Question

Çonsider the following equations:

$2{\mathrm{Fe}}^{2+}+{\mathrm{H}}_2{\mathrm{O}}_2\to \mathrm{xA}+\mathrm{yB}$ (in basic medium)

$2{{\mathrm{MnO}}_4}^{-}+6{\mathrm{H}}^{+}+5{\mathrm{H}}_2{\mathrm{O}}_2\to \mathrm{x}\text{'}\mathrm{C}+\mathrm{y}\text{'}\mathrm{D}+\mathrm{z}\text{'}\mathrm{E}$ (in acidic medium)

The sum of the stoichiometric coefficients $\mathrm{x},\mathrm{y},\mathrm{x}\text{'},\mathrm{y}\text{'}$ and $\mathrm{z}\text{'}$for products $\mathrm{A},\mathrm{B},\mathrm{C},\mathrm{D}$ and $\mathrm{E}$, respectively, is _____________.

Answer 1

To determine the sum of stoichiometric coefficients, we have to determine the values of stoichiometric coefficients and for this, we have to frame the chemical equations given:

For First reaction:

Step 1: The first equation: $\left[{\mathrm{Fe}}^{2+}\to {\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}\right]\times 2\_\_\_\_\_\left(1\right)$ ${\mathrm{H}}_2{\mathrm{O}}_2+2{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}\to 2{\mathrm{H}}_2\mathrm{O}\mathrm{\_\_\_\_\_\_\_}\left(2\right)$

Step 2: On adding equations $\left(1\right)$ and $\left(2\right)$. we get: $2{\mathrm{Fe}}^{2+}+{\mathrm{H}}_2{\mathrm{O}}_2+2{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}\to 2{\mathrm{Fe}}^{3+}+2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{e}}^{-}$

Step 3: Hence, it can be observed from the equation that: $x=2$ and $y=2$.

For second reaction:

Step 1: Similarly, the second equation is: $\left[8{\mathrm{H}}^{+}+{{\mathrm{MnO}}_4}^{-}+5{\mathrm{e}}^{-}\to {\mathrm{Mn}}^{2+}+4{\mathrm{H}}_2\mathrm{O}\right]\times 2\_\_\_\_\_\_\left(3\right)$ $\left[{\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{O}}_2+2{\mathrm{H}}^{+}+2{\mathrm{e}}^{-}\right]\times 5\_\_\_\_\_\_\left(4\right)$

Step 2: On adding equations $\left(3\right)$ and $\left(4\right)$ we get: $2{{\mathrm{MnO}}_4}^{-}+5{\mathrm{H}}_2{\mathrm{O}}_2+16{\mathrm{H}}^{+}+10{\mathrm{e}}^{-}\to 2{\mathrm{Mn}}^{2+}+8{\mathrm{H}}_2\mathrm{O}+5{\mathrm{O}}_2+10{\mathrm{H}}^{+}+10{\mathrm{e}}^{-}$

Step 3: Hence it can be observed from the equation that: $x\text{'}=2,y\text{'}=8$ and $\mathrm{z}\text{'}=5$.

Step 4: The sum of stoichiometric coefficients $=2+2+2+8+5=19$.

Therefore the sum of stoichiometric coefficients is $19$.