P1T1=P2T2\frac{P_1}{T_1} = \frac{P_2}{T_2}
The pressure of a fixed mass of gas at constant volume is directly proportional to its absolute temperature.
3
Substitute the given values into the formula and solve for the final temperature T2T_2.
T2=P2×T1P1=3.5×3002.0=525 KT_2 = \frac{P_2 \times T_1}{P_1} = \frac{3.5 \times 300}{2.0} = 525\text{ K}
Multiplying the new pressure by the initial absolute temperature and dividing by the initial pressure yields the final absolute temperature.

Key Concept

Pressure Law (Gay-Lussac's Law of Temperature-Pressure)
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