Ochem Lab Final Exam Review
In the Aspirin lab, which one is the limiting reagent/reactant? a. salicylic acid b. acetic anhydride
salicylic acid
In the esterification lab, After extracting you will need to dry the reaction mixture. What will you use to dry it with? a. sodium hydroxide b. sodium chloride c. sodium sulfate d. sodium bicarbonate
sodium sulfate
In the Acetaminophen lab, the solvent is a. water b. acetic anhydride c. p-aminophenol
water
In the esterification lab, Let's assume that you have 0.001 moles of Amberlyst-15 at the start of your reaction? Roughly how much Amberlyst-15 will you have at the end of the reaction?
0.001 moles
Suppose, the mass of the pentyl acetate (product ester) is 1.71 g. Calculate the number of moles of the product ester. Molar mass of pentyl acetate = 130.19 g/mol
0.013 moles
Suppose, the mass of your starting 1-pentanol is 1.61 g. Calculate the number of moles of 1-pentanol. Molar mass of 1-pentanol = 88.15 g/mol
0.018 moles
Suppose, the mass of your starting acetic acid is 3.15 g. Calculate the number of moles of acetic acid. Molar mass of acetic acid = 60.052 g/mol
0.052 moles
In the TLC lab, the mobile phase for the experiment is
0.5% acetic acid in ethyl acetate
How many peaks in an IR spectrum would you expect to see that would characterize an alcohol functional group? a. 1 b. 2 c. 3 d. 4
1
When taking the IR spectrum of a liquid sample, how many drop(s) of liquid should you use? a. 1 b. 2 c. 3
1
In the esterification lab, which is the limiting reactant a. 1-pentanol b. acetic acid
1-pentanol
Suppose, the mass of the crude aspirin product obtained is 182 mg. Calculate the number of moles of crude product obtained. Molar mass of aspirin = 180.158 g/mol
1.01 * 10^-3 moles
In the melting/boiling point lab, What is the Melting Range (in C) of the pure Unknown mixed with Salicylic Acid?
115.5
The IR spectrum of a liquid sample of cyclohexanone is shown above. 2800 - 3000 cm^-1: 1710 cm^-1:
2800 - 3000 cm^-1: Csp3-H 1710 cm^-1: C=O (ketone)
The IR spectrum of a liquid sample of hexyl acetate is shown above. 2850 - 2980 cm^-1: 1742 cm^-1:
2850 - 2980 cm^-1: Csp3-H 1742 cm^-1: C=O (ester)
The IR spectrum of a liquid sample of hexanal is shown above. 2900 - 3000 cm^-1: 2716 - 2817 cm^-1: 1720 cm^-1:
2900 - 3000 cm^-1: Csp3-H 2716 - 2817 cm^-1: C-H (aldehyde) 1720 cm^-1: C=O (aldehyde)
Suppose, the volume of acetic anhydride used is 0.3 mL. How many moles of acetic anhydride is this? Density of acetic anhydride = 1.08 g/mL Molar mass of acetic anhydride = 102.1 g/mol
3.17 * 10^-3 moles
The IR spectrum of a liquid sample of cyclohexene is shown above. 3050 cm^-1: 2800 - 2950 cm^-1: 1650 cm^-1
3050 cm^-1: Csp2-H 2800 - 2950 cm^-1: Csp3-H 1650 cm^-1: C=C (alkene)
The IR spectrum of a solid sample of benzoic acid is shown above. 3200 cm^-1: 3100 cm^-1: 1700 cm^-1: 1590 cm^-1:
3200 cm^-1: O-H (carboxylic acid) 3100 cm^-1: Csp2-H 1700 cm^-1: C=O (carboxylic acid) 1590 cm^-1: Benzene ring
The IR spectrum of a solid sample of 4-t-butyl phenol is shown above. 3250 cm^-1: 3100 cm^-1: 2950 cm^-1: 1600 cm^-1:
3250 cm^-1: O-H (alcohol) 3100 cm^-1: Csp2-H 2950 cm^-1: Csp3-H 1600 cm^-1: Benzene Ring
The IR spectrum of a liquid sample of hexanol is shown above. 3350 cm^-1: 2800 - 3000 cm^-1:
3350 cm^-1: O-H (alcohol) 2800 - 3000 cm^-1: Csp3-H
The IR spectrum of a liquid sample of cyclohexyl amine is shown above. 3400 cm^-1: 3300 cm^-1: 2800 - 2950 cm^-1:
3400 cm^-1: N-H (primary amine) 3300 cm^-1: N-H (primary amine) 2800 - 2950 cm^-1: Csp3-H
The IR spectrum of a liquid sample of aniline is shown above. 3500 cm^-1: 3400 cm^-1: 3000 cm^-1: 1510 cm^-1:
3500 cm^-1: N-H (primary amine) 3400 cm^-1: N-H (primary amine) 3000 cm^-1: Csp2-H 1510 cm^-1: benzene ring
In the Aspirin lab, What should be the temperature of the water bath when you are refluxing your reaction? a. 120-140 C b. 45-55 C c. 100-120 C d. 60-80 C
