Question

Difficulty: MediumGas Laws and the Ideal Gas Equation

A flexible research balloon is filled with 1.50 m31.50\text{ m}^3 of helium gas at a temperature of 27C27^\circ\text{C}. If the gas is heated at constant pressure until its temperature reaches 127C127^\circ\text{C}, what is the new volume of the balloon?

  1. 2.00 m32.00\text{ m}^3Answer
  2. B
    7.06 m37.06\text{ m}^3
  3. C
    1.13 m31.13\text{ m}^3
  4. D
    1.83 m31.83\text{ m}^3

Answer

The new volume of the balloon is 2.00 m32.00\text{ m}^3.
The answer of 2.00 m32.00\text{ m}^3 correctly uses Charles's Law with absolute temperatures converted to Kelvin (300 K300\text{ K} and 400 K400\text{ K}), showing that heating the gas causes a proportional volume expansion.

Step-by-Step Solution

1
Convert temperatures from Celsius to the Kelvin absolute scale.
T1=27+273=300 KT_1 = 27 + 273 = 300\text{ K}, T2=127+273=400 KT_2 = 127 + 273 = 400\text{ K}.
Gas laws strictly require thermodynamic (absolute) temperature measured in Kelvin.
2
Apply Charles's Law for constant pressure processes.
V1T1=V2T2    V2=V1×T2T1\frac{V_1}{T_1} = \frac{V_2}{T_2} \implies V_2 = V_1 \times \frac{T_2}{T_1}.
Volume is directly proportional to absolute temperature when pressure remains constant.
3
Substitute the known values and calculate V2V_2.
V2=1.50 m3×400 K300 K=2.00 m3V_2 = 1.50\text{ m}^3 \times \frac{400\text{ K}}{300\text{ K}} = 2.00\text{ m}^3.
Simplifying the fraction 400300=43\frac{400}{300} = \frac{4}{3} gives 1.50×43=2.00 m31.50 \times \frac{4}{3} = 2.00\text{ m}^3.

Key Concept

Charles's Law (V1/T1=V2/T2V_1/T_1 = V_2/T_2 at constant pressure)
Estimated Time:1m 15s
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