# A sample of helium gas has a volume of 900 milliliters and a pressure of 2.50 atm at 298 K. What is the new pressure when the temperature is changed to 336 K and the volume is decreased to 450 milliliters?

Nov 25, 2015

$\frac{{P}_{1} {V}_{1}}{T} _ 1 = \frac{{P}_{2} {V}_{2}}{T} _ 2$ This is the combined gas law. And it saves us from tedious mucking about with gas constants and having to standardize units.
P_2 = (P_1V_1)/T_1 xx T_2/V_2 = (2.50*atmxx900xx10^(-3)cancelLxx336cancelK )/(298cancelKxx450xx10^(-3)cancelL) $=$ >5*atm ?