Acidic Buffer Action

Q.

How is cell potential affected by concentration ?

Q.

pH of a ${10}^{-3}$ M solution of hydrochloric acid will be

1. 1.3

2. 2.0

3. 3.0

4. 4.5

Q.

What is the Amount of heat evolved when $500{\mathrm{cm}}^3$ of $0.2\mathrm{m}{\mathrm{H}}_2{\mathrm{SO}}_4$ is mixed with$200{\mathrm{cm}}^3$ of $0.5\mathrm{m}\mathrm{NaOH}$ solution?

Q. If $K_{sp}$ of $A{g}_{2}C{O}_3$ is, $8\times {10}^{-12}$, the molar solubility of$A{g}_{2}C{O}_3$ in $0.1MAgN{O}_3$ is:

1. $8\times {10}^{-12}M$

2. $8\times {10}^{-10}M$

3. $8\times {10}^{-11}M$

4. $8\times {10}^{-13}M$

Q. The pH of a solution which is $0.1\text{M}$ sodium acetate and $0.01\text{M}$ acetic acid $({\text{pK}}_a=4.74)$ would be:

1. $5.74$
2. $4.74$
3. $4.1$
4. None of these

Q. In blood ($pH=7.4$), aspirin has $p{K}_a$ of 3.4. What is the ratio of $A^{-}$ to $HA$?

1. 1:10000
2. 1000:1
3. 10000:1
4. 100:1

Q.

Identify the parent acids and bases of the following salts. Name each salt. $N{a}_{2}C{O}_3,N{a}_{2}S{O}_4,CaC{O}_3,CuS{O}_4,A{l}_2{\left(S{O}_4\right)}_3$.

Q.

In order to prepare a buffer solution of pH 5.74, sodium acetate is added to acetic acid. If the concentration of acetic acid in the buffer is 1.0 M, the concentration of sodium acetate in the buffer is _________ M. (Round off to the Nearest Integer).

[Given: pK_a (acetic acid) = 4.74]

Q. $100\text{mL}$ of a buffer solution contains $0.1\text{M}$ each of weak acid $HA$ and salt $NaA$. How many grams of $NaOH$ should be added to the buffer so that its pH becomes 6? $(K_a\text{of HA}={10}^{-5})$

1. $\text{0.328 g}$
2. $\text{0.458 g}$
3. $\text{4.19 g}$
4. $\text{3.28 g}$

Q.

Which of the following salts will dissolve in water to produce a solution having a pH below 7?

1. $\mathrm{AgCl}$

2. $\mathrm{KCl}$

3. ${\mathrm{NH}}_4\mathrm{Cl}$

4. $\mathrm{HCl}$

Q. The $pH$ of a blood stream is maintained by a proper balance of $H_{2}C{O}_3$ and $NaHC{O}_3.$ What volume of 5 M $NaHC{O}_3$ solution should be mixed with 10 mL of a sample of solution which is 2.5 M in $H_{2}C{O}_3,$ in order to maintain a $pH=\mathrm{7.4.}$ (Take $p{K}_{a_1}$ for $H_{2}C{O}_3=6.7,log2=0.3,log5=0.7)$

1. 10 mL
2. 25 mL
3. 40 mL
4. 50 mL

Q. Which of the following solutions are isotonic with respect to an aqueous $NaCl$ solution having molarity $0.2M$ and $50\%$ dissociation?

1. $0.3M$ aqueous glucose solution
2. $0.15M$ aqueous $N{a}_{2}S{O}_4$ solution showing complete dissociation
3. $0.15M$ aqueous $KH{F}_2$ solution showing complete dissociation
4. $0.1M$ aqueous $BaC{l}_2$ solution showing $80\%$ dissociation

Q. The ionization constant of a certain weak is ${10}^{-4}.$ What be the [salt] to [acid] ratio if we have to prepare a buffer with pH = 5 using the acid and one of the salts?

1. 1 : 10
2. 5 : 4
3. 10 : 1
4. 4 : 5

Q. An acidic buffer solution can be prepared by mixing solutions of:

1. Ammonium chloride and ammonium hydroxide
2. Sulphuric acid and sodium sulphate
3. Sodium chloride and sodium hydroxide
4. Sodium acetate and acetic acid

Q. What will be the new $pH$ if $0.01mol$ of $HCl$ is added to a $1L$ buffer solution that is $0.02M$ in propionic acid $\left(C{H}_{3}C{H}_{2}COOH\right)$ and $0.015M$ in sodium propionate $\left(C{H}_{3}C{H}_{2}COONa\right)$ ?
Dissociation constant $K_a$ of propionic acid at ${25}^{\circ }C$ is $1.34\times {10}^{-5}$
(Take $log\left(1.34\right)=0.13$)

1. 4.09
2. 4.95
3. 5.15
4. 5.87

Q. What is the pH of the solution when 0.2 mol of $HCl$ is added to one litre of a solution containing 1M acetic acid and acetate ions. Assume that the total volume is one litre. $K_a\left(C{H}_{3}COOH\right)=1.8\times {10}^{-5}$
$log\left(1.8\right)=0.255,log\left(0.66\right)=-0.181$

1. 9.04
2. 4.56
3. 7.2
4. 6.5

Q. How many moles of sodium propionate $\left(C{H}_{3}C{H}_{2}COONa\right)$ should be added to one litre of an aqueous solution containing 0.02 mole of propionic acid$\left(C{H}_{3}C{H}_{2}COOH\right)$ to obtain a buffer solution of $pH=5.87$ ?
Dissociation constant of propionic acid $K_a$ at ${25}^{\circ }C$ is $1.34\times {10}^{-5}$

Take $log\left(1.34\right)=0.13$

1. 0.1 mol
2. 0.2 mol
3. 0.01 mol
4. 0.02 mol

Q. pH of 0.1 M solution of a weak acid (HA) is 4.50. It is neutralised with NaOH solution to decrease the acid content to half of its initial value. Calculate the pH of the resulting solution.