45-55 C
Suppose, the mass of the pure aspirin product obtained is 93 mg. Calculate the number of moles of pure product obtained. Molar mass of aspirin = 180.158 g/mol
5.16 * 10^-4 moles
Suppose, the volume of acetic anhydride used is 0.5 mL. Calculate the number of moles of acetic anhydride used. Density of acetic anhydride = 1.08 g/mL Molar mass of acetic anhydride = 102.1 g/mol
5.3 * 10^-3 moles
Suppose, the mass of the pure acetaminophen is 90 mg. Calculate the number of moles of the pure product obtained. Molar mass of acetaminophen = 151.2 g/mol
5.95 * 10^-4 moles
Suppose, the mass of crude acetaminophen obtained is 128 mg. Calculate the number of moles of crude product obtained. Molar mass of acetaminophen = 151.2 g/mol
8.46 * 10^-4 moles
What is the purpose of refluxing your reaction? a. To heat the reaction b. Add thermal energy c. Help to break bonds d. A,B, and C
A,B, and C
Molecules that move from solution to the solid are said to be in the process of ___________ Molecules that move from the solid into solution are said to be in the process of __________
Absorbing Desorbing
Consider the experiment you performed using your second TLC plate. You had to run the second TLC experiment involving four different spots (acetylsalicylic acid, acetaminophen, caffeine and Tylenol tablet extract) The purpose of this experiment was the preliminary identification of known chemicals in Tylenol tablet using TLC. Based on your observations, what did you decide might be the chemicals present in Tylenol. a. Acetylsalicylic acid b. Acetaminophen c. Caffeine
Acetaminophen
Consider the experiment you performed using your first TLC plate. You had to run the first TLC experiment involving four different spots (acetylsalicylic acid, acetaminophen, caffeine and Anacin tablet extract) The purpose of this experiment was the preliminary identification of known chemicals in Anacin tablet using TLC. Based on your observations, what did you decide might be the chemicals present in Anacin. a. Acetylsalicylic acid only b. Acetaminophen only c. Acetylsalicylic acid and Caffeine
Acetylsalicylic acid and Caffeine
In the esterification lab, What is the name of the catalyst in this reaction? a. Amberlyst 15 b. Amberlyst 16 c. sulfuric acid d. glacial acetic acid
Amberlyst 15
In the esterification lab, During extraction, the organic layer is on the top and the aqueous layer is at the bottom. Which is more dense, the organic layer or the aqueous layer?
Aqueous layer
Select the correct answer for why most reactions have an activation energy and have to be heated. a. Because new bonds have to be made before old bonds can be broken. b. Because old bonds have to be broken before new bonds can be made.
Because old bonds have to be broken before new bonds can be made.
When placing the TLC plates in the developing chamber, where should the solvent line be with respect to the samples that are spotted on the TLC plate. a. Above the line where the samples are spotted on the TLC plate b. Below the line where the samples are spotted on the TLC plate c. On the line where the samples are spotted on the TLC plate
Below the line where the samples are spotted on the TLC plate
The IR spectrum of the pure acetaminophen is shown above in question 10. Identify the peak at 1608 cm^-1.
Benzene ring
the IR spectrum of a solid sample that was taken by a student. Which of the following is/are possible causes for the weak signals observed. a. Crystals were not ground finely enough b. Not enough pressure on the sample on top of the diamond crystal c. Baseline was not run correctly d. Diamond crystal is not clean e. Both A and B are possible f. Both C and D are possible
Both A and B are possible
The IR spectrum of the pure acetaminophen is shown above in question 10. Identify the peak at 1649 cm^-1.
