Question

Magnesium metal is produced commercially by the isolation of MgCl2 from sea-water followed by electrolysis of molten salt MgCl2  Mg + Cl2 (a) What mass of Mg can be produced if a current of 430A is passed for 1.0h? 4 (b) If a current of 500A is used, how many hours will be required to convert all the 1000 kg of MgCl2 into Mg Metal

Answer 1

Magnesium metal is produced commercially by the isolation of MgCl2 from sea-water followed by electrolysis of molten salt MgCl2  Mg + Cl2.

(a) 192.5 g mass of Mg can be produced if a current of 430A is passed for 1.0h.  

(b) If a current of 500A is used, 1128.6 hours will be required to convert all the 1000 kg of MgCl2 into Mg Metal.

• (a) Given,
• I = 430 A, t = 1 h =3600 sec
• Q=I×t=430×3600=1.548×10^6C
• No.of faradays of charge passed=1.548×10^6 × 96500=16.04F
• Gram equivalent mass of Mg =24.02=12.0g
• On passing charge of 16.04F, mass of Mg produced=12.0 × 1×16.04=192.5 g
• (b) Given,
• I = 500 A, m = 1000kg
• No. of gram equivalents of MgCl2=Mass of MgCl2 Equivalent mass of MgCl2=(106× 47.5)g
• Charge needed for this purpose=106× 47.5×96500  
• Current used in the electrolysis process = 500A
• Time required for the process = 106×96500 × 47.5 × 500=4.063×10^6s
• =4.063×10^6 × 60×60=1128.6hours