Solve Ideal Gas Law Problem: 1.2L Bottle of SO2 at 78PSI, 23°C

[brandon1]

In preparation for a demonstration, your professor brings a 1.2 L bottle of sulfur dioxide into the lecture hall before class to allow the gas to reach room temperature. If the pressure gauge reads 78 psi and the lecture hall is 23°C, how many moles of sulfur dioxide are in the bottle? (Hint: The gauge reads zero when 14.7 psi of gas remains.)

First, I got the P=63.3 and T=296K

PV=nRT
(63.3K)(1.2L)=296nR
75.96=296nR
.25662=nR

Now, how do I get R, or is a always the same value (if so, what is it!) Am I at least heading in the right direction? (Disregard significant figures at the moment)

 

[courtrigrad]

$$R$$ is a constant. It is equaled to 0.08206 atm.l/(mol.K) .

 

[brandon1]

Thank you, I got it!