C=O (amide)
In the Biodiesel lab, Carbonic acid is unstable in water and will spontaneously decompose into _____ and ____ a. Carbon monoxide and water b. Carbon dioxide and water c. Acetic acid and water
Carbon dioxide and water
Very often organic solutions are washed with brine, which is a concentrated solution of sodium chloride (salt) in water. If a solution of carbon tetrachloride as the organic solvent is washed with brine and the organic and aqueous solutions allowed to settle, which will be the bottom layer? The density of carbon tetrachloride is 1.59 g/cm-3 and the density of brine is 1.15 g/cm-3. a. Brine b. Carbon tetrachloride (CCL4)
Carbon tetrachloride (CCL4)
The IR spectrum of a liquid sample of cyclohexane is shown above. 2800 - 2950 cm^-1:
Csp3-H
A student wants to run an IR spectrum of a sample. The student knows that the sample is an aromatic ketone, but gets the spectrum shown below, which is not of an aromatic ketone and not what they expected. The student was in a hurry and forgot to do something important when running the spectrum. Based on the functional group you see in the spectrum, what did they forget to do? a. Crystals were not ground finely enough b. Didn't let the isopropanol dry
Didn't let the isopropanol dry
Acetone is H-bond donor or H-bond acceptor
H-bond acceptor
Acetophenone is H-bond donor or H-bond acceptor
H-bond acceptor
Ammonia is H-bond donor or H-bond acceptor
H-bond donor
Benzoic acid is H-bond donor or H-bond acceptor
H-bond donor and H-bond acceptor
Ethanol has a higher boiling point than dimethyl ether. Which intermolecular force is primarily responsible for this difference? a. Dipole-Dipole Forces b. Hydrogen bonding c. Ion-Dipole Forces d. Induced Dipole (London Dispersion Forces)
Hydrogen bonding
How many C=C double bond(s) does the following unsaturated fatty acids in Canola oil have? I: trans-oleic acid II: cis-oleic acid III: linoleic acid a. I: 0, II: 0, III: 0 b. I: 0, II: 1, III: 1 c. I: 1, II: 1, III: 1 d. I: 1, II: 1, III: 2 e. I: 2, II: 2, III: 1
I: 1, II: 1, III: 2
What does the 'inter' part of the word mean in the term intermolecular forces? a. INTER means BETWEEN two separate molecules b. INTER means WITHIN one particular molecule
INTER means BETWEEN two separate molecules
In the esterification lab, What technique will you use to characterize the product? a. Melting point b. boiling point c. NMR d. IR
IR
The sodium sulfate is added at the end of the procedure as a drying agent. Which is/are the most important intermolecular forces between the sodium sulfate and the water? a. Dipole-Dipole Forces b. Ion-Dipole Forces c. Hydrogen bonding d. Induced Dipole (London Dispersion Forces) e. Hydrophobic interactions
Ion-Dipole Forces and Hydrogen bonding
In the Acetaminophen lab, Select TWO methods that you will use in this lab to characterize your product. a. IR spectroscopy b. TLC c. boiling point d. melting point
Ir spectroscopy and melting point
Why is energy released when IMFs form between molecules as they approach each other? a. Making IMFs lowers the energy of electrons b. Making IMFs raises the energy of electrons c. Making IMFs have got nothing to do with the energy of electrons!
Making IMFs lowers the energy of electrons
The IR spectrum of the pure acetaminophen product is shown above. Identify the peak at 3321 cm^-1.
N-H (amide)
In the Biodiesel lab, What is the purpose of adding acetic acid (vinegar) to the reaction flask after the reaction is complete? a. Used as a drying agent b. Neutralize the acid before extraction c. Neutralize the base before extraction
Neutralize the base before extraction
The IR spectrum of the pure acetaminophen is shown above in question 10. Identify the peak at 3125 cm^-1.
O-H (alcohol)
Benzaldehyde is Polar Protic or Polar Aprotic. Benzaldehyde is H-bond donor or H-bond acceptor or both
Polar Aprotic H-bond acceptor
Benzonitrile is Polar Protic or Polar Aprotic. Benzonitrile is H-bond donor or H-bond acceptor or both
Polar Aprotic H-bond acceptor
Benzophenone is Polar Protic or Polar Aprotic. Benzophenone is H-bond donor or H-bond acceptor or both
Polar Aprotic H-bond acceptor
In the TLC lab, the stationary phase for the experiment is
Silica
Suppose, the IR spectrum of your purified ester product shows the presence of an O-H peak. What will be your interpretation of this observation? a. Some water (H-O-H) by-product still present b. Some unreacted starting alcohol still present c. Some unreacted starting acetic acid still present d. Some amberlyst-15 catalyst still present
Some unreacted starting alcohol still present
In the TLC lab, Which technique in this experiment will you use to determine the purity of the unknown sample? a. TLC b. melting point c. IR d. NMR
TLC
In the esterification lab, Why can't you isolate the product in your reaction by crystallization. a. The product is a solid b. the product is a liquid
The product is a liquid
True or False? Faster moving molecules (large Rf) have a weaker IMF with the solid stationary phase and a stronger IMF with the solvent.
