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QUANT
Exam 2
77
Chemistry
Not Applicable
03/08/2008

Additional Chemistry Flashcards

 


 

Cards

Term
Ammonium Persulfate- Manganese in Iron
Definition
Steel has carbon in it therefore it us used to oxidize the carbon to make CO2. Takes Carbon out of steel sample
Term
Ascorbic Acid- Manganese In Steel
Definition

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.

Term
Potassium Periodate- Manganese in Steel
Definition
Osidizes manganese ion to the MnO4-. The MnO4- ion is colored (purple)
Term
EDTA- Manganese in Steel
Definition
Standardized use to calculate the molarity of Manganese in manganese nitrate solution.
Term

pH 10 buffer- Manganese in Steel

Definition

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

Term
Calgamite- Manganese in Steel
Definition
Is a colored indicator when titrating, turns from Red to Blue and purple indicates an almost end point.
Term
Nitric Acid - Manganese in Steel
Definition
Dissolves the steel sample
Term
Phosphoric Acid- Manganese in Steel
Definition
binds up Fe3+ (Iron) so i t wont be used in the reaction with Manganese. So it's not available for oxidation.
Term
As the ionic strength (μ) increases...
Definition
the activity, Ψ, decreases
Term
As the effective diameter, ←, decreases..
Definition
the activity, Ψ, becomes more important.
Term
Solving Complicated Equilibria, Using systematic Treatment
Definition

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.

Term
Charge balance equation
Definition
where all the positive charges equal the negative ones.
Term
Steps to Solving Complidated Equilibria
Definition

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

Term
Ionic Strength
Definition
is a measure of the total concentration of ions in solution
Term
EDTA ( Ethylenediuminetetraacetic Acid)
Definition

- Forms Comlex ions,

Metals = electron acceptor

EDTA+ electron donor from electrons on Oxygens

- pH Dependent ~ 10

 

Term
Formation/ Stability Constant
Definition
the equilibrium constant for the reaction of a metal with a ligans (Kf)
Term
Endpoint Monitor for EDTA
Definition
colorimetric indictaor (complexometric indicator)--> where the indicator actually binds to the metal
Term
3 color indicators used with EDTA:
Definition

1.) Calmagite

2.) Eriochrome Black T

3.) Hydrosynapthol Blue

Term
Calmagite
Definition

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

Red--> Blue

Term
Eriochrome Black T
Definition

Used in limestone Ca 2+ and Mg 2+

Red--> Blue   Mg 2+

Term
Hydroxynapthol Blue
Definition

Used at high pH and binds to Ca 2+

Red--> Blue

Term
Types of Titrations
Definition

-Direct

- Indirect

Term
Types of Indirect Titrations
Definition

- Back

- Displacement

Term
Direct
Definition
Where the analyte reacts with EDTA if it's at the right pH ( Zn2+, Mn 2+, cA 2+, Mg 2+)
Term
Back Titration
Definition
Where you react metal (analyte) with excess EDTA in the flask. Put mpre EDTA in than what was needed. Titrate EDTA that is left with a standard metal solution (Zn 2+)
Term
When is a Back Titration used?
Definition

- slow rxn

- not a good indicator

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

Term
Displacement
Definition
where the analyte reacts with [Mg EDTA] complex, titrate mg 2+ with EDTA
Term

When is displacement used?

 

Definition
- when the idicator is bad
Term
2 types of Interference when titrating with EDTA:
Definition

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"

Term

Metals that block Eriochrome Black T:

Definition

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

Term
How is blocking of Eriochorm Back T removed?
Definition
Masking- mask interference by making other metal bound to something else.
Term
When masking for Fe 2+ what is used?
Definition
Cyanide, 6CN- (poison)
Term
When masking for Al 3+ what is used?
Definition
2N(C2H4OH)2- triethenolamine
Term
Transmittance (T)
Definition
The fraction of the original light that passes through the sample. = P/Po
Term
Absorbance
Definition
The percent transmittance - log(Po/P)--> -log T
Term

Pathway of measuring the Light Theory

Definition
Absorbtion (UV or VIS)--> wavelength selector--> Sample-->Detector--> Readout
Term

