Calculating mole fraction in a gas mixture

Question

a 6.00 L tank at -28C is filled with 5.35 g of sulfur hexafluoride gas and 2.54g of sulfur tetrafluoride gas. You can assume both gasses behave as ideal gasses under these conditions. Calculate the mole fraction of each gas. 

 

sulfur Hexafloride:

 

sulfur tetraflurode: 

Answer 1

Sulfur tetrafluoride = SF4  molar mass 108 g/mol

Sulfur hexafluoride = SF6 molar mass 146 g/mol

 

moles SF6 = 5.35 g x 1 mole/146 g = 0.03664 moles

moles SF4 = 2.54 g x 1 mole/108 g = 0.02352 moles

Total moles of gas = 0.03664 moles + 0.02352 moles = 0.06016 moles

Mole fraction SF6 = 0.03664/0.06016 = 0.609

Mole fraction SF4 = 0.02352/0.06016 = 0.391

NOTE: The information concerning the volume (6.00 L) and the temperature (-28C) are not relevant to this particular problem.