Embibe Experts Solutions for Chapter: Redox Reactions, Exercise 4: EXERCISE-4

A sample containing ${\mathrm{Na}}_2{\mathrm{CO}}_3 \& \mathrm{NaOH}$ is dissolved in $100 \mathrm{mL}$ solution. $10 \mathrm{mL}$ of this solution requires $25 \mathrm{mL}$ of $0.1 \mathrm{N} \mathrm{HCl}$ when $\mathrm{Ph}$ is used as indicator. If $\mathrm{MeOH}$ is used as indicator $10 \mathrm{mL}$ of same solution requires $30 \mathrm{mL}$ of same $\mathrm{HCl}$. Calculate $\%$ of ${\mathrm{Na}}_2{\mathrm{CO}}_3$ and $\mathrm{NaOH}$ in the sample.

Potassium acid oxalate ${\mathrm{K}}_2{\mathrm{C}}_2{\mathrm{O}}_4·3{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4·4{\mathrm{H}}_2\mathrm{O}$ can be oxidized by ${{\mathrm{MnO}}_4}^{-}$ in acid medium. Calculate the volume of $0.1 \mathrm{M} {\mathrm{KMnO}}_4$ reacting in acid solution with one gram of the acid oxalate.

What amount of substance containing $60\%\mathrm{NaCl}, 37\%\mathrm{KCl}$ should be weighed out for analysis so that after the action of $25 \mathrm{mL}$ of $0.1 {\mathrm{NAgNO}}_3$ solution, excess of ${\mathrm{Ag}}^{+}$ is back titrates with $5 \mathrm{mL}$ of ${\mathrm{NH}}_4\mathrm{SCN}$ solution. Given that $1 \mathrm{mL}$ of ${\mathrm{NH}}_4\mathrm{SCN}=1.1. \mathrm{mL}$ of ${\mathrm{AgNO}}_3$.

A volume of $12.53 \mathrm{mL}$ of $0.05093 \mathrm{M} {\mathrm{SeO}}_2$ reacted with exactly $25.52 \mathrm{mL}$ of $0.1 \mathrm{M} {\mathrm{CrSO}}_4$. In the reaction, ${\mathrm{Cr}}^{2+}$ was oxidized to ${\mathrm{Cr}}^{3+}$. To what oxidation state was selenium converted by the reaction.

$5 \mathrm{g}$ sample of brass was dissolved in one litre dil. ${\mathrm{H}}_2{\mathrm{SO}}_4.20 \mathrm{mL}$ of this solution were mixed with $\mathrm{KI}$, liberating ${\mathrm{I}}_2$ and ${\mathrm{Cu}}^{+}$ and the ${\mathrm{I}}_2$ required $20 \mathrm{mL}$ of $0.0327 \mathrm{N}$ hypo solution for complete titration. Calculate the percentage of $\mathrm{Cu}$ in the alloy.

$0.84 \mathrm{g}$ iron ore containing $\mathrm{x}$ percent of iron was taken in a solution containing all the iron in ferrous condition. The solution required $\mathrm{x} \mathrm{mL}$ of a dichromatic solution for oxidizing the iron content to ferric state. Calculate the strength of dichromatic solution.

$50 \mathrm{g}$ of a sample of $\mathrm{Ca}(\mathrm{OH}{)}_2$ is dissolved in $50 \mathrm{mL}$ of $0.5 \mathrm{NHCl}$ solution. The excess of $\mathrm{HCl}$ was titrated with $0.3 \mathrm{N}$ - $\mathrm{NaOH}$. The volume of $\mathrm{NaOH}$ used was $20 \mathrm{cc}$. Calculate $\%$ purity of $\mathrm{Ca}(\mathrm{OH}{)}_2$.

One $\mathrm{g}$ of impure sodium carbonate is dissolved in water and the solution is made up to $250 \mathrm{mL}$. To $50 \mathrm{mL}$ of this made up solution, $50 \mathrm{mL}$ of $0.1 \mathrm{N}-$$\mathrm{HCl}$ is added and the mix after shaking well required $10 \mathrm{mL}$ of $0.16 \mathrm{N}-\mathrm{NaOH}$ solution for complete titration. Calculate the $\%$ purity of the sample.