Question

A 2.50 L flask contains a sample of ideal gas. The gas us then cooled to a temperature of 19.00 degrees Celsius and the volume of the gas is measured to be 1.75 L. If the temperature remains constant, what is the intial temperature of the gas?

Answer 1

In question it is mentioned "If the temperature remains constant"

It should be "If the pressure remains constant". Since you asked for initial temperature, so teemperature is not constant.

Now,

Charles' law states that when the pressure on a sample of an ideal gas is held constant, the Kelvin temperature and the volume will be directly related.

So,

V1/T1 = V2/T2

T1 = V1T2/V2 ----------------------------------------(1)

Given,

T2 = 19 ^oC = (273 + 19) K = 292 K

V2 = 1.75 L

V1 = 2.5 L

T1 = ?

Substituting the values in equation (1), we get;

T1 = (2.5 L) (292 K) / (1.75 L)

= 417 K

= (417 - 273) ^oC

= 144 ^oC