Question

How many moles of ${{{C}}_2}{{{O}}_4}^{2 - }$ ions will be oxidized by one mole of ${{Mn}}{{{O}}_4}^ - $?
A. $\dfrac{1}{2}$
B. $\dfrac{3}{2}$
C. $\dfrac{5}{2}$
D. $\dfrac{7}{2}$

Answer 1

Hint: A mole is simply a unit of measurement. One mole of a molecule has $6.02 \times {10^{23}}$ atoms. This particular number is called Avogadro number. Relative atomic mass of an element in the periodic table is the mass of one mole of that atom. In the case of molecules, composition is given by its molecular formula.

Complete step by step answer:
Concentration is the amount of solute dissolved in a given amount of solution. There are different types of concentration units. Formula and molecular mass deal with individual atoms and molecules. Mole is the unit that relates the number of particles and mass.
It is given that number of moles of permanganate, ${{{n}}_{{{Mn}}{{{O}}_4}^ - }} = 1$
The oxidation of oxalate ions with permanganate ions is represented in the chemical equation given below:
$2{{Mn}}{{{O}}_4}^ - + 5{{{C}}_2}{{{O}}_4}^{2 - } + 16{{{H}}^ + } \to 2{{M}}{{{n}}^{2 + }} + 10{{C}}{{{O}}_2} + 8{{{H}}_2}{{O}}$
The given equation is balanced.
So we can say that the prefix before the chemical formula represents the number of moles of that compound.
Thus two moles of permanganate reacts with five moles of oxalate ions to give 2 moles of ${{Mn}}$ (II), ten moles of carbon dioxide and eight moles of water molecules. Thus manganese is reduced and oxalate is oxidized.
Based on stoichiometry of the chemical equation,
Two moles of permanganate ions oxidizes five moles of oxalate ions. So one mole of permanganate ion needs $\dfrac{5}{2} = 2.5{{mol}}$ of oxalate ions to oxidize.
So $2.5$ moles of oxalate ions will be oxidized by one mole of permanganate ions

So, the correct answer is Option C.

Additional information:
Mole concepts enable us to solve stoichiometric problems involving mass relations of reactants and products in chemical reactions.


Note: Moles provide a bridge from molecular scale to real-world scale. One mole of molecules or formula units contain Avogadro number times the number of atoms or ions of each element in the compound. Each chemical equation provides information about the amount of reactants produced.