Question

An unknown metal strip was placed in H2SO4. Use data table to determine identity of metal and its molar mass. Show all work.

InitialMass: 9.3698g

FinalMass: 9.4443g

Avg.Current:0.5263A

Time:3mins

FaradaysConstant: 96548 C/mol e-

NFactor:2electrons

Answer 1

According to faraday's 1st law of electrolysis:

The amount of chemical change produced by the current at an electrode-electrolyte boundary is proportional to the quantity of electricity used. Here chemical change means the amount of metal deposited.

Faraday's laws can be summarized by

$m=\frac{QM}{Fn}$

where:

• m is the mass of the substance liberated at an electrode in grams
• Q is the total electric charge passed through the substance in coulombs
• F = 96548 C mol−1 is the Faraday constant
• M is the molar mass of the substance in grams per mol
• n electrons transferred per ion

In electrolysis,$Q=It$ , where I is the current in Amperes and t is time in seconds

$m=\frac{ItM}{Fn}$

$(9.4443-9.3698)=\frac{0.5263\times (3\times 60)\times M}{96548\times 2}$

$M=\frac{0.0745\times 96548\times 2}{0.5263\times (3\times 60)}=151.9\ g/mol$

The metal that has this particular atomic weight is Europium $(Eu_{63}^{151.9})$ .