Solve the following
Question:

When $9.45 \mathrm{~g}$ of $\mathrm{ClCH}_{2} \mathrm{COOH}$ is added to $500 \mathrm{~mL}$ of water, its freezing point drops by $0.5^{\circ} \mathrm{C}$. The dissociation constant of $\mathrm{ClCH}_{2} \mathrm{COOH}$ is $\mathrm{x} \times 10^{-3}$. The value of $\mathrm{x}$ is _____________(Rounded off to the nearest integer) 

$\left[K_{f\left(H_{2} O\right)}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right]$

Solution:

(35)

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Solve the following
Question:

$10.0 \mathrm{ml}$ of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution is titrated against $0.2 \mathrm{M} \mathrm{HCl}$ solution. The following titre values were obtained in 5 readings.

$4.8 \mathrm{ml}, 4.9 \mathrm{ml}, 5.0 \mathrm{ml}, 5.0 \mathrm{ml}$ and $5.0 \mathrm{ml}$ Based on these readings, and convention of titrimetric estimation of concentration of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution is ______________ mM

(Round off to the Nearest integer)

Solution:

(50)

Most precise volume of $\mathrm{HCl}=5 \mathrm{ml}$ at equivalence point Meq. of

$\mathrm{Na}_{2} \mathrm{CO}_{3}=$ meq. of $\mathrm{HCl}$. Let molarity of $\mathrm{Na} 2 \mathrm{CO}_{3}$ solution $=\mathrm{M}$, then

$\mathrm{M} \times 10 \times 2=0.2 \times 5 \times 1$

$\mathrm{M}=0.05 \mathrm{~mol} / \mathrm{L}$

$=0.05 \times 1000$

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