QUANT – Chemistry – Flashcards
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Unlock answers| Ammonium Persulfate- Manganese in Iron |
| Steel has carbon in it therefore it us used to oxidize the carbon to make CO2. Takes Carbon out of steel sample |
| Ascorbic Acid- Manganese In Steel |
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. |
| Potassium Periodate- Manganese in Steel |
| Osidizes manganese ion to the MnO4-. The MnO4- ion is colored (purple) |
| EDTA- Manganese in Steel |
| Standardized use to calculate the molarity of Manganese in manganese nitrate solution. |
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 |
| Calgamite- Manganese in Steel |
| Is a colored indicator when titrating, turns from Red to Blue and purple indicates an almost end point. |
| Nitric Acid - Manganese in Steel |
| Dissolves the steel sample |
| Phosphoric Acid- Manganese in Steel |
| binds up Fe3+ (Iron) so i t wont be used in the reaction with Manganese. So it's not available for oxidation. |
| As the ionic strength (;) increases... |
| the activity, ;, decreases |
| As the effective diameter, ;, decreases.. |
| the activity, ;, becomes more important. |
| Solving Complicated Equilibria, Using systematic Treatment |
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. |
| Charge balance equation |
| where all the positive charges equal the negative ones. |
| Steps to Solving Complidated Equilibria |
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 |
| Ionic Strength |
| is a measure of the total concentration of ions in solution |
| EDTA ( Ethylenediuminetetraacetic Acid) |
- Forms Comlex ions, Metals = electron acceptor EDTA+ electron donor from electrons on Oxygens - pH Dependent ~ 10
|
| Formation/ Stability Constant |
| the equilibrium constant for the reaction of a metal with a ligans (Kf) |
| Endpoint Monitor for EDTA |
| colorimetric indictaor (complexometric indicator)--> where the indicator actually binds to the metal |
| 3 color indicators used with EDTA: |
1.) Calmagite 2.) Eriochrome Black T 3.) Hydrosynapthol Blue |
| Calmagite |
Doesn't work for all metals just for: Zn 2+, Mn 2+, Mg 2+, Ca 2+ Red--> Blue |
| Eriochrome Black T |
Used in limestone Ca 2+ and Mg 2+ Red--> Blue Mg 2+ |
| Hydroxynapthol Blue |
Used at high pH and binds to Ca 2+ Red--> Blue |
| Types of Titrations |
-Direct - Indirect |
| Types of Indirect Titrations |
- Back - Displacement |
| Direct |
| Where the analyte reacts with EDTA if it's at the right pH ( Zn2+, Mn 2+, cA 2+, Mg 2+) |
| Back Titration |
| 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+) |
| When is a Back Titration used? |
- slow rxn - not a good indicator -analyte ppts. w/o EDTA w/ OH- |
| Displacement |
| where the analyte reacts with [Mg EDTA] complex, titrate mg 2+ with EDTA |
When is displacement used?
|
| - when the idicator is bad |
| 2 types of Interference when titrating with EDTA: |
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+ |
| How is blocking of Eriochorm Back T removed? |
| Masking- mask interference by making other metal bound to something else. |
| When masking for Fe 2+ what is used? |
| Cyanide, 6CN- (poison) |
| When masking for Al 3+ what is used? |
| 2N(C2H4OH)2- triethenolamine |
| Transmittance (T) |
| The fraction of the original light that passes through the sample. = P/Po |
| Absorbance |
| The percent transmittance - log(Po/P)--> -log T |
Pathway of measuring the Light Theory |
| Absorbtion (UV or VIS)--> wavelength selector--> Sample-->Detector--> Readout |
Phosphorescence |
| emissions of light transmitted from triplet state to ground state |
| Flouresence |
| emissions of light transmitted from S1 to ground state. (shorter time to reach ground) |
| Factors that influence Absorbance |
1.) Temperature 2.) pH of solution 3.) Solvent system 4.) Electrolyte concentration |
| Ways in which light can deviate from Beer's Law and their corrections: |
- 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 |
| Absorbtion of light source with UV light in a Nova Spec instrument |
| Duterium (D2) lamp |
| Absorbtion of light with VIS light in a Nova Spec instrument |
| Tungston (W) filament |
| Two types of instruments for Spectroscopy |
Singal Beam --> 1 pathway of light 1.) Novaspec 2.) Photodiode Array Instrument |
| Monochromater |
| dispereses light with a grating, in Novaspec |
| Novaspec detector |
| photomultiplier Tube |
| Photodiode Array Instrument |
| wavelength selector is polychromoater- can collect multiple wavelength of light and takes 5 seconds but has not as good of resolution |
| Types of Error in reading Absorbance: |
- 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 |
| Ferrous Ammonium Sulfate 6 hydrate in Limestone |
| Primary standard for standard solutions, did not dry for Fe 3+ determination in limestone analysis. |
| EDTA in Limestone |
| titrant for MgO and CaO was standardized |
| Erio-T indicator in Limestone |
| an alternative for calmagite for titrations of CaO and MgO |
| Hydroxynapthol Blue in Limestone |
| for Calcium titration, because calcium is done at the higher pH. |
| Potassium Cyanide in Limestone |
| Prevents interference to bond to iron and takes it out of the equation for EDTA. |
| pH 10 buffer in Limestone |
| Raises pH when titrating for CaO and MgO with calmagite. |
| Buffer |
| resists changes in pH when acids of bases are added or when dilution occurs |
| Ways to prepare a Buffer: |
- 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+ |
| Amphiprotic |
| can gain H+ or loose H+ |
| 3 M Sulfuric Acid- Limestone |
| used to dissolve primary ammonium sulfate standard |
| Calmagite- Limestone |
| Used to titrate MgO and CaO as and indicator at lower pH. |
| 12M HCL acid- Limestone |
Used to disslove the limestone sample. |
| Hyrdoxylamine hydrochloride 10%- Limestone |
| 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+ |
| 1,10 Phenanthroline 1 %- Limestone |
| Binds with Fe 2+ and forms the bright orange color |
| Sodium Acetitate 1 M- Limestone |
| Used to form a buffer around pH 4 or 5 therefore Iron- phenanthroline can form best around |
| Triethanolamine- Limstone |
| Used to make a complex of mask the aluminum in solution before titrating |
| 6 M KOH- Limestone |
| Adjust the pH to 12 to ppt the Mg so you can titrate Ca alone |
| Oxidation |
| Lose of Electrons |
| Reduction |
| Gain of electrons |
| Ways in which Redox reactions can be measured: |
1.) Electric Charge (q=nxF) 2.) Eelctric Current (I = C/ sec= nF/sec) 3.) Eelectric Potential (E=work (J)/ q(C)) |
| Types of Referance Electrodes: |
-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 |
| 2 types of Electrochemcial Cell |
-Produce Electricity - Use Electricity |
| When a electrochemical cell produces electricty? |
Galvametric Cell ( Spontaneous , E is positive)--> camera and a phone
|
| Whena Electrochimical cell uses electricity? |
| Electrolytic cell ( non spontaneous, e is negative) |
| Galvanic |
| when a electrochemical cell creats a voltage |
Microwave |
| Rotation |
| Infrared |
| Stretching |
| UV and Light |
| Electronic excitation |
| X-rays |
| bond breaking and ionizing |
