required practical 8: measuring the EMF of an electrochemical cell

Question 1

method of this experiment

Answer 1

clean the zinc and copper strips with emery paper
place copper in a beaker with copper sulfate solution - 1moldm3
place zinc in a beaker with zinc sulphate solution - 1moldm3
use strip of filter paper soaked in potassium nitrate solution as the salt bridge
connect copper and zinc metal to high resistance voltmeter using wires and crocodile clips

Question 2

what is the purpose of the salt bridge

Answer 2

used to connect the circuit, allowing movement of ions to maintain charge

Question 3

why can you not use potassium chloride for the salt bridge

Answer 3

the chloride can react the copper ions forming complexes

Question 4

method for comparative electrode potentials

Answer 4

clean copper metal with emery paper
connect positive terminal of the voltmeter to the copper using a wire and crocodile clip
use filter paper soaked with sodium chloride and place ont op of the copper metal
connect a different metal to the voltmeter and hold against the filter paper
repeat with different metals and compare electrode potentials