Chemistry Lab Final Exam – Flashcards
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| Chromatography |
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| Chromatography is a versatile physical method separation and characterization by which two or more components in a mixture are distributed between two phases: stationary and moble. |
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| Adsorption |
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| The attachment of molecules to the surface of a solid |
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| Thin Layer Chromatography (TLC) |
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| is a specialized form of chromatography. It is a simple, sensitive and quick technique for analyzing and separating ultra small quantities of organic compounds. It is used specifically to check the purity of a compound, to determine the number of components in a mixture, to evaluate the progess of a chemical reaction, and to analyze the composition of a mixture. |
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| absorption |
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| implies penetration of melecules into the solid |
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| Applications/ benefits of chromatography |
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| evaluating air quality determining pesticide residues on fruits and vegetables monitoring respiratory gases during anesthesia searching for organic compounds on other planets determining metabolic pathways and mechanisms of action of drugs detecting and solving crimes |
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| Know how we were able to see the separation of the analgesics even though they are all colorless. |
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| We put it under a UV light and traced the spots |
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| why do some components travel further than others? |
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| Small molecules more faster than large molecules. The more soluble the solution, the fater it is carried up, the less soluble it is makes it stay and the liquid will pass right through |
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| what is an rf value and how do you determine it. |
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| The distance traveled by each component is expressed as a rate or retention factor (Rf) Rf= distance traveled by an ingredient/ distance traveled by the solvent (measured from origin point where the spot was initially applied to the plate) |
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| How is chromatography used to identify substances? |
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| The composition of the unknown substance (medication) is determined based on matching retention factor (Rf) values and solute spots for the known substances (medications) |
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| In the TLC lab, which active ingredient moved the farthest distance? Why? |
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| Ibuprofin moved the fartherst b/c it has smaller molecules, has a low affinity and is most soluble |
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| In the TLC lab, which active ingredient moved the shortest distance? Why? |
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| The 2nd unknown moved the shortest distance (acetaminophen) b/c is has the largest molecules, has a high affinity, and is less soluble |
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| In the TLC lab, what was the purpose of placing a piece of filter paper in the developing chamber? |
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| To keep the atmosphere within the glass block saturated w/ solvent vapors at all times |
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| In the TLC lab, in order to identify an unknown analgesic using TLC, a sample of a known analgesic (a standard) must be spotted on the same plate as the unknown. Why is this necessary? |
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| So you have something to compare it to |
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| In the TLC lab, why did you cover the TLC chamber with a watch glass or glass cover? |
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| So the solvent couldn't evaporate |
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| In the TLC lab, why is it important that the spots on the TLC plate be made as small as possible (less than 2 mm in diameter)? |
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| Larger spots will tail and overlap themselves |
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| Can you use TLC to determine if a cup of coffee is caffeinated or not? |
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| Yes, if you saturate a spot w/ caffeine and saturate another spot w/ the coffee, you could see the similarities of each and compare their movement up the TLC plate |
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| In the TLC lab, what problem might be encountered with the following experimental procedures: A single micropipet was used to stop four analgesic samples of a TLC plate |
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| Cross contamination of substances |
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| In the TLC lab, what problem might be encountered with the following experimental procedures: Using a TLC plate which was marked with ink |
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| The ink would contaminiate the plate and could cause different results |
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| In the TLC lab, what problem might be encountered with the following experimental procedures: A TLC plate touching the filter paper liner of the development chamber |
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| The spots of solution could rub off onto the filter paper |
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| In the TLC lab, what problem might be encountered with the following experimental procedures: The depth of the solvent is above the levol of the spots |
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| The results would be wrong b/c the spots wouldn't travel up the plate, but instead stay at the bottom |
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Fe3O4 ----> 3 Fe + 2 O2
How would you classify this reaction? |
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| Decomposition |
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AgNO3(aq) + NaCl (aq) ----> NaNO3(aq) + AgCl (s)
How would you classify this reaction? |
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| Double replacement |
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2 Ag NO3(aq) + Cu(s) ----> Cu (NO3)2(aq) +2 Ag
