Ostwald Dilution Law Mathematical Interpretation

Q.

At ${25}^{\circ }C$, the dissociation constant of a base BOH is $1.0\times {10}^{-12}$. The

concentration of Hydroxyl ions in 0.01 M aqueous solution of the base

would be

1. 2.0 x 10^-6 mol L^-1

2. 1.0 x 10^-5 mol L^-1

3. 1.0 x 10^-6 mol L^-1

4. 1.0 x 10^-7 mol L^-1

Q.

What is the conc. of acetic acid that must be added to 0.5M HCOOH solution so that the dissociation of both acids is the same? [An example of Isohydric solutions] $K_a$ of acetic acid $1.8\times {10}^{-5},K_a$ of formic acid = $2.4\times {10}^{-4}$

1. 4.5 M

2. 3.2 M

3. 6.66 M

4. 12.3 M

Q.

Nicotinic acid (Ka = 1.4 x ${10}^{-5}$) is represented by the formula HNic. For a solution which contains 0.10 mol of nicotinic acid per 2.0 litre of solution, the percent dissociation is:

1. 4.2%

2. 1.66%

3. 3.33%

4. 12.77%

Q. Accumulation of lactic acid $\left(H{C}_3{H}_5{O}_3\right),$ a monobasic acid in tissues leads to pain and a feeling of fatigue. In a 0.10 M aqueous solution, lactic acid is 3.7% dissociates. The value of dissociation constant, $K_a,$ for this acid will be

1. $1.4\times {10}^{-4}$
2. $1.4\times {10}^{-5}$
3. $3.7\times {10}^{-4}$
4. $2.8\times {10}^{-4}$

Q.

A monoprotic acid in 1.00 M solution is 0.01% ionised. The dissociation constant of this acid is

1. 1 X 10^-8

2. 1 X 10^-4

3. 1 X 10^-6

4. 1 X 10^-5

Q.

The dissociation constant of two acids $H{A}_1$ and $H{A}_2$ are $3.14\times {10}^{-4}$ and $1.96\times {10}^{-5}$ respectively. The relative strength of the acids will be approximately

1. 1:4

2. 4:1

3. 1:16

4. 16:1

Q. 0.2 M solution of formic acid is ionized 3.2$\%$, its ionization constant is

1. 
2. 
3. 
4. 

Q.

pH of two solutions :
I. 50 ml of 0.2 M~HCl + 50 ml of 0.2 M HA $(K_a=1.0\times {10}^{-5})$ and
II. 50 ml of 0.2 M HCl + 50 ml of 0.2 M NaA will be respectively

1. 3 and 1

2. 0.70 and 2.85

3. 1 and 2.85

4. 1 and 3

Q. Which of the following has the same pH as 1 L of a 0.1 M $C{H}_{3}COOH$ solution?
$K_a=1.8\times {10}^{-5}$ for $C{H}_{3}COOH$
Take $(1.34{)}^2=1.8$

1. $3mMHCOOH(K_a=6\times {10}^{-4})$
2. $0.1MC{H}_{3}COONa$
3. $1.34mMHCl$
4. $0.1MC{H}_{3}COOH$

Q. Dilution processes of different aqueous solution, with water, are given in LIST-I. The effects of dilution of the solutions on $\left[H^{+}\right]$ are given in LIST -II.
(Note: Degree of dissociation $\left(\alpha \right)$ of weak acid and weak base is << 1; degree of hydrolysis of salt << 1; $\left[H^{+}\right]$ represents the concentration of $H^{+}$ ions)
$\begin{array}{cc}\text{LIST -I}& \text{LIST-II}\\ \text{P. 10 mL of 0.1 M NaOH +20 mL of}& \text{1. The value of}\left[H^{+}\right]\text{does not}\\ \text{0.1 M acetic acid diluted to 60 mL}& \text{change on dilution}\\ \text{Q. 20 mL of 0.1 M NaOH +20 mL of}& \text{2. The value of}\left[H^{+}\right]\text{changes to half}\\ \text{0.1 M acetic acid diluted to 80 mL}& \text{of its initial value on dilution}\\ \text{R. 20 mL of 0.1 M HCl + 20 mL of 0.1}& \text{3. The value of}\left[H^{+}\right]\text{changes to two}\\ \text{M ammonia solution diluted to 80 mL}& \text{times of its initial value on dilution}\\ \text{S. 10 mL saturated solution of}Ni(OH{)}_2& \text{4. The value of}\left[H^{+}\right]\text{changes to}\frac{1}{\sqrt{2}}\\ \text{in equilibrium with excess solid}Ni(OH{)}_2& \text{times of its initial value on dilution}\\ \text{is diluted to 20 mL (solid}Ni(OH{)}_2\text{is still}& \\ \text{present after dilution).}& \\ & \text{5. The value of}\left[H^{+}\right]\text{changes to}\sqrt{2}\\ & \text{times of its initial value on dilution}\end{array}$
Match each process given in LIST -I with one or more effect(s) in LIST -II. The correct option is

1. $P\to 4;Q\to 2;R\to 3;S\to 1$
2. $P\to 4;Q\to 3;R\to 2;S\to 3$
3. $P\to 1;Q\to 5;R\to 4;S\to 1$
4. $P\to 1;Q\to 4;R\to 5;S\to 3$