Chapter 11, Problem 77A

Interpretation Introduction

Interpretation:

Number of moles of Fe(OH)₂ produced on reacting 5 moles of Fe and 8 moles of NiO(OH) to be calculated.

Concept introduction:

Nickel-Iron battery is rechargeable battery discovered by Thomas Edison in 1901.

Answer to Problem 77A

4 moles of Fe(OH)₂ is formed from the reaction. One mole of Fe is left over. It is present in excess amount while NiO(OH) is consumed whole. NiO(OH) is a limiting reagent.

Explanation of Solution

Given information : 5 moles of Fe and 8 moles of NiO(OH) is given.

$\text{Fe+2NiO(OH)+H2O}\to \text{Fe(OH)2+2Ni(OH)2}$

According to stoichiometry of reaction

$\begin{array}{l}1moleofFe\text{}produce=1moleofFe(OH)2\\ 5\times 1moleofFe\text{}produce=5\times 1moleofFe(OH)2\\ 5moleofFe\text{}produce=5moleofFe(OH)2\end{array}$

And

$\begin{array}{l}\text{2}\text{mole}\text{of}\text{NiO(OH)}\text{}\text{produce}\text{=}\text{1}\text{mole}\text{of}\text{Fe(OH)2}\\ \text{1}\text{mole}\text{of}\text{NiO(OH)}\text{}\text{produce}\text{=}\frac{\text{1}}{\text{2}}\text{mole}\text{of}\text{Fe(OH)2}\\ \text{8×1}\text{mole}\text{of}\text{NiO(OH)}\text{}\text{produce}\text{=}\text{8×}\frac{\text{1}}{\text{2}}\text{mole}\text{of}\text{Fe(OH)2}\\ \text{8}\text{mole}\text{of}\text{NiO(OH)}\text{}\text{produce}\text{=}\text{4}\text{mole}\text{of}\text{Fe(OH)2}\end{array}$

The reactant which produce least number of moles is used for calculation and it is the limiting reactant in the reaction.

Conclusion

4 moles of Fe(OH)₂ is formed from the reaction. One mole of Fe is left over. It is present in excess amount while NiO(OH) is consumed whole. NiO(OH) is a limiting reagent.