Half cells Flashcards
1
Q
PD cannot be measured directly, how is the circuit completed? Why is this done?
A
- through a salt bridge
- compare value between 2 half cells
2
Q
What is a salt bridge?
A
- piece of filter paper soaked in a solution of salt
3
Q
What salt solution is soeaked into the salt bridge? WHat must be considered when choosing the salt bridge?
A
- saturated potassium nitrate
- doesn’t react w/ beaker contents
4
Q
Why is a wire not used?
A
- avoid further metal/ion potentials in the circuit
5
Q
Why is the voltmeter connected high resistance?
A
- ideally infinitely high resist
- avoid any flow of current through circuit
6
Q
Why is current flow avoided?
A
- electrons would flow from most -ve electrode to the positive
- region of high e- to low e-
- voltage measured drops
- to make comparisons, maximum possible volatage must be recorded
- this is emf
7
Q
What does a -ve Eϴ value tell us?
A
- more readily gives up electrons than the SHE
- form ions more readily
- leave more e- behind on the metal,
- making it mre -ve
- eqm lies further to left
- more likely to release electrons than the SHE
