Question

How many grams of copper will be plated out by a current of 2.3 a applied for 35 minutes to a 0.50 m solution of copper (ii) sulfate?

Answer 1

To find the mass of copper plated by electrolysis, calculate the total charge using the current and time, then convert this to moles of copper using Faraday's constant, and finally multiply by the molar mass of copper to get the mass. Approximately 1.5875 grams of copper will be plated out.

Step-by-step explanation:

The calculation of the mass of copper plated out during electrolysis involves Faraday's laws of electrolysis. The amount of substance that is deposited or dissolved at an electrode during electrolysis is directly proportional to the quantity of electricity (charge) passed through the substance. Using the given current and time, we can calculate the total charge passed and then determine the moles of copper that will be plated out.

First, convert the time from minutes to seconds: 35 minutes × 60 seconds/minute = 2100 seconds.

Then, calculate the total charge (Q) using the formula: Q = It (where I is current and t is time). So, Q = 2.3 A × 2100 s = 4830 coulombs.

One mole of electrons corresponds to a charge of approximately 96485 coulombs (Faraday's constant), and since it takes two moles of electrons to plate out one mole of Cu (copper ions are Cu²⁺), the charge required to plate out one mole of copper is 2 × 96485 coulombs.

Now we can calculate the moles of copper plated:

moles Cu = (total charge)/(2 × Faraday's constant)

moles Cu = 4830 C / (2 × 96485 C/mol) ≈ 0.025 moles of Cu

Finally, to find the mass of copper, we multiply the moles by the molar mass of Cu:

mass of Cu = moles Cu × molar mass of Cu

mass of Cu = 0.025 mol × 63.5 g/mol ≈ 1.5875 grams

Thus, approximately 1.5875 grams of copper will be plated out.

Answer 2

when the magnitude of the charge Q = I*T

when we have I current = 2.3

and T = 35 min * 60 = 2100 s

by substitution:

∴ Q = 2.3 * 2100

= 4830 C

according to this reaction equation:

Cu2+ + 2e- → Cu

we can see that 1 mol Cu2+ need 2 mol e- to produce Cu

mol of electron e- = Q / faraday's constant

= 4830 / 96485

= 0.05 mol

when 1 mol Cu2+ → 2 mol e-

?? ← 0.05 mol

∴ moles Cu2+ = 0.05 /2 = 0.025 mol

∴ mass Cu2+ = moles Cu2+ * molar mass Cu2+

= 0.025 * 64

= 1.6 g