Question:
If 4 g of NaOH dissolves in 36 g of H2O, calculate the mole fraction of each
component in the solution. Also, determine the molarity of the solution (specific
gravity of solution is 1g mL–1).
Solution:
Mole fraction of H2O = No; of moles of H2O/ Total no: of moles (H2O+NaOH)
No: of moles of H2O = 36/18=2moles
No: of moles of NaOH = 4/40=0.1mol
Total no: of moles = 2+0.1= 2.1
Mole fraction of H2O = 2/2.1 = 0.952
Mole fraction of NaOH = 0.1/2.1 = 0.048
Mass of solution = Mass of H2O + Mass of NaOH = 36+4=40G
Volume of the solution = 40/1 = 40mL
Molarity = 0.1/0.04 = 2.5M
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