Redox and Electrode Potential Flashcards
What does the oxidation agents do
They accept electrons (they are reduced in reaction )
What does the reducing agent do in the reaction
It donates electrons (they are oxidised)
True or false
Different substances are more or less efficient at reducing/ oxidising?
True different substances are better or worse at being oxidising or reducing agent
Separate this redox equation into its two half equations
CuSO4 + Zn —> ZnSO4 + Cu
Blue. + grey —> colourless + brown
Remove spectator ions
Cu2+ + Zn —> Cu + Zn2+
Create the two half equations
Cu2+ + 2e- —> Cu
Zn —> Zn2+ + 2e-
When can the reducing be the oxidising agent and vice Versa
1) the reducing agent has a form which could oxidise something
2) every oxidising agent has a form which could reduce something
They just wouldn’t be as good at this
What does the electrode potential allow us to do
Electrode potential allows us to quantify how good an oxidising or reducing agent a species is
(The scale is based on the tendency for the oxidising form of a redox pair to enquire electrons thus becoming reduced)
If there is a more positive electrode potential what does that mean
The more positive the value the more likely they are to acquire electrons
(Better oxidising agents)
If the potential differences is negatives then…
Electrons tend to be produced and the reaction is moving from the RHS to the LHS
(Negative voltage means more electrons being thrown out )
If the potential difference is positive then electrons tend to….
Electrons tend to be absorbed and the reaction is moving from the LHS to the RHS
What is the standard electrode potential a measure of
Standard electrode potential - a measurement of the potential difference between an electrode and the solution in a half cell relative to the standard hydrogen electrode
What conditions are considered standard for standard electrode potential
1 mol dm-3 solution
298 K (25oc)
10^5 Pa (for gaseous)
How do we measure electrode potential
It cannot be measured directly so is measured next to another half cell.
Def of half cell
An electrode in contact with a solution of its own ions forming part of a cell
E.g Zn metal dipped in ZnSO4 solution
When measure a porous partition is needed
+ what is this called
+ what is it for
Porous partition can be as simple as a salt bridge - solution of KCl soaked into filtered paper
It allows for electrical connection of 2 half cells by virtue of free ions provided by KCl
Which way is the electromotive force taken
The electromotive force of the cell is taken by convention to act from L —> R through the cell
This means
E cell = E RSH electrode — E LHS electrode
