assume ideal behavior

Question

1.

A sample of oxygen gas has a density of  g/L at a pressure of 1.11 atm and a temperature of 38°C. Assume ideal behavior.

2.

A sample of an unknown gas is found to have a density of 2.41 g/L at a pressure of 1.06 atm and a temperature of 44°C. The molecular weight of the unknown gas is  g/mol.

Assume ideal behavior.

Answer 1

1). It is assumed that the question is asking for the number of moles of oxygen?

PV = nRT and if we assume we have 1 liter, then we have...

(1.11 atm)(1 L) = n(0.0821 Latm/Kmol)(311K)

n = (1.11)/(0.0821)(311)

n = 0.0435 moles

2). Since we are given the mass, and asked to find the molecular weight, we need to find moles.

Assume we have 1 liter of the gas, and use the ideal gas law...

PV = nRT

n = PV/RT = (1.06 atm)(1 L)/(0.0821 Latm/Kmol)(317K)

n = 0.0407 moles

molecular weight = 2.41 g/0.0407 moles = 59.2 g/mole