If 37.5 mol of an ideal gas occupies 38.5 Lat 85.00°C, what is the pressure of the gas?

1 Answer
Oct 31, 2016

Answer:

#P~=29*atm#

Explanation:

#P=(nRT)/V# #=# #(37.5*cancel(mol)xx0.0821*cancelL*atm*cancel(K^-1)*cancel(mol^-1)xx358.15*cancelK)/(38.5*cancelL)#

Note that the equation is consistent dimensionally. We wanted an answer in #"atmospheres"# and we got one.

When we do equations like this, the gas constant #R# can have many different values, each with different units. For chemists, probably the most useful one is #R=0.0821*L*atm*K^-1*mol^-1#. These need not be learned, because they will appear as supplementary material on the exam paper. They do have to be used correctly.