How many grams of chromium metal are plated out when a constant current of 8.00 A is passed through an aqueous solution containing Cr³⁺ ions for 160.minutes? A)13.8 g B)24.6 g C)41.2 g D)124 g

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Quizplus · Accepted Answer

The amount of chromium plated out can be calculated using Faraday's laws of electrolysis. The mass of a substance deposited or liberated at an electrode is directly proportional to the quantity of electricity that passes through the electrolyte. The quantity of electricity (Q) can be calculated as current (I) times time (t), where time must be in seconds. Therefore, Q = I * t = 8.00 A * (160 min * 60 s/min) = 76800 C. The molar mass of chromium (Cr) is approximately 52 g/mol, and it has a valency of 3 in the Cr^3+ ion, meaning 3 moles of electrons are required to reduce 1 mole of Cr^3+ to Cr metal. The charge of one mole of electrons (Faraday constant) is approximately 96485 C/mol. Therefore, the mass of chromium plated can be calculated using the formula: mass = (Q * M) / (n * F), where M is the molar mass of chromium, n is the number of moles of electrons required (valency), and F is the Faraday constant. Substituting the values, we get mass = (76800 C * 52 g/mol) / (3 * 96485 C/mol) ≈ 13.8 g.

How Many Grams of Chromium Metal Are Plated Out When