1. 8.00
2. 10.00
3. 4.50
4. 7.00

Q. The rate constants for forward and backward reactions of hydrolysis of ethyl acetate are $1.1\times {10}^{-2}and1.5\times {10}^{-3}mi{n}^{-1}$ respectively. The equilibrium constant for the reaction is

1. 7.33
2. 0.733
3. 0.136
4. 1.36

Q.

An acidic buffer solution can be prepared by mixing the solutions of

1. Sulphuric acid and sodium hydroxide

2. Sodium chloride and sodium hydroxide

3. Ammonium acetate and acetic acid

4. Ammonium chloride and ammonium hydroxide

Q. $100$ mL of $0.01$ M $C{H}_{3}COOH$ and $200$ mL of $0.02$ M $C{H}_{3}COONa$ are mixed to form a buffer solution. $700$ mL of water is added to this solution. The pH before and after dilution are:
(pKa = 4.74, log 4 =0.6)

1. $5.04,5.04$
2. $5.04,0.504$
3. $5.34,0.534$
4. $5.34,5.34$

Q. 1.0 Molar solution of the complex salt, $CrC{l}_3.6H_{2}O$ displays an osmotic pressure of 3 RT. 0.5 L of the same solution will yield (assume $\alpha =1$) 'x' moles of $AgCl$ the value of 'x' is

Q. The $pH$ of a blood stream is maintained by a proper balance of $H_{2}C{O}_3$ and $NaHC{O}_3.$ What volume of 5 M $NaHC{O}_3$ solution should be mixed with 10 mL of a sample of solution which is 2.5 M in $H_{2}C{O}_3,$ in order to maintain a $pH=\mathrm{7.4.}$ (Take $p{K}_{a_1}$ for $H_{2}C{O}_3=6.7,log2=0.3,log5=0.7)$

1. 10 mL
2. 25 mL
3. 40 mL
4. 50 mL

Q. Which of the following mixture which can acts as an acidic buffer solution ?

1. $HCl\text{and}C{H}_{3}COONa$
2. $HN{O}_3\text{and}C{H}_{3}COOH$
3. $H_{2}S{O}_4\text{and}C{H}_{3}COONa$
4. $C{H}_{3}COOH\text{and}C{H}_{3}COONa$

Q. $1\text{L}$ of a buffer solution contains one mole each of $C{H}_{3}COOH$ & ${\left(C{H}_{3}COO\right)}_2\text{Ba}$. Which of the following options are correct? $(p{K}_a\text{of}C{H}_{3}COOH=4.7,\text{log}2=0.3)$

1. pH = 4.7
2. pH = 5
3. pOH = 9
4. pOH = 9.3

Q. To produce a buffer solution that has a pH of 5.270 with already existing solution that contains 10.0 mmol of acetic acid in 1L of solution. How many millimoles of sodium acetate to added to this solutions?
When $p{K}_a$ of acetic acid is 4.752.
$log32.96=1.518$

1. 25
2. 10
3. 23
4. 33

Q. When 100 $mL$ of 1.0 $M$ $HCl$ was mixed with 100 $mL$ of 1.0 $M$ $NaOH$ in an insulated beaker at constant pressure, a temperature increase of ${5.7}^{\circ }C$ was measured for the beaker and its contents (Expt 1). Because the enthalpy of neutralization of a strong acid with a strong base is a constant (-57.0 $kJmo{l}^{-1}$), this experiment could be used to measure the calorimeter constant. In a second experiment (Expt 2), 100 $mL$ of 2.0 $M$ acetic acid $(K_a=2.0\times {10}^{-5})$ was mixed with 100 $mL$ of 1.0 $M$ $NaOH$ (under identical conditions to Expt 1) where a temperature rise of ${5.6}^{\circ }C$ was measured.
(Consider heat capacity of all solutions as $4.2J{g}^{-1}{K}^{-1}$ and density of all solutions as $1.0gm{L}^{-1}$)

The pH of the solution after Expt. 2 is:

1. 2.8
2. 4.7
3. 5
4. 7

Q. A certain buffer solution contains $X^{-}$ is twice the concentration of HX. If $K_a$ for HX is ${10}^{-6},$ then pH of buffer is

1. 7
2. 4.2
3. 6.3
4. 5.8

Q. Calculate the pH of the solution that results from the addition of 0.040 moles of $HN{O}_3$ to a buffer made by combining 0.500 L of 0.380 M $H{C}_3{H}_5{O}_2(K_a=1.30\times {10}^{-5})$ and 0.500 L of 0.380 M $Na{C}_3{H}_5{O}_2.$ Assume addition of the nitric acid has no effect on volume.
$\text{take}log1.30=0.114,log0.652=-0.186$

1. 7
2. 5.65
3. 3.24
4. 4.7

Q. 8g of $NaOH$ was dissolved in 1 L of a solution containing one mole of acetic acid $C{H}_{3}COOH$ and one mole of sodium acetate $C{H}_{3}COONa$. Find the pH of the resulting solution.
The dissociation constant for $C{H}_{3}COOH$ is $1.8\times {10}^{-5}$.

1. 6.88
2. 4.92
3. 3.68
4. 5.76