Question

I also remembered from general chemistry that there was gold in the ocean. If a very small amount was floating around in the form of Gold(I) sulfate, maybe I could use the principle of oxidation-reduction to recover it?

a) Choose a metal from the activity series, that will replace gold from gold(I) sulfate to elemental gold and write a balanced reaction to illustrate this transformation, including all phase labels

b).Determine the oxidation number of each element and write it below each-reactant and product in your      

       molecular equation above.

c ) Explain which reactant has been oxidized and which reactant has been reduced.

Explain how could you tell?

Answer 1

a)

gold is one of the most "stable" materials, therefore, almos any metal will do

choose Zn/Mg/Cu

Cu(s) + Au2SO4(aq) = Cu2+(aq) + SO4-2(aq) + 2Au(s)

or

Cu(s) + Au2SO4(aq) = CuSO4-2(aq) + 2Au(s)

b)

Cu(s) + Au2SO4(aq) = CuSO4-2(aq) + 2Au(s)

Oxidation state of "solids" ---> 0, since pure

so

Cu = 0, Au = 0

Au in Au2SO4 = +1 (as satte in Gold(I) )

S in SO4-2

S = +6

O in SO4-2 = -2

c ) Explain which reactant has been oxidized and which reactant has been reduced.

Reduction = species that GAINS electrons

Oxidation = process in which a specie will LOSS electrons

Reducing agent = The species that favors reduction, i.e. it will oxidize in order to reduce another species

Oxidizing agent = The species that favors oxidation, i.e. it will reduce in order to oxidise another species

then

Copper is oxidized, loses e-

Gold is reduced, it gains e-