The following question appears on a quiz: ""You fill a tank with gas at 60°C to 100 kPa and seal it. You decrease the temperature to 10°C but keep the volume constant. What happens to the pressure

Pressure will decrease according to the Charles Gay Lussac law.

Explanation:

When there is a gas in a tank, and the moles of gas are not modified, neither the volume, we can notice that pressure will be modifying, in order to the absolute temperature, as directly proportion.

T° increase → Pressure increase

T° decrease → Pressure decrease

If the pressure keeps on constant, it will be the volume that would be modified according to the absolute T°, as a directly proportion.

Volume increase → T° increase

Volume decrease → T° decrease

Let's go to the maths

P₁ / T₁ = P₂/T₂

100 kPa / 333K = P₂ / 283K

(100 kPa / 333K). 283K = P₂ → 84.9 atm

As T° has decreased, pressure also decreased.