IB Physics Short Note Temperature and Density

A question from Thermodynamics exam

A sample of an ideal gas is compressed by a piston from 10 m3 to 5 m3 and simultaneously cooled from 273 degrees C to 0 degrees C. As a result there is:
A. an increase in pressure
B. a decrease in pressure
C. a decrease in density
D. no change in density
E. an increase in density

Reasoning
Density refers to the mass per unit volume. First condition describes the decrease in volume, therefore density increases. Second condition describes the decrease in temperature. Base on kinetic molecular theory, molecules are closer together as energy is removed from the matter. Again, the volume decreases.

Answer
E. is the correct answer, stating “an increase in density”.

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