Electrochemistry Review and Chromatography

Types of Electrodes

What are the 3 types of electrodes?

1. Standard hydrogen Electrode

2. Silver Chloride Electrode

3. saturated Calomel electrode

What is the E³ of SHE?

1. Standard so we must compare other electrodes to it

2. 0 V

What is the formula for the SHE

2H+ +2e- ——— H2 g

The silver electrode formula?

AgCl (s) + e- ———- Ag (S) +Cl -

What equation do we refer to when calculating Activity of Cl-

E = E not - 0.05916/n loq A(cl-)

What is another name for activity?
In other words how do we treat activity in the nernst equation

Treat it as youre calculating the concentration
It is simply just the effective concentration

Formula for S.C.E?

½ Hg2Cl2 +e - ——— Hg (l) + Cl- (aq)

What are the two types of Indicator Electrode ?

1. Metal Indicator Electrode- Redox

2. Ion selective membrane Electrode— No Redox

Give me examples of Metal indicator electrode?
Think of group 2 elements

Cu, Zn, Hg, Cd

Whatr are the types of inert electrodes ?

Pt, Au, Ag, Pd

Why do we like inert electrodes?

Not selective, stable and fast

How dopes Ion selective membrane work?

It only allows ion of certain interest to pass through through permeation into the membrane

What are two errors in pH measurement?

1. The temperature

2. Acid error

3. Alkaline error
   

What is chromatography?

It is the separation of substances in a mixture.
This is based of the rate at which the components are carried through a stationary phase by a mobile phase

What is the formula for plate height?

Plate Height, H= Variance²/Distance the band travelled

Which is better in terms of efficiency?
A smaller plate height or a larger plate height ?

1. A smaller plate height

2. shows better efficiency

3. shows better separation

What is the formula for plate number?

N = Length of column/ Plate Height

What are the reasons for Band Spreading?

1. Multiple Flow Paths which is A

2. Longitudinal Diffusion is B/Vm

3. Equilibration Time between phases ( Mass transfer) C*Vm

To get the optimal flow rate from the diagram, what do we do?
How do we interpret the diagram?

1. We Look at where all 3 lines intersect which includes the 2 linear lines and the longitudinal diffusion

2. The optimum flow rate also tells us where the minimal plate height will be based on the diagram