Gas Law Chemistry

Question

1) How many liters are occupied by 1.05 mol of nitrogen at 198◦C and 0.564 atm pressure?

2) A gas sample occupies 4.71 L at 39◦C. What is the pressure given that there are 1.18 mol of gas in the sample?

Answer 1

1) First itemize the information given: P=0.564 atm; n=1.05 mol; T=(198+273) K; asked about volume V

Need the Ideal gas law PV=nRT (note R will be 0.0821 L.atm/mol.K because pressure is in atm)

Rearranging the equation to solve for V gives V=nRT/P

V= (1.05 mol)(0.0821 L.atm/mol.K)(471K) / 0.564 atm

= 80.0 Liters

2) Using similar method as above now we are being asked about pressure. Since the unit for pressure was not mentioned we have a choice of the value used for R (gas constant. Remember this can be 0.0821 L.atm/mol.K or 62.4 L. torr/mol.K)

Here V=4.71L; T= (39+273) K ; n=1.18 mol ; R = 0.0821 L.atm/mol.K

P= (1.18 mol)(0.0821L.atm/mol.K)(312K) / 4.71 L

= 6.42 atm