Chemistry, asked by gouravnayak2456, 8 months ago

A chalk sample exactly requires 200 ml of 7.3% (w/w) HCl solution of
specific gravity 1.2, for complete reaction with all CaCo, present in
it. If the chalk sample is 72% pure, the mass of sample taken is :
(A) 100 gm
(B)200/3 gm
(C)50/3 gm
(D)100/3gm

Answers

Answered by abhi178

Given info : A chalk sample exactly requires 200 ml of 7.3% (w/w) HCl solution of specific gravity 1.2, for complete reaction with all CaCO₃ , present in it. If the chalk sample is 72% pure.

To find : initial amount of sample .

Solution : specific gravity of HCl solution = 1.2

so density of HCl solution , d = 1.2 g/cm³

Molar mass of HCl = 36.5 g/mol

now molarity of HCl = % w/W × 10 × d/M

= 7.3 × 10 × 1.2/36.5

= 2.4

Now no of moles of HCl = molarity × volume of solution

= 2.4 × 200/1000

= 0.48

Now for complete reaction,

equivalents of CaCO3 = equivalents of HCl

⇒mass of CaCO3/(equivalent weight of CaCO3) = mass of HCl/(equivalent weight of HCl)

⇒x/(50) = 0.48 × 36.5/(36.5)

⇒x = 50 × 0.48 = 24 g

But sample of chalk is 72% pure

So, weight of chalk × 72 % = 24g

⇒weight of chalk = 24 × 100/72 = 100/3

Therefore 100/3 g of sample of chalk is taken.

Answered by Anonymous

Answer :-

Given info : A chalk sample exactly requires 200 ml of 7.3% (w/w) HCl solution of specific gravity 1.2, for complete reaction with all CaCO₃ , present in it. If the chalk sample is 72% pure.

To find : initial amount of sample .

Solution : specific gravity of HCl solution = 1.2