Chemistry - Redox Reactions Question with Solution | TestHub

The reactions are:

1. $\mathrm{HCOOH}\underset{100^{\circ }\mathrm{C}}{\overset{\text{ conc. }{\mathrm{H}}_2{\mathrm{SO}}_4}{\to }}\mathrm{CO}+{\mathrm{H}}_2\mathrm{O}$

2. $5\mathrm{CO}+I_2{O}_5\to 5{\mathrm{CO}}_2+I_2$

3. $I_2+2S_2{O}_3^{2-}\to 2I^{-}+S_4{O}_6^{2-}$

From reaction 1, 1 mole of HCOOH produces 1 mole of CO.

From reaction 2, 5 moles of CO react with 1 mole of I₂O₅ to produce 1 mole of I₂.

From reaction 3, 1 mole of I₂ reacts with 2 moles of S₂O₃²⁻.

For 10 moles of HCOOH:

Moles of CO produced = 10 moles

Moles of I₂ produced from 10 moles of CO = $10molesCO\times \frac{1mole{I}_2}{5molesCO}=2moles{I}_2$

Moles of S₂O₃²⁻ required = $2moles{I}_2\times \frac{2moles{S}_2{O}_3^{2-}}{1mole{I}_2}=4moles{S}_2{O}_3^{2-}$

Therefore, 4 moles of Na₂S₂O₃ are used.