Buffer solutions and their pH — practice questions

Question 1 · difficulty L2 · understanding

$\mathrm{K}_{\mathrm{a}}$ for $\mathrm{CH}_3 \mathrm{COOH}$ is $1.8 \times 10^{-5}$ and $\mathrm{K}_{\mathrm{b}}$ for $\mathrm{NH}_4 \mathrm{OH}$ is $1.8 \times 10^{-5}$. The $\mathrm{pH}$ of ammonium acetate solution will be _________.

Question 2 · difficulty L2 · understanding

The $$\mathrm{pH}$$ of an aqueous solution containing $$1 \mathrm{M}$$ benzoic acid $$\left(\mathrm{pK}_{\mathrm{a}}=4.20\right)$$ and $$1 \mathrm{M}$$ sodium benzoate is 4.5. The volume of benzoic acid solution in $$300 \mathrm{~mL}$$ of this buffer solution is _________ $$\mathrm{mL}$$. (given : $$\log 2=0.3$$)

Question 3 · difficulty L2 · understanding

$$600 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{HCl}$$ is mixed with $$400 \mathrm{~mL}$$ of $$0.01~\mathrm{M} ~\mathrm{H}_{2} \mathrm{SO}_{4}$$. The $$\mathrm{pH}$$ of the mixture is ___________ $$\times 10^{-2}$$. (Nearest integer) [Given $$\log 2=0.30$$ $$\log 3=0.48$$ $$\log 5=0.69$$ $$\log 7=0.84$$ $$\log 11=1.04]$$

Question 4 · difficulty L2 · understanding

Millimoles of calcium hydroxide required to produce 100 mL of the aqueous solution of pH 12 is $$x\times10^{-1}$$. The value of $$x$$ is ___________ (Nearest integer). Assume complete dissociation.

Question 5 · difficulty L2 · understanding

The dissociation constant of acetic acid is $$x\times10^{-5}$$. When 25 mL of 0.2 $$\mathrm{M~CH_3COONa}$$ solution is mixed with 25 mL of 0.02 $$\mathrm{M~CH_3COOH}$$ solution, the pH of the resultant solution is found to be equal to 5. The value of $$x$$ is ____________

Question 6 · difficulty L2 · understanding

$$\mathrm{K}_{\mathrm{a}}$$ for butyric acid $$\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{COOH}\right)$$ is $$2 \times 10^{-5}$$. The $$\mathrm{pH}$$ of $$0.2 \,\mathrm{M}$$ solution of butyric acid is __________ $$\times 10^{-1}$$. (Nearest integer) [Given $$\log 2=0.30$$]

Question 7 · difficulty L2 · understanding

pH value of 0.001 M NaOH solution is ____________.

Question 8 · difficulty L2 · understanding

50 mL of 0.1 M CH 3 COOH is being titrated against 0.1 M NaOH. When 25 mL of NaOH has been added, the pH of the solution will be _____________ $$\times$$ 10 $$-$$2 . (Nearest integer) (Given : pK a (CH 3 COOH) = 4.76) log 2 = 0.30 log 3 = 0.48 log 5 = 0.69 log 7 = 0.84 log 11 = 1.04

Question 9 · difficulty L2 · understanding

The pH of a solution obtained by mixing 50 mL of 1 M HCl and 30 mL of 1 M NaOH is x $$\times$$ 10 $$-$$4 . The value of x is ____________. (Nearest integer) [log 2.5 = 0.3979]

Question 10 · difficulty L2 · understanding

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 : pKa (acetic acid) = 4.74]