8. Calculate the molarity of solution of ethanol in water in which the

1.	8. Calculate the molarity of solution of ethanol in water in which the mole fraction of ethanol is 0.25 (assume the density of water to be one).
Answer» ANSWER :- Molarity of the solution is 10 M . Explanation :- We have :- → Mole fraction of ETHANOL = 0.25 → Molar mass of ethanol = 46 g/mol → Molar mass of water = 18 g/mol ______________________________ We are GIVEN with 0.25 MOLES of ethanol, so the number of moles of water :- = 1 - 0.25 = 0.75 moles Mass of ethanol :- = No of moles × Molar mass = 0.25 × 46 = 11.5 g Mass of water :- = No of moles × Molar mass = 0.75 × 18 = 13.5 g Mass of the solution :- = (13.5 + 11.5)g = 25 g Volume of the solution :- = Mass/Density = 25/1 = 25 mL = 0.025 L ______________________________ Molarity of the solution :- = Moles of solute/Liters of solution = 0.25/0.025 = 250/25 = 10 M

8. Calculate the molarity of solution of ethanol in water in which the mole fraction of ethanol is 0.25 (assume the density of water to be one).

Answer»

Molarity of the solution is 10 M .

We have :-

→ Mole fraction of ETHANOL = 0.25

→ Molar mass of ethanol = 46 g/mol

→ Molar mass of water = 18 g/mol

______________________________

We are GIVEN with 0.25 MOLES of ethanol, so the number of moles of water :-

= 1 - 0.25

= 0.75 moles

Mass of ethanol :-

= No of moles × Molar mass

= 0.25 × 46

= 11.5 g

Mass of water :-

= No of moles × Molar mass

= 0.75 × 18

= 13.5 g

Mass of the solution :-

= (13.5 + 11.5)g

= 25 g

Volume of the solution :-

= Mass/Density

= 25/1

= 25 mL

= 0.025 L

______________________________

Molarity of the solution :-

= Moles of solute/Liters of solution

= 0.25/0.025

= 250/25

= 10 M