How would you classify this reaction? |
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| Single replacement |
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C(s) + O2(g) ----> CO2 (g)
How would you classify this reaction? |
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| Combination |
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| Sodium Chloride |
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| NaCl |
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| barium nitrate |
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| Ba(NO3)2 |
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| hydrochloric acid |
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| HCl |
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| sodium hydroxide |
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| NaOH |
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| sodium carbonate |
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| Na2CO3 |
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| acetic acid |
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| CH3COOH |
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| barium chloride |
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| BaCl2 |
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| potassium sulfate |
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| K2SO4 |
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| iron(II) sulfate |
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| FeSO4 |
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| potassium hydroxide |
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| KOH |
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| magnesuim oxide |
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| MgO |
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| copper(II) sulfate |
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| CuSO4 |
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| iron (III) hydroxide |
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| Fe(OH)3 |
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| potassium nitrate |
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| KNO3 |
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| zinc chloride |
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| ZnCl2 |
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| carbon dioxide |
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| CO2 |
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| iron(III) nitrate |
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| Fe(NO3)3 |
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| silver nitrate |
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| AgNO3 |
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| silver chloride |
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| AgCl |
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| calcium sulfide |
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| CaS |
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| How can you determine if a chemical reaction has occurred? |
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1. formation of precipitate (change in solubility) 2. evolution of gas 3. change in color 4. change in odor 5. change in temmperature |
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Determine the product of this reactant:
NaCl(aq) + Ba(NO3)2 ----> ? |
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| NaCl(aq) + Ba(NO3)2 ----> 2NaNO3 + BaCl2 |
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Determine the product of this reactant:
HCl(aq) + NaOH(aq) ----> ? |
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| HCl(aq) + NaOH(aq) ----> NaCl + H2O |
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Determine the product of this reactant:
Na2CO3(aq) + HC2H3O2(aq) ----> ? |
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| Na2CO3(aq) + HC2H3O2(aq) ----> NaC2H3O2 + H2O + CO2 |
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| what factors determine how quickly a reaction occurs? |
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| concentration and temperature |
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Determine the product of this reactant:
BaCl2(aq) + K2SO4(aq) ----> ? |
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| BaCl2(aq) + K2SO4(aq) ----> BaSO4 + 2KCl |
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| Base |
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| Increases OH- concentration in solution (8-14) |
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Determine the product of this reactant:
CuSO4(aq) + NH4OH(aq) ----> ? |
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| CuSO4(aq) + NH4OH(aq) ----> Cu(OH)2 + (NH4)2SO4 |
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| What are the 4 different product formations? |
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1. precipitation 2. neutralization (A/B) 3. Redox 4. Gas-forming |
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| Kinetics |
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| The study of how fast or slow a reaction occurs |
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| Acid |
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| Increases H+ concentration in solution (0-6) |
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| What must take place in order for a chemical reaction to occur? |
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| Reactants must collide effectively and then combine to form new cubstances. Consequently, the greater the number of particles (the higher the concentration) and the higher the temperature (the more rapid and more energetic the motion of the particles), the faster the reaction |
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| Know what color litmus paper turns in the presence of an acid and a base. |
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| Acid: Red Base: Blue |
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| Is HCl and acid or a base? |
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| Acid |
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| Is NaOH an acid or a base? |
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| Base |
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| What is phenolphthalein and what color does it turn when it is in an acid and a base? |
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| Indicator Color in acid:clear Color in base: pink |
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| Give some examples of acids and bases |
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| Acids:Lemon juice, pineapple juice, tomato juice, grapefruit juice, clorox-2, vinegar, lysol, sugar, soda pop Bases: Liquid drano, baking powder, baking soda, bleach, ammonia, milk of magnesia, nair |
