Embibe Experts Solutions for Chapter: Equilibrium, Exercise 2: Level 2

Calculate the $\mathrm{pH}$ of a $0.005 \mathrm{M} {\mathrm{Na}}_2\mathrm{S}$ solution. ${\mathrm{K}}_1$ and ${\mathrm{K}}_2$ for ${\mathrm{H}}_2\mathrm{S}$ are $1\times {10}^{-7}$ and $1\times {10}^{-14}$, respectively. Answer correct up to one place of decimal after rounding off.

Tartaric acid is a weak diprotic acid ${\mathrm{H}}_2\mathrm{A}$ with ${\mathrm{K}}_1=1\times {10}^{-3}$ and ${\mathrm{K}}_2=4.6\times {10}^{-5}.$ What is the ${\mathrm{A}}^{2-}$ concentration in $0.025 \mathrm{M} {\mathrm{H}}_2\mathrm{A}$?

If the answer is of type $\mathrm{y}\times {10}^{-5} \mathrm{M}$, report the value of $\mathrm{y}$ correct up to one places of decimal. Assume ${\mathrm{\alpha }}_2\ll {\mathrm{\alpha }}_1$.

A solution is $0.10 \mathrm{M}$ in ${\mathrm{Na}}_2{\mathrm{SO}}_4$. When $50 \mathrm{mL}$ of $0.1 \mathrm{M} \mathrm{Ba}{\left({\mathrm{NO}}_3\right)}_2$ is added to $50 \mathrm{mL}$ of this solution, If the fraction of the sulphate ion is not precipitated is$\mathrm{A} \times {10}^{-4}$, Report the value of A in two significant figures? ${\mathrm{K}}_{\mathrm{sp} }\left({\mathrm{BaSO}}_4\right)$$=1.1\times {10}^{-10}.$

Calculate $\left[{\mathrm{SO}}_4^{2-}\right]$ in $0.15 \mathrm{M} {\mathrm{H}}_2{\mathrm{SO}}_4$ solution if the first step of ionisation is complete and the second step ${\mathrm{K}}_2=1.02\times {10}^{-2}.$

Answer correct up to three places of decimal.

In how many litres of water, $10 \mathrm{g}$ of ${\mathrm{CH}}_3\mathrm{COOH}$ should be dissolved to give $\left[{\mathrm{H}}^{+}\right]={10}^{-3}? {\mathrm{K}}_{\mathrm{a}}\left({\mathrm{CH}}_3\mathrm{COOH}\right)=1.8\times {10}^{-5}?$

An ammonia solution is $9.9 \%$ ammonia by mass and has a density of $0.99 \mathrm{g} {\mathrm{mL}}^{-1}$. Calculate the $\mathrm{pH}$ of the solution ${\mathrm{K}}_{\mathrm{b}}\left({\mathrm{NH}}_4\mathrm{OH}\right)=1.7\times {10}^{-5}$.

Round off to the nearest integer.

What is the $\mathrm{pH}$ of a $1.0\times {10}^{-8} \mathrm{M}$ solution of $\mathrm{NaOH}$?

Answer correct up to two places of decimal.

For the equation ${\mathrm{CaCO}}_3 \left(\mathrm{s}\right)\to \mathrm{CaO} \left(\mathrm{s}\right)+{\mathrm{CO}}_2 \left(\mathrm{g}\right), {\mathrm{K}}_{1000}=0.059.$ Exactly $10 \mathrm{g}$ of ${\mathrm{CaCO}}_3$ is placed in a $10 \mathrm{L}$ container at $1000 \mathrm{K}$. After equilibrium is reached, what mass of ${\mathrm{CaCO}}_3$ remains?

Round off the answer to the nearest integer.