True
True or False? Formation of side products reduce the chemical yield of a reaction but formation of by-products don't.
True
True or False? The solution is cooled in an ice bath when crystallizing because the solubility constant decreases with decreasing temperature which will result in more precipitation.
True
True or False? You will use recrystallization to purify your reaction product.
True
True or false? The purpose of refluxing this reaction is to maintain a constant temperature.
True
True/False Biodiesel is said to be "carbon neutral" that is it neither adds to or subtracts from the amount of carbon dioxide in the atmosphere
True
True/False The Le Chatelier principle says that equilibrium will respond to external changes in order to re-establish equilibrium. In this experiment you will perturb an equilibrium, push it to the side of the products by using a high concentration of one of the reactants.
True
True/False We need to run the product through the pipette that contains sodium sulfate to remove the last traces of water
True
You can damage the pipette by dropping it on the floor. a. True b. False
True
You can damage the pipette by turning the dial to greater than 1000. a. True b. False
True
In the solubility lab, Based on your experiments on miscibility, which of the following solvent-solvent combination is immiscible? a. Water-diethyl ether b. acetone-diethyl ether c. water-acetone
Water-Diethyl ether
How are you going to see (visualize) the spots on the TLC plates? a. You can see them with your naked eyes. b. You can see them with a flashlight. c. You can see them in the dark. d. You can see them with a UV lamp.
You can see them with a UV lamp.
What vibrations do the peaks observed in an infrared spectrum with frequencies > 1500 cm-1 correspond to? a. a specific functional group b. a specific bond c. a specific molecule
a specific bond
When assigning a peak in an infrared spectrum, what should you assign it to? a. a specific functional group b. a molecule c. a specific bond and a functional group it is part of
a specific bond and a functional group it is part of
In the Acetaminophen lab, the reagent is a. water b. acetic anhydride c. p-aminophenol
acetic anhydride
After extraction of the benzoic acid into the aqueous solution as its anionic salt, the ether solution was then washed with water two further times. What do you think was the purpose of these two wash steps? a. To remove any remaining sodium hydroxide from the ether b. To remove any remaining benzoic acid salt from the ether c. To remove any remaining polar impurities from the ether d. all of the above
all of the above
Extraction will be performed using sodium bicarbonate (NaHCO3), which is a weaker base than sodium hydroxide (NaOH). Why is it better to use the weaker base here? a. The ester will react with the stronger base b. Using NaHCO3 helps extraction by liberating CO2 c. Using NaHCO3 makes the reaction involved in extraction irreversible d. all of the above
all of the above
What is the role of the Amberlyst-15 catalyst? a. To speed up the reaction b. To lower the activation energy barrier c. To enable the reactants to overcome the activation energy barrier d. all of the above
all of the above
What kind of artifacts does the background scan remove from the IR spectrum? a. IR absorptions due to atmospheric water b. IR absorptions due to atmospheric carbon dioxide c. instrument artifacts d. all of the above
all of the above
Which of the following dynamical processes contribute to the Rf values in your TLC experiments? a. Rate of adsorption to the stationary phase b. Rate of desorption (solvation) c. Rate of solvent (mobile phase) motion d. all of the above
all of the above
Which of the following is a part of your PPE for lab every week? a. long pants b. closed-toed shoes c. lab coar d. goggles e. gloves f. all of the above are required each week!
