Text Box: Chromium Electroplating

Text Box: Anode mass decreases: Cr (s) ® Cr 3+ (aq) + 3 e- Cathode mass increases Cr3+ (aq) + 3 e- ® Cr (s) Eo = - 0.74 v Cr plates on the inert cathode electrode. Electroplating is important in protecting objects from corrosion

Text Box: Electrolytic Cell: Nonspontaneous— a power source forces the flow of electrons What voltage is needed?

Text Box: Quantifying Electroplating

•The Problem:

Calculate the mass of Chromium metal that will be electroplated if a current of 0.75 A is run for 5.0 minutes.

Information Needed to Solve the Problem:

•1 ampere (A) =  1 Coulomb per second         or          1 A = 1 C / s

•            The charge of 1 mol of electrons is 96,500 C = 1 Faraday     or           96,500 C / 1 mol e-

•            Cr3+ ( aq) + 3 e- ® Cr (s).

•             3 mol of electrons will plate 1 mol of Cr

•             Molar Mass of Cr:   52.0 g/mol

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  Answer to the Problem: 0.040 g Cr