molecular weight is?

Question

1.

A 2.41 gram sample of an unknown gas is found to occupy a volume of 1.53 L at a pressure of 452 mm Hg and a temperature of 39°C. The molecular weight of the unknown gas is  g/mol.

2.

A 3.68 gram sample of an unknown gas is found to occupy a volume of 1.53 L at a pressure of 805 mm Hg and a temperature of 44°C. The molecular weight of the unknown gas is  g/mol.

Answer 1

1). PV = nRT and we can solve for n (moles)

P = 452 mm Hg x 1 atm/760 mm Hg = 0.5947 atm

V = 1.53 L

R = 0.0821 Latm/Kmol

T = 39 + 273 = 312K

n = (0.5947)(1.53)/(0.0821)(312)

n = 0.0355 moles

molecular weight = mass/moles = 2.41 g/0.0355 moles = 67.9 g/mole

2). Do this the same way as #1, after converting 805 mm Hg to atm and 44 degrees C to K.