all of the above are required each week
What must you do to the solid sample AFTER they have been placed on the IR spectrometer? a. apply pressure to it b. blow on it c. air it out d. apply liquid to it
apply pressure to it
Why does the water go into the bottom of a water condenser and not the top? a. So that the water fills the condenser b. So that the cold part is at the bottom c. both A and B are correct d. Actually, water should go in to the top, not the bottom
both A and B are correct
In the Acetaminophen lab, acetic acid is the a. desired product b. side product c. by product
by product
What is the name of the products that are unavoidably formed the same time as your desired product? a. side products b. unwanted products c. unknown products d. by-products
by-products
In the Biodiesel lab, the reagent is a. canola oil and methanol b. canola oil and ethanol c. vegetable oil and methanol d. vegetable oil and ethanol
canola oil and methanol
What must you do to a solid sample BEFORE you take the IR spectrum of the solid sample? a. dissolve it with water b. pack it into a pile c. crush it d. make it a paste
crush it
In the Aspirin lab, What method will you use to isolate the product in your reaction in this synthesis? a. extraction b. crystallization c. distillation
crystallization
In the Acetaminophen lab, What TWO steps will be used first to isolate the product of the reaction? a. dehydration and filtration b. crystallization and filtration c. crystallization and distillation d. distillation and filtration
crystallization and filtration
In the structure of hexanol in question 19, which type of line represents an O-H hydrogen bond? a. dashed line b. solid line
dashed line
In the Acetaminophen lab, p-acetylaminophenol is the a. desired product b. side product c. by product
desired product
In the esterification lab, pentan-2-yl acetate is a. desired product b. side product c. by-product
desired product
What is the crystal on the center of the sample plate of the IR made of? a. diamond b. ruby c. emerald d. beryl
diamond
In the melting/boiling point, What is the identity of your unknown liquid in your melting point experiment? a. methanol b. tetrahydrofuran c. ethanol d. cyclohexene
ethanol
In the Biodiesel lab, What technique will you use to isolate the product? a. extraction b. crystallization c. distillation
extraction
In the esterification lab, What method will you use to isolate your product? a. recrystallization b. extraction c. distillation
extraction
In the esterification lab, Which technique will you use to purify your product? a. recrystallization b. extraction c. distillation
extraction
In the extraction lab, What is the name of the technique you will use to separate the mixtures this week? a. recrystallization b. thin layer chromatography c. extraction d. Melting Point
extraction
What word most closely describes the micropipettes? a. strong b. fragile c. sturdy
fragile
Will strong IMFs result in a higher boiling point for a liquid or a lower boiling point for a liquid? a. higher boiling point b. lower boiling point
higher boiling point
Which intermolecular force is likely to be the most important when the sample molecules are adsorbed onto the stationary phase on a TLC plate? a. hydrogen bonding b. dipole-dipole c. induced-dipole
hydrogen bonding
The ionized benzoic acid dissolves better in water than it does in diethyl ether, which is how and why it is extracted into the water phase. Give the TWO most important IMFs that are responsible for solubilizing the benzoic acid anion in the water. a. dipole-dipole forces b. ion-dipole forces c. hydrogen bonding d. Induced Dipole (London Dispersion Forces)
ion-dipole forces and hydrogen bonding
The ionized benzoic acid dissolves better in water than it does in diethyl ether, which is how and why it is extracted into the water phase. Give the TWO most important IMFs that are responsible for solubilizing the benzoic acid anion in the water. Give the most important IMF that is responsible for solubilizing the sodium cation in the water. a. dipole-dipole forces b. ion-dipole forces c. hydrogen bonding d. Induced Dipole (London Dispersion Forces)
ion-dipole forces and hydrogen bonding
In the melting/boiling point lab, Which intermolecular force do you think is primarily responsible for the difference in boiling point between 1-hexanol and nonanal (structures below)? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. A or C
ion-dipole forces or London dispersion forces
In your pharmaceutical formulation, benzoic acid is mixed with salicylic acid in a roughly 2:1 ratio. If you measured the melting point of this mixture, would the benzoic acid melt at a temperature that is the same as pure benzoic acid, or would it melt at a temperature lower than that of pure benzoic acid or at a temperature higher than that of pure benzoic acid? a. higher b. lower c. same
lower
The impure sample should at least start to melt at a much . temperature than the pure. Which of the following fits the blank? a. lower b. higher
lower
Which technique will you use to determine the purity of a solid sample? a. mixed melting point b. melting point c. boiling point d. mixed boiling point
melting point
In the Aspirin lab, What are the two methods you will use to characterize your product, i.e. to know how pure it is and what it is? a. melting point b. TLC c. IR spectroscopy d. NMR
melting point ant IR spectroscopy
In the solubility lab, Based on the density you determined for unknown Liquid 2, what do you think the identity of unknown Liquid 2 was? a. water b. methyl benzoate c. glycerol d. chloroform
methyl benzoate
Will you determine the limiting reagent by comparing weights or moles? a. weights b. moles
moles
In the esterification lab, Extraction of unreacted acetic acid into the water layer is aided by converting it from its neutral form into an ionic form because ions are more soluble in water. What is the charge on the acetic acid in its ionic form?
