When electricity (the flow of electrons) is passed through a solution, it causes

Question

When electricity (the flow of electrons) is passed through a solution, it causes an oxidation-reduction (redox) reaction to occur. If the solution contains a metal cation such as Ag+~. the flow of electrons win reduce the silver ion. causing solid silver to plate onto the electrode. The amount of metal plated depends on the number of electrons passed. The total charge of a mole of electrons is 96.485 coulombs (C)and 1 ampere (A) = 1 coulomb/second (C/s) What mass of Cu(s) is electroplated by running 11.5 A of current through a cu^2+ (aq) solution for 4.00 h? Express your answer to three significant figures and include the appropriate unit*. Review the stoichiometry of the reaction. The reaction shows that two moles of electrons are needed for each mole of Cu produced. How many minutes will it take to electroplate 44.1 g of gold by running 5.00 A of current through a solution of Au^+ (aq)? Express your answer to three significant figures and include the appropriate units.

Explanation / Answer

A)

Cu2+ + 2e- ------> Cu

1 mol of Cu requires 2 mol of electron

1 mol of electron = 96485 C

So,1 mol of Cu requires 192970 C

let us calculate to charge passed:

time, t = 14400s

Q = I*t

= 11.50A * 14400s

= 165600.00 C

mol of Cu plated = 165600.00/192970 = 0.86

Molar mass of Cu = 63.55 g/mol

mass of Cu = number of mol * molar mass

= 0.86 * 63.55

= 54.54g

Answer = 54.5 g

B)

Au1+ + 1e- ------> Au

1 mol of Au requires 1 mol of electron

1 mol of electron = 96485 C

So,1 mol of Au requires 96485 C

let us calculate mol of element deposited:

use:

number of mol, n = mass/molar mass

= 44.10/197.00

= 0.22

Now calculate total charge passed

total charge = mol of element deposited * charge required for 1 mol

= 0.22*96485.00

= 21598.93

use:

time = Q/i

= 21598.93/5.00

= 4319.79 seconds

= 72.0 minutes

Answer: 72.0 minute

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