7.2 litters of an ideal gas are contained at 4.0 atm and 27•C. Using the ideal gas law, calculate how many moles of this gas are present.

The correct answer is 1.17 moles

Explanation:

The ideal gas equation combines the pressure (P), volume (V), temperature (T) and number of moles of a gas (n):

PV= nRT

R is the gas constant (0.082 L.atm/K.mol)

In this case, we have:

V= 7.2 L

P= 4.0 atm

T= 27ºC + 273 = 300 K

We calculate the number of moles (n) of gas as follows:

n= (PV)/(RT)= (4.0 atm x 7.2 L)/(0.082 L.atm/K.mol x 300 K) = 1.17 mol

the product of the pressure and volume is also constant