negative
When you added the aqueous base to the ether solution of the mixture, a chemical reaction occurred that transformed the benzoic acid from a neutral chemical into an ionic chemical with a charge. What was the sign of the charge on the ionized benzoic acid, negative (A) or positive (B)?
negative
Carbon tetrachloride is non-polar or polar
non-polar
Hexane is nonpolar or polar
non-polar
After using the pipette to dispense a liquid, in which circumstances it is okay to leave liquid in the tip. a. when you are saving the liquid for later b. when you want to dispense the liquid multiple times c. when you didn't want to dispense all of the liquid at once d. none of these circumstances
none of these circumstances
Toluene is non-polar or polar
nonpolar
In the Acetaminophen lab, Based on the number of moles of p-aminophenol and acetic anhydride, which is the limiting reactant or reagent? a. p-aminophenol b. Acetic anhydride
p-aminophenol
In the Acetaminophen lab, the reactant is a. water b. acetic anhydride c. p-aminophenol
p-aminophenol
In the Aspirin lab, What is the catalyst in this reaction? a. phosphoric acid b. salicylic acid c. acetic anhydride d. water
phosphoric acid
Acetone is polar protic or polar aprotic
polar aprotic
Diethyl ether is polar protic or polar aprotic
polar aprotic
Ethyl acetate is polar protic or polar aprotic
polar aprotic
acetonitrile is polar protic or polar aprotic
polar aprotic
Acetic acid is polar protic or polar aprotic
polar protic
Methanol is polar protic or polar aprotic
polar protic
water is polar protic or polar aprotic
polar protic
In the melting/boiling point lab, Breaking the IMFs ______ the energies of the electrons. Which of the following fits the blank? a. raises b. lowers
raises
In the Acetaminophen lab, a. distillation b. filtration c. crystallization d. recrystallization
recrystallization
IR spectra can be measured by passing IR radiation through a sample or by reflecting IR radiation off a sample. Which of these 2 methods will you use in your lab? a. passing IR radiation through a sample b. reflecting IR radiation off a sample
reflecting IR radiation off a sample
What is the name of the procedure where a reaction mixture is heated, the liquid/solvent boils, its vapors are condensed and drips back into the reaction vessel so that no liquid is lost? a. distillation b. condensation c. filtration d. reflux
reflux
In the Acetaminophen lab, p-aminophenyl acetate is the a. desired product b. side product c. by product
side product
In the esterification lab, (E)-hex-2-ene (alkene) is a. desired product b. side product c. by-product
side product
In the esterification lab, pentan-2-one (ketone) is a. desired product b. side product c. by-product
side product
In the esterification lab, You will need to extract the acid catalyst and any unreacted acid reactant using a base solution. What base will you use? a. sodium hydroxide b. sodium chloride c. sodium sulfate d. sodium bicarbonate
sodium bicarbonate
In the following diagram that illustrates solvation of diethyl ether in methanol, which type of line indicates the Covalent Bond between O and H? a. solid line b. dashed line
solid line
In the structure of hexanol above, which type of line represents an O-H covalent bond? a. dashed line b. solid line
solid line
In the solubility lab, In what container will you mix liquids to test miscibility? a. beaker b. flask c. vial d. test tube
test tube
What is the purpose of wrapping the boiling point apparatus with aluminum foil? a. to maximize heat loss b. to maximize cooling c. to minimize heat loss d. to protect from light
to minimize heat loss
In the Biodiesel lab, Is this reaction acid catalyzed or base catalyzed?
Base catalyzed
In the Biodiesel lab, What is the byproduct that is obtained in this reaction a. Triglyceride b. Methyl ester c. Methanol d. Glycerol
Glycerol
Benzoic acid is Polar Protic or Polar Aprotic. Benzoic acid is H-bond donor or H-bond acceptor or both
Polar Protic both
Diphenylamine is Polar Protic or Polar Aprotic. Diphenylamine is H-bond donor or H-bond acceptor or both
Polar protic both
Phenol is polar Protic or Polar Aprotic. Phenol is H-bond donor or H-bond acceptor or both
Polar protic both
Suppose, the mass of the starting p-aminophenol is 152 mg. Calculate the number of moles of the starting p-aminophenol. Molar mass of p-aminophenol = 109.1 g/mol
1.39 x*10^-3 moles
Suppose, the mass of the starting salicylic acid is 250 mg. Calculate the number of moles of salicylic acid. Molar mass of salicylic acid = 138.12 g/mol
1.81 * 10^-3 moles
The amount of material that is deposited on a TLC plate is very small and it would be impossible to weigh. But let's assume that you deposited 5 micrograms of acetaminophen on the plate. How many molecules would 5 micrograms be? Molar mass of acetaminophen = 151.2 g/mol Avogadro's number = 6.022 x 10^23
1.99 * 10^16 molecules
In the melting/boiling point lab, What is the Melting Range (in C) of Unknown Sample B?
