Answer to Question #165119 in General Chemistry for Sage Topaz

Question

A sample of rubbing alcohol contains 142 g of isopropyl alcohol (C₂H₇OH) and 58 g of water. What are the mole fractions of alcohol and water?

Answer 1

moles of isopropyl alcohol = 142/60.01 = 2.36moles

moles of water = 58/18 = 3.22moles

For isopropyl alcohol C₃H₇OH

$\frac{2.36 moles C_3H_7OH}{2.36 moles C_3H_7OH+3.22 moles H_2O}$ = 0.423

For water

$\frac{3.22 moles H_2O}{2.36 moles C_3H_7OH+3.22 moles of H_2O}$ = 0.577

Mole fraction of C₃H₇OH is 0.423 and H₂O is 0.577