Question

A plate of area 10cm² is to be electroplated with copper (density 9000kg/m³) to a thickness of 10micrometres on both sides, using a cell of 12V. Calculate the energy spent by the cell in the process of deposition. If this energy is used to heat 100g of water, calculate the rise in the temperature of the water. ECE of copper = 3 x 10^-7kg/C and specific heat capacity of water = 4200J/kg-K.

Answer 1

A= 10cm² × 10^–4cm²

t = 10m = 10 × 10^–6

Volume = A(2t) = 10 × 10^–4 × 2 × 10 × 10^–6 = 2 × 10² × 10^–10 = 2 × 10^–8m³

Mass = 2 × 10^–8 × 9000 = 18 × 10^–5kg

W = Z × C =>18 × 10^–5 = 3 × 10^–7 × C

=> q = (18 x 10^-5)/(3 x 10^-7) = 6 x 10²

V= W/q => W = Vq = 12 x 6 x 10² = 76 x 10² = 7.6KJ