Increasing the temperature of a gas from 30 C to 60 C will increase its volume by approximately:
A. 0 percent (no volume change)
B. 5 percent
C. 10 percent
D. 50 percent
E. 100 percent
Commentary
For flow measurement purposes, Charles’ Law is often used to calculate the change in volume that occurs when temperature changes:
V / V0 = T / T0
where V is volume and T is the absolute temperature. In this application, T0 is approximately 300 Kelvins (273+30) and T is approximately 330 Kelvins (273+60). The new volume is therefore approximately 1.1 times (330/300) times the old volume, so the new volume is about 10 percent greater than the old volume. Therefore, the correct answer is Answer C.
Additional complicating factors
Charles’ Law was used above assuming that the gas is ideal. If the gas is not ideal, other methods can be employed to account for non-linearity and pressure effects on density such as the Non-Ideal Gas Law, density tables, or other such techniques. In actual applications, remember that the composition of the gas can change and affect these calculations.
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