For an ideal gas:
#PV = nRT#
#P: "bar", "atm", "Pa",#etc.
#V: "L", "dm"^3,#etc.
#n: "mol"#
#T: "K"#
Depending on your units, #R#, the universal gas constant, can take one of the following common forms:
#R = 0.083145 ("L" * "bar")/("mol"*"K")#
#R = 0.082057 ("L" * "atm")/("mol"*"K")#
#R = 8.314472 "J"/("mol"*"K")#
You can use the ratio of #R# as a conversion factor as well if you want. So if you have:
#DeltaH = 51.025 (kJ)/(mol)#
Then:
#DeltaH = ((51.025 cancel("kJ"))/("mol")) ((1000cancel("J"))/(cancel("kJ"))) ((0.083145 "L"*"bar")/(8.314472 cancel("J")))#
#= 510.00 ("L"*"bar")/("mol")#
Keep track of your units. You may have to use a different #R# for different situations. For example, if you are solving for the root-mean-square speed of a gas:
#v_("RMS") = sqrt((3RT)/(M))#
where #R# is #8.314472 "J"/("mol"*"K")#, #T# is in #"K"#, and #M# is the molar mass of a molecule in #(kg)/(mol)#. The reason you would need to use this form is because:
#"J" = "kg"*"m"^2/"s"^2#
