Embibe Experts Solutions for Chapter: Redox Reactions, Exercise 1: EXERCISE-1

A $0.518 \mathrm{g}$ sample of limestone is dissolved in $\mathrm{HCl}$ and then the calcium is precipitated as ${\mathrm{CaC}}_2{\mathrm{O}}_4.$ After filtering and washing the precipitate, it requires $40.0 \mathrm{mL}$ of $0.250 {\mathrm{NKMnO}}_4$ solution acidified with ${\mathrm{H}}_2{\mathrm{SO}}_4$ to titrate it as. The percentage of $\mathrm{CaO}$ in the sample is :-

${\mathrm{MnO}}_4^{-}+{\mathrm{H}}^{+}+{\mathrm{C}}_2{\mathrm{O}}_4^{2-}⟶{\mathrm{Mn}}^{2+}+{\mathrm{CO}}_2+2{\mathrm{H}}_2\mathrm{O}$

Calculate the mass of anhydrous oxalic acid, which can be oxidised to ${\mathrm{CO}}_2\left(\mathrm{g}\right)$ by $100 \mathrm{ml}$ of an ${\mathrm{MnO}}_4^{-}$ solution, $10 \mathrm{ml}$ of which is capable of oxidising $50 \mathrm{ml}$ of $1\mathrm{N} {\mathrm{I}}^{-}$ to ${\mathrm{I}}_2.$

A mixture of ${\mathrm{NaHC}}_2{\mathrm{O}}_4$ and ${\mathrm{KHC}}_2{\mathrm{O}}_4.{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4$ required equal volumes of $0.2 \mathrm{N} {\mathrm{KMnO}}_4$ and $0.12 \mathrm{N} \mathrm{NaOH}$ separately. What is the molar ratio of ${\mathrm{NaHC}}_2{\mathrm{O}}_4$ and ${\mathrm{KHC}}_2{\mathrm{O}}_4.{\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4$ in the mixture?

To a $10 \mathrm{ml} 1 \mathrm{M}$ aqueous solution of ${\mathrm{Br}}_2,$ excess of $\mathrm{NaOH}$ is added so that all ${\mathrm{Br}}_2$ is disproportional to $\mathrm{Br}$ and${{\mathrm{BrO}}_3}^{-}.$ The resulting solution is freed from ${\mathrm{Br}}^{-},$ by extraction and excess of ${\mathrm{OH}}^{-}$ neutralised by acidifying the solution. The resulting solution is sufficient to react with $1.5 \mathrm{gm}$ of impure ${\mathrm{CaC}}_2{\mathrm{O}}_4\left(\mathrm{M}=128 \mathrm{gm} {\mathrm{mol}}^{-1}\right)$ample. The $\%$ purity of Oxalate sample is

The relevant reactions are  ${\mathrm{Br}}^2\left(\mathrm{aq}.\right)+{\mathrm{OH}}^{-} \to {\mathrm{Br}}^{-}\left(\mathrm{aq}.\right)+\mathrm{Br}{{\mathrm{O}}_{{}^3}}^{-}$

${\mathrm{BrO}}_3{}^{-}+{\mathrm{C}}_2{\mathrm{O}}_4{}^{2-}\to \mathrm{Br}+{\mathrm{CO}}_2$

What is the equivalent weight of ${\mathrm{H}}_2{\mathrm{SO}}_4$ in the reaction?

${\mathrm{H}}_2{\mathrm{SO}}_4+\mathrm{Nal}\to {\mathrm{Na}}_2{\mathrm{SO}}_4+{\mathrm{I}}_2+{\mathrm{H}}_2 \mathrm{S}+{\mathrm{H}}_2\mathrm{O}$

$25 \mathrm{mL}$ of $0.50{\mathrm{MH}}_2{\mathrm{O}}_2$ solution is added to $50 \mathrm{mL}$ of $0.20{\mathrm{MKMnO}}_4$ in acid solution. Which of the following statement are true :-

${\mathrm{H}}_2{\mathrm{O}}_2$ acts as both oxidising as well as reducing agent. As oxidising agent, its product is ${\mathrm{H}}_2\mathrm{O},$ but as reducing agent, its product is ${\mathrm{O}}_2.$ Volume strength has great significance for chemical reactions.

The strength of  $\text{'}10\mathrm{V}\text{'}$ means $1$ volume (or litre) of ${\mathrm{H}}_2{\mathrm{O}}_2$ on decomposition $\left({\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}+\frac{1}{2}{\mathrm{O}}_2\right)$ gives $10$ volume (or litre) of oxygen at $\mathrm{NTP}.$

$15\mathrm{gmBa}{\left({\mathrm{MnO}}_4\right)}_2$ sample containing inert impurity is completely reacting with $100 \mathrm{ml}$ of $\text{'}11.2 \mathrm{V}\text{'}{\mathrm{H}}_2{\mathrm{O}}_2,$ in acidic medium then what will be the $\%$ purity of $\mathrm{Ba}{\left({\mathrm{MnO}}_4\right)}_2$ in the sample?

(Atomic mas $\mathrm{Ba}=137, \mathrm{Mn}=55$)

What mass of ${\mathrm{H}}_2( \mathrm{g})$ is needed to reduce $192 \mathrm{gm}$ of ${\mathrm{MoO}}_3$ to metal ? [At. wt. of $\mathrm{Mo}=96$]