Question

Calcium is obtained industrially by electrolysis of molten cacl2 and is used in aluminum alloys. how many coulombs are needed to produce 13.3 g of ca metal? if a cell runs at 15 a, how many minutes will it take to produce 13.3 g of ca(s)?

Answer 1

64 000 C; 71 min

Step-by-step explanation:

1. Number of coulombs

a. Write the equation for the half-reaction.

Ca²⁺ + 2e⁻ ⟶ Ca

b. Calculate the moles of Ca

Moles of Ca = 13.3 g Ca × (1 mol Ca/40.08 g Ca) = 0.3318 mol Ca

c. Calculate the moles of electrons

Moles of electrons = 0.3318 mol Ca × (2 mol electrons/1 mol Ca) = 0.6637 mol electrons

d. Calculate the number of coulombs

No. of coulombs = 0.6637 mol electrons × (96 485 C/1 mol electrons)

= 64 000 C

It takes 64 000 C to produce 13.3 g of Ca.

2. Time required

Q = It

t = Q/I = 64 000 C/15 C·s⁻¹ = 4270 s

t = 4270 s × 1 min/60 s = 71 min

The process will take 71 min.