A sample of carbon dioxide gas occuples a volume of 2.5L at standard temperature and pressure (STP). What will be the volume of a sample of argon gas that has the same number of moles and pressure but twice the absolute temperature?

The correct answer is 5.0 L

Explanation:

STP are defined as T=273 K and P= 1 atm

By using the ideal gas equation, we can calculate the number of moles (n) of the gas at a volume V=2.5 L:

PV= nRT

⇒n= (PV)/(RT) =(1 atm x 2,5 L)/(0.082 L.atm/K.mol x 273 K)= 0.112 mol

For a sample of argon gas, with the same number of moles (0.112 mol) but twice the temperature (T = 273 K x 2= 546 K):

V= (nRT)/P = (0.112 mol x 0.082 L.atm/K.mol x 546 K)/1 atm = 5.0 L

That is consistent with the fact that when a gas is heated, it expanses. So, if the temperature increases twice, the volume also increases twice.