Question

1) In a copper/lead voltaic cell, which is the anode? Which is the cathode? Explain your reasoning.

2) In your own words, explain the purpose of a salt bridge in an electrochemical cell.

3)Write the balanced chemical equation for the solubility of lead(II) iodide.

4) What is the literature value for the solubility product of lead(II) iodide? (cite an outside source)

5) What is the molar solubility for lead(II) iodide based upon your literature value for the solubility product?

Answer 1

1) In a copper/lead voltaic cell, Cathode is copper and anode is lead.

Cu(s) + Pb^2+ ----------> Cu^2+ + Pb(s)

The reduction potential of Pb(-0.126 V) is smaller than Cu(+0.34 V). Hence, Pb with -ve reduction potential has the ability to accept electrons and Cu with +ve reduction potential have the ability to loose electrons

2) Uses of salt bridge:

i) Salt bridge is used to balance charges in both solutions

ii) It is used to maintain neutrality

iii) To prevent accumilation of ions in both vessels

3) Solubility of PbI2: PbI2(s) ==== Pb^2+(aq) + 2I-(aq)

4) Solubility product, Ksp of PbI2 = 7.9*10^-9

5) Molar solubility = solubilityxmolar mass = 7.9*10^-9*461 g/mol = 3.64*10^-6 g/mol