You mix 44 grams of butane (C4H10) with 60 grams of octane (C8H18). Calculate the mole fraction of butane in this solution, to two significant figures.

Answer 1

Mole fraction butane = moles butane / total moles

moles butane = 44 g C4H10 x 1 mol C4H10 / 58 g = 0.7586 moles butane

moles octane = 60 g C8H18 x 1 mol C8H18 / 114 g = 0.5263 moles octane

Total moles = 0.7586 moles butane + 0.5263 moles octane = 1.285 moles

Mole fraction butane = 0.7586 / 1.285 = 0.59 (2 sig. figs.)