How many coulombs are required to produce i) 80gm of calcium from molten CaCl2 ? [1] ii) 50gm of Aluminum from molten Al2O3 ? [1]

i) Coulombs required to produce 80 g of calcium from molten $\mathrm{CaCl}{}_2$

1. Write the half-reaction for calcium deposition: $$\mathrm{Ca}{}^{2+}+2\mathrm{e}{}^{-}\to \mathrm{Ca}$$ $n=2$ electrons per $\mathrm{Ca}$ ion.

2. Calculate moles of calcium produced: $$\text{Moles of Ca}=\frac{\text{mass}}{\text{molar mass}}=\frac{80\text{g}}{40\text{g/mol}}=2\text{mol}$$

3. Calculate total charge required: $$Q=n\times F\times \text{moles}=2\times 96500\text{C/mol}\times 2=386000\text{C}$$

Answer: 386000 C

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ii) Coulombs required to produce 50 g of aluminum from molten $\mathrm{Al}{}_2\mathrm{O}{}_3$

1. Write the half-reaction for aluminum deposition: $$\mathrm{Al}{}^{3+}+3\mathrm{e}{}^{-}\to \mathrm{Al}$$ $n=3$ electrons per $\mathrm{Al}$ ion.

2. Calculate moles of aluminum produced: $$\text{Moles of Al}=\frac{50\text{g}}{27\text{g/mol}}=1.85\text{mol}$$

3. Calculate total charge required: $$Q=n\times F\times \text{moles}=3\times 96500\text{C/mol}\times 1.85=525450\text{C}$$

Answer: 525450 C