General chemistry Electrochemistry

[299678]

Q. During the electrolysis of an aqueous solution of CuSO4 using inert electrodes.
a) the anode loses mass and the cathode gains mass
b) the mass of the anode decreases but the mass of the cathode remains constant
c) the mass of the anode remains the same, but the cathode gains mass
d) the anode and the cathode neither gain nor lose mass.

Q. Fluoride ion in aqueous solution are difficult to oxidize at the anode of an electrolytic cell because
a) the aqueous solutions of fluoride are nonconducting
b) it is impossible to find the proper material from which to build the electrodes
c) the fluorides are not very soluble
d) oxygen is released from water in preference to fluorine

Q. In which case would the least number of faradays of electricity be required for the liberation of 1.0 g of free metals?

a) K from molten KOH
b) Na from molten NaCl
c) CU from aqueous CuSO4
d) Ag from aqueous AgNO3

Q. Which products are formed during the electrolysis of a concentrated aqueous solution of sodium chloride?

I. Cl2(g) II, NaOH (aq) III H2(g)

a) I only
b) I and II
c) I and III
d) I, II, III

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[loveoforganic]

1) C or D. They're inert. Nothing happens to them. If anything, metal would deposit on the cathode, but in that case the cathode isn't technically gaining mass, because the deposited metal isn't part of the cathode, it's just attached. Poor question, semantics.

2) Fluoride is much harder to fluorine than water is to oxygen. Electronegativities. D.

3) You're looking for the heaviest metal, so that you produce the least moles of metal and thus require the least moles of electrons. Silver is the heaviest, it's D. Cu2+ is both lighter and requires twice as many electrons to reduce to metal.

4) It depends on the voltage applied, but I think C is the correct answer. The other possible products would be sodium hypochlorite and oxygen.

 

[sfoksn]

kyle, coudl you please post the solutions? thank you.