# The volume of gas in a balloon is 1.90 L at 21.0°C. The balloon is heated, causing it to expand to a volume of 5.70 L. What is the new temperature of the gas inside the balloon?

We use old Charles' law.....and get ${T}_{2} = 879.6 \cdot K$....
${V}_{1} / {T}_{1} = {V}_{2} / {T}_{2}$; this assumes a given quantity of gas, and absolute temperatures......
And so....${T}_{2} = {V}_{2} / {V}_{1} \times {T}_{1} = \frac{5.70 \cdot L}{1.90 \cdot L} \times \left(21.0 + 273.13 \cdot K\right)$
=??*K