123
In the melting/boiling point lab, What is the Melting Range (in C) of the Pure Unknown mixed with Benzoic Acid?
123
How many peaks in an IR spectrum would you expect to see that would characterize a carboxylic acid functional group? a. 1 b. 2 c. 3 d. 4
2
If you had 350 microliters of ethyl acetate, how many molecules of ethyl acetate would that be? Molar mass = 88.1g/mol Avogadro's number is 6.022 *10^23 density = 0.9 g/mol
2.15 *10^21 molecules
How many milliliters are there in 2560 microliters?
2.56
One problem with organic equations is that we tend to focus on what is happening to one molecule at a time, we forget that there are many, many molecules undergoing the reaction. Suppose, the mass of the starting salicylic acid is 200 mg. Calculate the number of molecules of salicylic acid. Avogadro's number = 6.022 x 10^23 Molar mass of salicylic acid = 138.12 g/mol
871000000000000000000
In the melting/boiling point lab, What is the Melting Range (in C) of Unknown Sample A?
95
Suppose, after recrystallization and subsequent filtration of your pure sample, you don't allow enough time for it to dry before measuring its weight. What do you expect your % recovery would be? a. <100% b. >100% c. Cannot be determined. Need more information.
>100%
In the Biodiesel lab, the catalyst is
potassium carbonate
In the solubility, What would the weight of ethyl acetate be if you had 350 microliters of ethyl acetate? Density = 0.90g/mL
0.315g
In the solubility lab, you were asked to measure the weights and calculate the densities of four different volumes (0.1 mL, 0.3 mL, 0.6 mL and 1.0 mL) of an Unknown Liquid 1. What is the average of the four densities (in g/mL) you calculated for Liquid 1?
0.81
What should the melting point range be for a pure substance? a. 3-5 degrees C b. 2-4 degrees C c. 5-10 degrees C d. 1-2 degrees C
1-2 degrees C
Assuming that you started with exactly 0.065 g of benzoic acid in your recrystallization, how many molecules of benzoic acid did you start with? You need to know that Avogadro's number is 6.022 x 10^23.
3.20 x 10^20 molecules
How many microliters are there in 0.36 mL?
360
Assuming that you started with exactly 0.065 g of benzoic acid in your recrystallization, how many moles of benzoic acid did you start with? Molar mass = 122.1g/mol
5.32 x 10^-4 moles
Suppose, the weight of the unknown mixture you started with is 142.3 mg. The weight of the extracted benzoic acid is 41.7 mg. The weight of the extracted naphthalene is 48.8 mg. You can combine the weights of the chemicals you isolated and compare that weight to the weight you started with to determine a percent recovery. Calculate the extraction recovery efficiency (i.e. percent recovery). Equation: % recovery = (combined weight of the isolated compounds/weight of the starting mixture) x 100 a. 93.5% b. 83.5% c. 73.5% d. 63.5%
63.5%
In the melting/boiling point lab, What is the Boiling Point Range (in C) of the Unknown Sample?
78
In the melting/boiling point lab, What is the Melting Range (in C) of the Pure Unknown?
78
Suppose the mass of the starting impure sample is 210 mg and the mass of the recrystallized pure sample is 180 mg. Calculate the % recovery? a. 66% b. 76% c. 86% d. 96%
86%
Suppose, after extraction, you did not allow enough time for the recovered benzoic to dry. Therefore, it was still wet when you measured its weight and calculated the percent recovery. Which of the following do you think might be your value for percent recovery? a. <100% b. >100% c. Cannot be determined. Need more information.
>100%
When you calculate a % recovery you will usually find that it is smaller than 100%. Which of the following are possible reasons for this phenomenon? a. The impurity has been separated out b. Mechanical losses (e.g. during transfers) c. Some of the compound is still in solution d. All of the above are possible reasons!
All of the above are possible reasons!
