Question

To expel half the mass of air from a large flask at ${27}^{0}C$, it must be heated to:

• A. ${54}^{0}C$
• B. ${177}^{0}C$
• C. ${277}^{0}C$
• D. ${327}^{0}C$

Answer 1

The correct option is D ${327}^{0}C$

• To expel half the mass of air, we need to double the volume of air so that half of it remains inside the flask. The ideal gas equation contains variables of pressure, volume, no. of moles and temperature.
• At the given conditions, weassume the pressure to be constantand the mass of air is not changing thereforeno. of moles is also constant. Hence, we are left with volume and temperature variables.

According to Charles’ Law: V is directly proportional to T in Kelvin

Therefore, to double the Volume we need to double the Temperature in Kelvin.

We know that, ${27}^{0}C=300K$

$⟹T_2=600K={327}^{0}C$