20   mL of calcium hydroxide was consumed when it was reacted with 10   mL of unknown solution of…

20 mL of calcium hydroxide was consumed when it was reacted with 10 mL of unknown solution of H2SO4. Also 20 mL standard solution of 0.5 M HCl containing 2 drops of phenolphthalein was titrated with calcium hydroxide, the mixture showed pink colour when burette displayed the value of 35.5 mL whereas the burette showed 25.5 mL initially. The concentration of H2SO4 is _______M. (Nearest integer)

Solution

Titration principle is N1V1=N2V2

N = Normality

V = Volume of solution

M1V1n1=M2V2n2

M = molarity

n = Valence factor of acid or base

As pink colour is obtained on consumption of 10 ml of Ca(OH)2, we have

20×0.5×1=10×M×2

Molarity of Ca(OH)2=1020=12M

Also, moles of Ca(OH)2=mm of H2SO4

12×20=10×M

Molarity of H2SO4=1M

Asked in: JEE Main 2023 (13 Apr Shift 1)

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