Start out by balancing the equation
SiO
2 + XeF
6-> XFO
4 + SiF
4You are trying to solve for p, so you need the other variables
V is given as the volume of the container: 1.00 L
n is the number of moles of gas. You calculate molar mass by adding up the atomic masses of the elements in the compound (found on most periodic tables). Find this number for XeF
6 then divide 2.00 by this number to get the number moles of Xenon hexafluoride. Then you can use the balanced equation to find how many moles of Silicon hexafluoride you produced.
R is a constant you should be able to find in any chemistry book or on a website (I don't have it memorized, unfortunately
)
T is 25+273=298K
Once you find all those it's simple algebra to figure out.
Now, I'm not sure what you mean by not knowing too much, so if you have trouble balancing the equations or understanding anything else I mentioned (especially in finding n) then don't be afraid to ask.