# A man heats a balloon in the oven. If the balloon initially has a volume of 4 liters and a temperature of 20°C, what will the volume of the balloon be after he heats it to a temperature of 250°C?

We use old Charles' Law. to get approximately $7 \text{L}$.
Since, for a given quantity of gas, $V \propto T$ if $P$ is constant, $V = k T$.
Solving for $k$, ${V}_{1} / {T}_{1} = {V}_{2} / {T}_{2}$, and ${V}_{2} = \frac{{V}_{1} \times {T}_{2}}{T} _ 1$; $T$ is reported in $\text{degrees Kelvin}$, $V$ may be in whatever units you like, $\text{pints, sydharbs, gills, bushels etc.}$. Of course, we stick with sensible units, i.e. $L , \text{ litres}$.
Thus ${V}_{2}$ $=$ $\frac{4 \text{L} \times \left(250 + 273\right) K}{\left(20 + 273\right) K}$ $\cong$$7 \text{L}$