Phosphorescence

Definition
emissions of light transmitted from triplet state to ground state
Term
Flouresence
Definition
emissions of light transmitted from S1 to ground state. (shorter time to reach ground)
Term
Factors that influence Absorbance
Definition

1.) Temperature

2.) pH of solution

3.) Solvent system

4.) Electrolyte concentration

Term
Ways in which light can deviate from Beer's Law and their corrections:
Definition

- 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

Term
Absorbtion of light source with UV light in a Nova Spec instrument
Definition
Duterium (D2) lamp
Term
Absorbtion of light with VIS light in a Nova Spec instrument
Definition
Tungston (W) filament
Term
Two types of instruments for Spectroscopy
Definition

Singal Beam --> 1 pathway of light

1.) Novaspec

2.) Photodiode Array Instrument

Term
Monochromater
Definition
dispereses light with a grating, in Novaspec
Term
Novaspec detector
Definition
photomultiplier Tube
Term
Photodiode Array Instrument
Definition
wavelength selector is polychromoater- can collect multiple wavelength of light and takes 5 seconds but has not as good of resolution
Term
Types of Error in reading Absorbance:
Definition

- 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

Term
Ferrous Ammonium Sulfate 6 hydrate in Limestone
Definition
Primary standard for standard solutions, did not dry for Fe 3+ determination in limestone analysis.
Term
EDTA in Limestone
Definition
titrant for MgO and CaO was standardized
Term
Erio-T indicator in Limestone
Definition
an alternative for calmagite for titrations of CaO and MgO
Term
Hydroxynapthol Blue in Limestone
Definition
for Calcium titration, because calcium is done at the higher pH.
Term
Potassium Cyanide in Limestone
Definition
Prevents interference to bond to iron and takes it out of the equation for EDTA.
Term
pH 10 buffer in Limestone
Definition
Raises pH when titrating for CaO and MgO with calmagite.
Term
Buffer
Definition
resists changes in pH when acids of bases are added or when dilution occurs
Term
Ways to prepare a Buffer:
Definition

- 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+

Term
Amphiprotic
Definition
can gain H+ or loose H+
Term
3 M Sulfuric Acid- Limestone
Definition
 used to dissolve primary ammonium sulfate standard
Term
Calmagite- Limestone
Definition
Used to titrate MgO and CaO as and indicator at lower pH.
Term
12M HCL acid- Limestone
Definition

Used to disslove the limestone sample.

Term
Hyrdoxylamine hydrochloride 10%- Limestone
Definition
Used to convert Fe3+ to Fe 2+ and reduce Copper to Copper I and also prevents the indicator from being oxidized. Fe 3+ absorbs at a different wavelength than Fe2+
Term
1,10 Phenanthroline 1 %- Limestone
Definition
Binds with Fe 2+ and forms the bright orange color
Term
Sodium Acetitate 1 M- Limestone
Definition
Used to form a buffer around pH 4 or 5 therefore Iron- phenanthroline can form best around
Term
Triethanolamine- Limstone
Definition
Used to make a complex of mask the aluminum in solution before titrating
Term
6 M KOH- Limestone
Definition
Adjust the pH to 12 to ppt the Mg so you can titrate Ca alone
Term
Oxidation
Definition
Lose of Electrons
Term
Reduction
Definition
Gain of electrons
Term
Ways in which Redox reactions can be measured:
Definition

1.) Electric Charge (q=nxF)

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

3.) Eelectric Potential (E=work (J)/ q(C))
Term
Types of Referance Electrodes:
Definition

-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

Term

Types of Working Electrodes:

Definition

Metallic- Pt, Au

Membrane- pH and glass

Term
2 types of Electrochemcial Cell
Definition

-Produce Electricity

- Use Electricity

Term
When a electrochemical cell produces electricty?
Definition

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

 

Term
Whena Electrochimical cell uses electricity?
Definition
Electrolytic cell ( non spontaneous, e is negative)
Term
Galvanic
Definition
when a electrochemical cell creats a voltage
Term

Microwave

Definition
Rotation
Term
Infrared
Definition
Stretching
Term
UV and Light
Definition
Electronic excitation
Term
X-rays
Definition
bond breaking and ionizing
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