Question

Difficulty: EasyGas Laws and the Ideal Gas Equation

A sealed rigid canister contains a fixed mass of nitrogen gas at an initial pressure of 1.50×105 Pa1.50 \times 10^5\text{ Pa} and a temperature of 27C27^\circ\text{C}. If the gas is heated at constant volume until its temperature reaches 127C127^\circ\text{C}, what is the new pressure of the gas?

  1. 2.00×105 Pa2.00 \times 10^5\text{ Pa}Answer
  2. B
    7.06×105 Pa7.06 \times 10^5\text{ Pa}
  3. C
    1.13×105 Pa1.13 \times 10^5\text{ Pa}
  4. D
    3.19×104 Pa3.19 \times 10^4\text{ Pa}

Answer

The new pressure of the gas is 2.00×105 Pa2.00 \times 10^5\text{ Pa}.
At constant volume, the pressure of a gas is directly proportional to its absolute temperature (P1/T1=P2/T2P_1/T_1 = P_2/T_2). Converting temperatures to Kelvin gives 300 K300\text{ K} and 400 K400\text{ K}. Substituting these values yields P2=1.50×105×(400/300)=2.00×105 PaP_2 = 1.50 \times 10^5 \times (400/300) = 2.00 \times 10^5\text{ Pa}.

Step-by-Step Solution

1
Convert the initial and final temperatures from degrees Celsius to Kelvin.
T1=27+273=300 KT_1 = 27 + 273 = 300\text{ K} and T2=127+273=400 KT_2 = 127 + 273 = 400\text{ K}.
Gas laws require absolute temperature in Kelvin for proportional reasoning.
2
Apply Pressure Law (Gay-Lussac's Law) for constant volume.
P1T1=P2T2    P2=P1×T2T1\frac{P_1}{T_1} = \frac{P_2}{T_2} \implies P_2 = P_1 \times \frac{T_2}{T_1}.
At constant volume, the pressure of a fixed mass of gas is directly proportional to its absolute temperature.
3
Substitute the known values into the equation and solve for P2P_2.
P2=1.50×105 Pa×400 K300 K=2.00×105 PaP_2 = 1.50 \times 10^5\text{ Pa} \times \frac{400\text{ K}}{300\text{ K}} = 2.00 \times 10^5\text{ Pa}.
Multiplying initial pressure by the temperature ratio gives the final pressure.

Key Concept

Pressure Law (Gay-Lussac's Law) states that at constant volume, PTP \propto T where TT must be in Kelvin.
Rate this question