Answer:
6e⁻
Explanation:
Charge in reducing 2 mole of Cr⁶⁺ to Cr³⁺
Cr⁶⁺ + xe⁻ → Cr³⁺
The numbers 6+ and 3+ on the chromium atoms are the oxidation number of the atom.
It shows the number of electrons that has been lost by chromium in an oxidation state.
Cr⁶⁺ shows that it has lost 6 electrons. When an atom loses electrons, the number of protons becomes more. This makes it positively charged in nature.
This analogy goes for Cr³⁺
Therefore, in going from reactants to products, chromium
6+ → 3+
In this kind of expression, the number of atoms must be conserved and the charges too;
2Cr⁶⁺ + xe⁻ → 2Cr³⁺
given 2 moles of Cr;
To balance the charge;
2(6+) + x(-) = 2(3+)
12 - x = 6
x = 6
A charge of 6e⁻ is required to reduce 2 mole of Cr⁶⁺ to Cr³⁺
