A chemical reaction produced a 0.311 g sample of gas which occupied 225 mL at 55 C exerting a pressure of 886 mm Hg. What is the molar mass of the gas?

Answer 1

you will have to use this two formulas
p*V=n*R*T
n=m/M

p*V=(m/M)*R*T
p*V*M=m*R*T
M=(m*R*T)/P*V

then just make sure you convert units right
(i hope i did convert them right, if not then correct me)

M=(0.311g*8.314L kPa*328.15K)/(mol*K*118.124 kPa*0.225L)
M=31.924 g/mol