Question

What is the mole fraction of ethanol in a solution made by dissolving 29.2 g of ethanol, C₂H₅OH, in 53.6 g of water?

	0.176
	0.213
	0.545
	0.352

Answer 1

Given mass of ethanol = 29.2 g

Molar mass of C₂H₅OH is = (2xAt.mass of O )+(6XAt.mass of H)+(1x At.mass of O)

                                      = (2x12) + (6x1)+(1x16)

                                      = 46 g/mol

Number of moles of C₂H₅OH is , n₁ =

Given mass of water , H₂O is = 53.6 g

Molar mass of H₂O is = (2xAt.mass of H)+(1x At.mass of O)

                                 = (2x1) +(1x16)

                                 = 18 g/mol

Number of moles of C₂H₅OH is , n₂ =

So total number of moles , N = n1 + n2

                                          = 0.635 + 2.98

                                          = 3.615 moles

Mole fraction of ethanol ,