Question

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?

Answer 1

`(P_1V_1)/T_1 = (P_2V_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.

Explanation:

So following the gas law:
#P_2 = (P_1V_1)/T_1 xx T_2/V_2 = (2.50*atmxx900xx10^(-3)cancelLxx336cancelK )/(298cancelKxx450xx10^(-3)cancelL)# `=` `>5*atm ?`

Pressure change is reasonable because we compressing the gas, AND raising the temperature.