Question

A sample of a gas has a volume of 1380 mL at a temperature of 20.0C what will be it’s volume at 0.0C if the pressure remains constant ?

I’m having a little bit of trouble here setting this up . I have to show all my work

This is what I came up with so far but decided to ask to help

Vi 1380 ML

Ti 20.0

V2 ?

T2 293k

1380 x 293k

Over 760 x 273

Is this even the correct formula ?

Can you please help me understand this problem and show work.

Pv=nRt maybe ?

I appreciate your help very much thanks :)

Answer 1

Ans. Charles’ Law: Volume (V) of a gas in a closed vessel is directly proportional to absolute temperature (T, in kelvin).

That is,            V₁ / T₁ = V₂ / T₂                   - Pressure constant            - equation 1

Note: the temperature must be in terms of “absolute temperature, kelvin”.

Given, T1 = 20.0⁰C = 293.15 K                    ; T2 = 0.0⁰C = 273.15 K

Putting the values in equation 1-

            1380 mL / 293.15 K = V2 / 273.15 K

            Or, V2 = (1380 mL / 293.15 K) x 273.15 K

            Hence, V2 = 1285.85 mL

Therefore, Volume of gas at 0.0⁰C = 1285.85 mL

Note: There is no need of calculating the moles of gas at 20.0⁰C using ideal gas equation (PV = nRT) and then fitting the value of “n” at 0.0⁰C to get new value. Charles’s law jus does the same thing.