Is a mild reducing agent  and is used to keep the manganese in the +2 oxidation state and also is a complexing agent. Complexes Manganese.

pH 10 buffer- Manganese in Steel

We want the experiment at a pH of 10 so EDTA can react (partially ionized), raises the pH to 10

1.) Write equilibrium reaction and their expression

2.) write a charge balance equation

3.) write a mass balance equation--> can't be cretaed or destroyed.

1.) Write reactions and K expressions

2.) write chareg balance

3.) write mass balance

4.) count equations and unknowns

5.) solve for unknowns- assumptions conditions

- Forms Comlex ions,

Metals = electron acceptor

EDTA+ electron donor from electrons on Oxygens

- pH Dependent ~ 10

1.) Calmagite

2.) Eriochrome Black T

3.) Hydrosynapthol Blue

Doesn't work for all metals just for: Zn 2+, Mn 2+, Mg 2+, Ca 2+

Red--> Blue

Used in limestone Ca 2+ and Mg 2+

Red--> Blue   Mg 2+

Used at high pH and binds to Ca 2+

Red--> Blue

-Direct

- Indirect

- Back

- Displacement

- slow rxn

- not a good indicator

-analyte ppts. w/o EDTA w/ OH-

When is displacement used?

1.) When there is another metal present abd both react w/ EDTA therefore do soemthing so only one is present.

2.) Metal binds tightly to indicator--> "metal blocks the indicator"

Metals that block Eriochrome Black T:

FE 3+, Al 3 +, Cr 3+, Co 2+, Ni 2+

Pathway of measuring the Light Theory

Phosphorescence

1.) Temperature

2.) pH of solution

3.) Solvent system

4.) Electrolyte concentration

- Too concentrated of solution  Correction--> dilute sample

- Chemiscal Reaction  Correction--> Choose one w/o chem. rxns

- Instrumental- stray light  Correction--> use middle region or wavelength are

Singal Beam --> 1 pathway of light

1.) Novaspec

2.) Photodiode Array Instrument

- Bubbles in sample reflects and scatters light

-Inconsistant Sample placement, if not b (pathlength) changes

- Fingerprints/ other residue

- Not zeroing, baseline drift

-Light interferance

- Using and incorrect wavelength

-Drift

-Nonhomogenous sample

- Incorrect blank- matrix

- Interferences from other chemical species

- Add a weak acid and it's conjugate base to eachother

- start with a weak acid and add a strong base HA will make A-, HA> OH-

-Start with a weak base and add a strong acid and A- will make HA, A-> H3O+

Used to disslove the limestone sample.

1.) Electric Charge (q=nxF)

2.) Eelctric Current (I = C/ sec= nF/sec)

-Standard Hydrogen electrode- composed of pH wire and H2(g) 1 bar and 1 MHCL

-Saturated Calomel Electrode- (SCE) Uses Hg2 Cl2(S) +electrons

- Silver/ Silver Chloride- Uses AgCl(s) and electrons

Types of Working Electrodes:

Metallic- Pt, Au

Membrane- pH and glass

-Produce Electricity

- Use Electricity

Galvametric Cell ( Spontaneous , E is positive)--> camera and a phone

Microwave