Question

A gas occupies a volume of 120. mL at 27°C. At what temperature in °C would the volume be 80.0mL?

Answer 1

To answer this question we will assume the following:

• The amount of gas is constant, that is, the moles do not change.

,

• The pressure remains constant.

,

• The gas behaves like an ideal gas.

With these assumptions, we can apply Charles's law which tells us:

`(V_1)/(T_1)=(V_2)/(T_2)`

Where,

V1 is the initial volume of the gas in liters, 120mL=0.120L

T1 is the initial temperature in Kelvin, 27°C+273.15K=300.15K

V2 is the final volume of the gas in liters, 80.0mL=0.080L

T2 is the final temperature in Kelvin, unknown.

We clear T2 and replace the known data:

`T_2=(T_1)/(V_1)* V_2`
`\begin{gathered} T_2=(300.15K)/(0.120L)*0.080L=200.1K \\ T_2=-73.1\degree C \end{gathered}`

Answer: The gas would have a volume of 80.0mL at -73.1°C