Ideal Gas Law: Calculate Moles and Mass

Question

A sample of argon gas collected at a pressure of 1.30 atm and a temperature of 25.0 °C is found to occupy a volume of 24.9 liters. How many moles of Ar gas are in the sample? _______ mol

Answer 1

Hello Omar.

This problem is similar to the other one I explained. You will again use the ideal gas law equation PV=nRT where n is the number of moles and R is the universal gas constant. R=0.08206 L atm/(K mol).

Here we are are given: P=1.3atm

V= 24.9 L

T=25C

When we check all of the units with the universal gas constant we see that Temperature is C and we need K for the units to cancel. K=C + 273, so we get 25 + 273= 298K

We need to find moles so we can rearrange the equation PV=nRT to

n = PV/RT

now you can plug the values into the equation:

n= (1.3atm)(24.9L) / (0.08206 L atm/(K mol)) (298K)

I hope this helps. Please let me know if you have any questions or would like to review the topic in more detail.