Question

How many faradays of electricity are required to produce 6g of Mg from $MgC{l_2}$.

Answer 1

Hint: Magnesium cation formed by the dissociation of magnesium chloride in water gains two electrons to form magnesium by the process of electrolysis. To calculate the mass of magnesium moles of magnesium is multiplied by the molecular weight of magnesium.

Complete step by step answer:
The magnesium chloride is salt which on dissolving in water dissociates into magnesium cation and chloride anion.
The reaction is shown below.
$MgC{l_2} \to M{g^{2 + }} + C{l^ - }$
In this reaction, magnesium chloride dissociates to give magnesium cation with +2 oxidation state and chloride ion with -1 oxidation state.
The reaction is shown below.
$M{g^{2 + }} + 2{e^ - } \to Mg$
The magnesium ion gain two electrons during electrolysis to form magnesium
1 mole of magnesium needs 2 faradays of electricity.
The mass is calculated by the formula as shown below.
$m = n \times M$
Where,
m is the mass of the compound.
n is the moles of the compound.
M is the molecular weight of the compound.
The molecular weight of magnesium is 24 g/mol.
To calculate the mass of magnesium, substitute the values of moles and molecular weight in the above equation.
$\Rightarrow m = 1mol \times 24g/mol$
$\Rightarrow m = 24g$
1 mole of magnesium is equal to 24 g magnesium.
So, 24 g of magnesium requires 2 faraday of electricity.
Thus, 6 g of magnesium contains
$\Rightarrow \dfrac{{2 \times 6}}{{24}}$
$\Rightarrow \dfrac{{12}}{{24}}$
$\Rightarrow 0.5$
Thus, 6 g of magnesium requires 0.5 faraday.
1 Faraday is equal to 96500 coulomb. So, 0.5 faraday is equal to 48250 C.

Note: In the given question, we need to find the amount of electricity to form 6g of Mg from $MgC{l_2}$. So we need to form magnesium atoms from magnesium ion which is released by dissolving magnesium chloride in water. By the method of electrolysis, magnesium ion is reduced to form magnesium.