Question

A 9,00 L tank at 15.2 C is filled with 2.22 g of sulfur tetrafluoride gas and 9.96 R of chlorine pentafluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction of each gas. Round each of your answers to 3 significant digits. mole fraction X 5 ? sulfur tetrafluoride chlorine pentafluoride

Answer 1

Total mass of sulfur tetrafluoride, SF₄ = 2.22 g

Molar mass of SF₄ = 108.07 g/mol

Hence, number of moles of SF₄ can be calculated as

2.22 9 mass molar mass ; 108.07 g/mol 0.02054 mol S

Total mass of chlorine pentafluoride, ClF₅ = 9.96 g

Molar mass of ClF₅ = 130.445 g/mol

Hence, number of moles of ClF₅ can be calculated as

mass Ch's molar mass 9.96 g 130.445 g/mol 0.07635 mol

Hence, the mole fraction of SF₄ can be calculated as

n SF XSF, = - ns + nae 0.02054 mol 0.02054 mol + 0.07635 mol

Since there are only two gases in the mixture, the mole fraction of ClF₅ can be calculated as

Xcuf: = 1 - XSF = 1-0.212 = 0.788

Hence, the answers are

Gas	Mole fraction
sulfur tetrafluoride	0.212
chlorine pentafluoride	0.788

Note: volume and temperature are given to confuse students. It is not needed to calculate the mole fraction of gases.