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Chemistry Lab Final Exam
Dr. Hull Chem Lab Final
61
Chemistry
Undergraduate 2
04/23/2011

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Term
Chromatography
Definition
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.
Term
Adsorption
Definition
The attachment of molecules to the surface of a solid
Term
Thin Layer Chromatography (TLC)
Definition
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.
Term
absorption
Definition
implies penetration of melecules into the solid
Term
Applications/ benefits of chromatography
Definition
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
Term
Know how we were able to see the separation of the analgesics even though they are all colorless.
Definition
We put it under a UV light and traced the spots
Term
why do some components travel further than others?
Definition
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
Term
what is an rf value and how do you determine it.
Definition
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)
Term
How is chromatography used to identify substances?
Definition
The composition of the unknown substance (medication) is determined based on matching retention factor (Rf) values and solute spots for the known substances (medications)
Term
In the TLC lab, which active ingredient moved the farthest distance? Why?
Definition
Ibuprofin moved the fartherst b/c it has smaller molecules, has a low affinity and is most soluble
Term
In the TLC lab, which active ingredient moved the shortest distance? Why?
Definition
The 2nd unknown moved the shortest distance (acetaminophen) b/c is has the largest molecules, has a high affinity, and is less soluble
Term
In the TLC lab, what was the purpose of placing a piece of filter paper in the developing chamber?
Definition
To keep the atmosphere within the glass block saturated w/ solvent vapors at all times
Term
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?
Definition
So you have something to compare it to
Term
In the TLC lab, why did you cover the TLC chamber with a watch glass or glass cover?
Definition
So the solvent couldn't evaporate
Term
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)?
Definition
Larger spots will tail and overlap themselves
Term
Can you use TLC to determine if a cup of coffee is caffeinated or not?
Definition
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
Term
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
Definition
Cross contamination of substances
Term
In the TLC lab, what problem might be encountered with the following experimental procedures:

Using a TLC plate which was marked with ink
Definition
The ink would contaminiate the plate and could cause different results
Term
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
Definition
The spots of solution could rub off onto the filter paper
Term
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
Definition
The results would be wrong b/c the spots wouldn't travel up the plate, but instead stay at the bottom
Term

Fe3O----> 3 Fe + 2 O2

 

How would you classify this reaction?

Definition
Decomposition
Term

 AgNO3(aq) + NaCl (aq) ----> NaNO3(aq) + AgCl (s)

 

How would you classify this reaction?

Definition
Double replacement
Term

2 Ag NO3(aq) + Cu(s) ----> Cu (NO3)2(aq) +2 Ag

 

How would you classify this reaction?

Definition
Single replacement
Term

C(s) + O2(g) ----> CO2 (g)

 

How would you classify this reaction?

Definition
Combination
Term
Sodium Chloride
Definition
NaCl
Term
barium nitrate
Definition
Ba(NO3)2
Term
hydrochloric acid
Definition
HCl
Term
sodium hydroxide
Definition
NaOH
Term
sodium carbonate
Definition
Na2CO3
Term
acetic acid
Definition
CH3COOH
Term
barium chloride
Definition
BaCl2
Term
potassium sulfate
Definition
K2SO4
Term
iron(II) sulfate
Definition
FeSO4
Term
potassium hydroxide
Definition
KOH
Term
magnesuim oxide
Definition
MgO
Term
copper(II) sulfate
Definition
CuSO4
Term
iron (III) hydroxide
Definition
Fe(OH)3
Term
potassium nitrate
Definition
KNO3
Term
zinc chloride
Definition
ZnCl2
Term
carbon dioxide
Definition
CO2
Term
iron(III) nitrate
Definition
Fe(NO3)3
Term
silver nitrate
Definition
AgNO3
Term
silver chloride
Definition
AgCl
Term
calcium sulfide
Definition
CaS
Term
How can you determine if a chemical reaction has occurred?
Definition

1. formation of precipitate (change in solubility)

2. evolution of gas

3. change in color

4. change in odor

5. change in temmperature

Term

Determine the product of this reactant:

 

NaCl(aq) + Ba(NO3)2 ----> ?

Definition
NaCl(aq) + Ba(NO3)2 ----> 2NaNO3 + BaCl2
Term

Determine the product of this reactant:

 

HCl(aq) + NaOH(aq) ----> ?

Definition
HCl(aq) + NaOH(aq) ----> NaCl + H2O
Term

Determine the product of this reactant:

 

Na2CO3(aq) + HC2H3O2(aq) ----> ?

Definition
Na2CO3(aq) + HC2H3O2(aq) ----> NaC2H3O2 + H2O + CO2
Term
what factors determine how quickly a reaction occurs?
Definition
concentration and temperature
Term

Determine the product of this reactant:

 

BaCl2(aq) + K2SO4(aq) ----> ?

Definition
BaCl2(aq) + K2SO4(aq) ----> BaSO4 + 2KCl
Term
Base
Definition
Increases OH- concentration in solution (8-14)
Term

Determine the product of this reactant:

 

CuSO4(aq) + NH4OH(aq) ----> ?

Definition
CuSO4(aq) + NH4OH(aq) ----> Cu(OH)2 + (NH4)2SO4
Term
What are the 4 different product formations?
Definition

1. precipitation

2. neutralization (A/B)

3. Redox

4. Gas-forming

Term
Kinetics
Definition
The study of how fast or slow a reaction occurs
Term
Acid
Definition
Increases H+ concentration in solution
(0-6)
Term
What must take place in order for a chemical reaction to occur?
Definition
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
Term
Know what color litmus paper turns in the presence of an acid and a base.
Definition
Acid: Red
Base: Blue
Term
Is HCl and acid or a base?
Definition
Acid
Term
Is NaOH an acid or a base?
Definition
Base
Term
What is phenolphthalein and what color does it turn when it is in an acid and a base?
Definition
Indicator

Color in acid:clear
Color in base: pink
Term
Give some examples of acids and bases
Definition
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
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