Electrolysis of 200 mL of a solution of an unknown metal increased the cathode mass by 0.0434 grams when a current of 0.50 A passed through the cell for 5 minutes.Further research determined the charge on the metal to be +2.What is the identity of the metal?

Question

Quizplus · Accepted Answer

The metal is iron (Fe) because the amount of metal deposited during electrolysis can be calculated using Faraday's laws of electrolysis. The mass (m) of a substance deposited at an electrode is given by $m = \frac{MIt}{nF}$, where $M$ is the molar mass of the substance, $I$ is the current in amperes, $t$ is the time in seconds, $n$ is the number of moles of electrons required to deposit one mole of the substance (the charge on the metal ion), and $F$ is Faraday's constant (approximately $96485 \, C \, mol^{-1}$). Given that the charge on the metal is +2, $I = 0.50 \, A$, $t = 5 \, minutes = 300 \, seconds$, and $m = 0.0434 \, g$, we can solve for $M$.Rearranging the formula to solve for $M$, we get $M = \frac{m \cdot n \cdot F}{I \cdot t}$.Plugging in the values: $M = \frac{0.0434 \cdot 2 \cdot 96485}{0.50 \cdot 300}$, we find that $M$ is approximately 56 g/mol, which is the molar mass of iron (Fe), indicating that the unknown metal is iron.

Electrolysis of 200 ML of a Solution of an Unknown