What happens when NH₄Cl is added to an aqueous solution of NH₄OH?

1. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions decreases.

2. Concentration of $\left[{\mathrm{OH}}^{-}\right]$ ions increases.

3. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions as well as concentration $\left[{\mathrm{OH}}^{-}\right]$ ions increase.

4. Concentration of $\left[{\mathrm{NH}}_4^{+}\right]$ ions decreases.

500 ml of 0.2 M HCl is mixed with 500 ml of 0.2 M CH₃COOH. 25 ml of the mixture is titrated with 0.1 M NaOH solution. By how many units does the pH change from the start to the stage when HCl is just completely neutralized. K_a for acetic acid$=2.0\times {10}^{-5}$.

1. 3.7

2. 4.4

3. 2.0

4. 3.0

When 60 ml of 0.1 M $\mathrm{Ca}{\left({\mathrm{NO}}_3\right)}_2$ is mixed with 40 ml of 0.125 M ${\mathrm{Na}}_2{\mathrm{CO}}_3$, ${\mathrm{CaCO}}_3$ precipitates. If K_sp of ${\mathrm{CaCO}}_3$ is $5\times {10}^{-9}$, then $\left[{\mathrm{CO}}_3^{2-}\right]$ in the resulting solution is

1. $5\times {10}^{-8} \mathrm{M}$

2. $5\times {10}^{-9} \mathrm{M}$

3. $5\times {10}^{-6} \mathrm{M}$

4. $5\times {10}^{-7} \mathrm{M}$

100 ml of 0.3 M NH₄OH is mixed with 100 ml of 0.2 M NaOH. K_b NH₄OH is $1.8\times {10}^{-5}$. The degree of dissociation of NH₄OH is

1. $1.02\times {10}^{-2}$

2. $1.8\times {10}^{-5}$

3. $1.8\times {10}^{-4}$

4. $1.02\times {10}^{-4}$

The ionization constant  of $\left[{\mathrm{NH}}_4^{+}\right]$ in water is $5.6\times {10}^{-10}$ at $25°\mathrm{C}$. The rate constant for the reaction of $\left[{\mathrm{NH}}_4^{+}\right]$ and $\left[{\mathrm{OH}}^{-}\right]$ to form NH₃ and H₂O is $3.4\times {10}^{10} \mathrm{lit} {\mathrm{mol}}^{-1 }{\sec }^{-1}$ at $25°\mathrm{C}$. The rate constant for the proton transfer from water to NH₃ in $\mathrm{lit} {\mathrm{mol}}^{-1} {\sec }^{-1}$ is

1. $6.07\times {10}^5$

2. $6.07\times {10}^{-5}$

3. $6.07\times {10}^{-3}$

4. $6.07\times {10}^{-4}$

The equilibrium constant of ${\mathrm{NH}}_4^{+}$ to NH₃ and H⁺ is 10^-10. The rate constant for ${\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}\to {\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}$ is 10¹⁰. The rate constant for ${\mathrm{NH}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{NH}}_4^{+}+{\mathrm{OH}}^{-}$ is:

1. ${10}^5$

2. ${10}^{20}$

3. ${10}^8$

4. ${10}^9$

An acid base indicator has ${\mathrm{K}}_{\mathrm{a}}=3\times {10}^{-5}$. The acid form of the indicator is red and the basic form is blue. By how much must the pH change in order to change the indicator from 75% red to 75% blue (log 3=0.4770)

1. 0.95

2. 2.3

3. 0.75

4. 5

The dissociation constants for aniline, acetic acid and ionic product of water at $25°\mathrm{C}$ are $3.83\times {10}^{-10}, 1.75\times {10}^{-5} \mathrm{and} 1.008\times {10}^{-14}$ respectively. The degree of hydrolysis of aniline acetate in a decinormal solution is

1. 0.56%

2. 55%

3. 5.6%

4. 2.75%

A solution of benzoic acid (a weak monobasic acid) is titrated with NaOH. The pH of the solution is 4.2 when half of the acid is neutralized. The dissociation constant of the acid will be:

1. $3.2\times {10}^{-5}$

2. $6.42\times {10}^{-4}$

3. $6.31\times {10}^{-5}$

4. $8.7\times {10}^{-8}$

The mixture that shows the maximum buffer capacity is:

1. $0.1 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}+0.2 \mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

2. $0.1 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}+0.15 \mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

3. $0.05 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}+0.15 \mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$

4. $0.1 \mathrm{M} {\mathrm{CH}}_3\mathrm{COOH}+0.12 \mathrm{M}\hspace{0.17em}{\mathrm{CH}}_3\mathrm{COONa}$