A solution is made by mixing 55. g of thiophene C4H4S and 65. g of acetyl bromide CH3COBr.

a. Calculate the mole fraction of thiophene in this solution. Round your answer to 2 significant digits.

Mole fraction of C₄H₄S = 0.55

Explanation:

Mole fraction is moles of solute / Total moles

Total moles are the sum of moles of solute + moles of solvent.

Let's find out the moles of our solute and our solvent.

Mass of solute: 55g

Mass of solvent: 65g

Mol = Mass / molar mass

55 g / 84.06 g/mol = 0.654 moles of C₄H₄S

65 g / 123 g/mol = 0.529 moles of C₂H₃BrO

Total moles = 0.654 + 0.529 = 1.183 moles

Mole fraction of thiophene = Moles of tiophene / Total moles

0.654 / 1.183 = 0.55