One litre solution of N/2 HCl is heated in a beaker. It was observed that when the volume of the solution is reduced to 600 mL, 3.25 g of HCl is lost. Calculate the normality of the new solution.

One litre solution of N/2 HCl is heated in a beaker. It was observed that when the volume of the solution is reduced to 600 mL, 3.25 g of HCl is lost. Calculate the normality of the new solution.

Answer:

Given Values

Initial Solution

VSol = 1 L or 1000 ml

Normality = 1/2 or 0.5 gm.eq./L

MB = HCl = 1+35.5 = 36.5

Number of H+ = 1

Solution after Heating

VSol = 650 mL

Lost weight of HCl = 3.25 gm

Calculations

Weight of solute (HCl) in initial solution.

WB = \( \frac{Normality \times M_{B} \times V_{Sol~in~L}}{H^{+}} \)

WB = \( \frac{0.5 \times 36.5 \times 1}{1} \) = 18.25 gm

Weight of solute (HCl) left in solution after heating:

WB = 18.25 – 3.25 = 15 gm

Normality of solution after Heating

Normality = \( \frac{W_{B} \times 1000 \times H^{+}}{M_{B} \times V_{Sol~in~ml}} \)

Normality = \( \frac{15 \times 1000 \times 1}{36.5 \times 600} = \frac{150}{219} \) 

Normality = 0.685 gm.eq./L

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