Question

3.6 g NaCI is dissolved in 340 grams of water. Calculate the mole fraction of both the solute and solvent?

Answer 1

Answer:

N_NaCl=n_NaCl/(n_NaCl+n_H2O)-mole fraction of NaCl,

N_H2O=n_H2O/(n_NaCl+n_H2O)-mole fraction of H₂O.

n_NaCl=m_NaCl/M_NaCl=3.6g/(23g*mol^-1+35.5g*mol^-1)=0.06mol

n_H2O=m_H2O/M_H2O=340g/(2*1g*mol^-1+16g*mol^-1)=18.89mol

N_NaCl=0.06/(18.89+0.06)=0.003 or 0.3%

N_H2O=18.89/(18.89+0.06)=0.997 or 99.7%

So, the mole fraction of NaCl is 0.3% and the mole fraction of

H₂O is 99.7%.