# What current would be required to deposit 2.08 m2 of chrome plate having a thickness of 0.037 mm in 4.50 hr from a solution of H2CrO4?

What current would be required to deposit 2.08 m2 of chrome plate having a thickness of 0.037 mm in 4.50 hr from a solution of H2CrO4?

The density of chromium is 7.19 g cm-3.

Relevance

CrO₄²⁻(aq) + 8H⁺(aq) + 6e⁻ → Cr(s) + 4H₂O(l)

Mole ratio e⁻ : Cr = 6 : 1

Volume of Cr deposited = (2.08 × 100² cm²) × (0.037/10 cm) = 76.96 cm³

Mass of Cr deposited = (76.96 cm³) × (7.19 g cm⁻³) = 553.3 g

Molar mass of Cr = 52.0 g/mol

Moles of Cr = (553.3 g) / (52.0 g/mol) = 10.64 mol

Moles of e⁻ = (10.64 mol) × 6 = 63.84 mol

Each mole of electrons carries 96485 C of electricity.

Current required = (63.84 mol) × (96485 C/mol) / (4.50 × 3600 s) = 380 C/s = 380 A

OR:

(2.08 × 100² cm² Cr) × (0.037/10 cm Cr) × (7.19 g Cr / 1 cm³ Cr) × (1 mol Cr / 52.00 g Cr) × (6 mol e⁻ / 1 mol Cr) × (96485 C / 1 mol e⁻) / (4.50 × 3600 s)

= 380 C/s

= 380A

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