Core Practical 10: Construct electrochemical cells and measure electrode potentials

Question 1

zinc sulfate is

Answer 1

harmful

Question 2

1.0 mol dm-3 iron(II) sulfate is

Answer 2

harmful

Question 3

potassium nitrate is

Answer 3

oxidising

Question 4

the method this experiment is:

Answer 4

-clean the strips of zinc, copper, iron and silver with sandpaper

for the [Zn(s) | Zn2+(aq)] and [Cu2+(aq) | Cu(s)] system:

-pour 50cm3 of 1.0 mol dm-3 solution of each metal sulfate (use 0.1 mol dm-3 silver nitrate for the silver) into separate beakers and label
-plug two wires into a high resistance voltmeter and clip the ends to the strip of zinc and the other to the strip of copper
-place the wired strips into their complimentary solutions (e.g. Cu(s) in the CuSO4(aq))
-place a salt bridge made up of filter paper soaked in saturated potassium nitrate solution (KNO3)
-record the voltage (if a negative value is displayed, swap the connections so that a positive value is obtained
-repeat for the following metal combinations:
[Zn(s) | Zn2+(aq)] and [Fe2+(aq) | Fe(s)]
[Fe(s) | Fe2+(aq)] and [Cu2+(aq) | Cu(s)]
[Zn(s) | Zn2+(aq)] and [Ag+(aq) | Ag(s)]
[Cu(s) | Cu2+(aq)] and [Ag+(aq) | Ag(s)]

Question 5

why is 0.1 mol dm-3 silver nitrate used instead of 1.0 mol dm-3 silver nitrate?

Answer 5

-silver nitrate is highly oxidising and very expensive

Question 6

silver nitrate is

Answer 6

highly oxidising