Answer:
[tex]\boxed{\text{2.0 g}}[/tex]
Explanation:
1. Write the equation for the half-reaction.
Mg²⁺ + 2e⁻ ⟶ Mg
The number of electrons transferred (z) is 2 mol per mole of Mg.
2. Calculate the number of coulombs
Q = It
[tex]\text{t} = \text{90 min} \times \dfrac{\text{60 s}}{\text{1 min}} = \text{5400 s}\\\\Q = \text{3 C/s} \times \text{ 5400 s} = 16 000 C[/tex]
3. Mass of Mg
We can summarize Faraday's laws as
[tex]m = \dfrac{QM}{zF}\\\begin{array}{rcl}m & = &\dfrac{16 000 \times 24.30}{2 \times 96 485}\\& = & \textbf{2.0 g}\\\end{array}\\\text{The mass of Mg deposited is }\boxed{\textbf{2.0 g}}[/tex]
