Question

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

An aerosol spray can contains a fixed mass of gas at a pressure of 100 kPa100\text{ kPa} and a temperature of 17C17^\circ\text{C}. If the volume of the container remains constant, what is the pressure inside the can when its temperature increases to 307C307^\circ\text{C}?

  1. 200 kPa200\text{ kPa}Answer
  2. B
    106 kPa106\text{ kPa}
  3. C
    1806 kPa1806\text{ kPa}
  4. D
    50 kPa50\text{ kPa}

Answer

The pressure inside the can when heated to 307C307^\circ\text{C} is 200 kPa200\text{ kPa}.
The correct answer is 200 kPa200\text{ kPa}. According to Gay-Lussac's Pressure Law, for a gas at constant volume, pressure is directly proportional to absolute temperature in Kelvin. Converting both temperatures to Kelvin gives T1=290 KT_1 = 290\text{ K} and T2=580 KT_2 = 580\text{ K}. Since absolute temperature doubles, the pressure also doubles from 100 kPa100\text{ kPa} to 200 kPa200\text{ kPa}.

Step-by-Step Solution

1
Convert given temperatures from Celsius to Kelvin.
T1=17C+273=290 KT_1 = 17^\circ\text{C} + 273 = 290\text{ K} and T2=307C+273=580 KT_2 = 307^\circ\text{C} + 273 = 580\text{ K}.
Gas law equations require absolute temperatures in Kelvin.
2
Apply Gay-Lussac's Pressure Law formula at 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}.
Pressure of a fixed mass of gas is directly proportional to its absolute temperature.
3
Substitute the values and calculate the final pressure P2P_2.
P2=100 kPa×580 K290 K=100 kPa×2=200 kPaP_2 = 100\text{ kPa} \times \frac{580\text{ K}}{290\text{ K}} = 100\text{ kPa} \times 2 = 200\text{ kPa}.
Multiplying the initial pressure by the ratio of absolute temperatures gives the final pressure.

Key Concept

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