Your recovery is highly unlikely to be exactly 100%. Which of the following are possible reasons why your recovery is less than 100%? a. Mechanical losses (e.g. during transfers) b. Incomplete deprotonation c. incomplete reprotonation d. All of the above are possible reasons!
All of the above are possible reasons!
In the extraction lab, In this experiment, you will be using both an acid solution and a base solution. To extract an acid from a mixture into an aqueous solution and then recover it from the aqueous solution- A. You will add an acid solution in the first part to extract and then use base to recover the acid. B. You will add a base solution in the first part to extract and then use acid to recover the acid.
B
In the melting/boiling point, What is the identity of your unknown compound in your melting point experiment? a. Benzoic acid b. salicylic acid
Benzoic acid
in the recrystallization lab, Suppose, the melting range of the sample after purification by recrystallization is 120.9 - 123.2 C. The melting range of the pure sample mixed with salicylic acid is 112.3 - 150.2 C. The melting range of the pure sample mixed with benzoic acid is 122.3 - 123.8 C. Based on the above observations, which of the two pharmaceutical acids did you purify through recrystallization? In other words, what is the identity of the sample you purified? a. Benzoic acid b. Salicylic acid
Benzoic acid
In the solubility lab, Based on your experiments on solubility, which of the following solid-solvent combination is soluble? a. Biphenyl-water b. malonic acid-Diethyl ehter c. Benzophenone-Hexane d. Biphenyl-Hexane
Biphenyl-Hexane
Why does energy have to be supplied to a chemical in order to break the IMFs between the molecules in that chemical? a. Breaking the IMFs lowers the energies of the electrons b. Breaking the IMFs raises the energies of the electrons c. Breaking IMFs have nothing to do with the energy of electrons!
Breaking the IMFs raises the energies of the electrons
In the melting/boiling point lab, The sample mentioned in the previous question is known to be one of four known chemicals. These four known chemicals have melting points of A = 112-113°C, B = 115-116°C, C = 118-119°C and D = 121-122°C. Which of these known chemicals, A, B, C or D is most likely to be the unknown sample from the previous question? Hint: Pure samples have higher and narrower melting range. a. A b. B c. C d. D
D
Benzoic acid (an organic acid) is soluble in which of the following organic solvents? a. Diethyl ether b. water c. Sodium hydroxide (NaOH 6M) d. all of the above
Diethyl ether
In the extraction lab, In your extraction, the organic layer will mainly be the organic solvent. What organic solvent will you use? a. Dichloromethane b. Sodium hydroxide c. Diethyl ether d. Chloroform
Diethyl ether
In the extraction lab, How will you recover the naphthalene from its solution at the end of the extraction? a. By adding an acid to the solution b. Filter the solvent c. Evaporate the solvent d. By adding water to the solution
Evaporate the solvent
Extraction is usually a very good way of separating a mixture of organic chemicals, you should be able to isolate fairly pure materials after they are separated. Suppose, the observed melting point range of your isolated benzoic acid is 119 - 121 C. What will be your conclusion about the purity of the isolated benzoic acid? a. Fairly pure b. impure
Fairly Pure
Extraction is usually a very good way of separating a mixture of organic chemicals, you should be able to isolate fairly pure materials after they are separated. Suppose, the observed melting point range of your isolated naphthalene is 79 - 81 C. What will be your conclusion about the purity of the isolated naphthalene? a. Fairly pure b. impure
Fairly Pure
You are allowed to lay the micropipette on the lab bench with liquid in the tip. a. True b. False
False
In the melting/boiling point lab, What are the two most important intermolecular forces present in your unknown solid that needs to be broken in order to melt a solid sample of it? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. covalent boding
Hydrogen bonding and London dispersion forces
In the melting/boiling point lab,What are the two most important intermolecular forces present in your unknown liquid that need to be broken in order to boil a liquid sample of it? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. covalent bonding
Hydrogen bonding and London dispersion forces
Recrystallization "works" by allowing crystals of the desired compound to grow in a cooling solution, while excluding impurity molecules from the crystal because they will not "fit" properly in the highly ordered crystal. If any impurity molecules did manage to get into one of the forming crystals, what would be the effect on the melting point of that particular crystal? a. HIGHER and NARROW the melting range b. LOWER and NARROW the melting range c. LOWER and BROADEN the melting range d. HIGHER and BROADEN the melting range
LOWER and BROADEN the melting range
In the melting/boiling point lab, At room temperature, benzene is a liquid and naphthalene is a solid. Which intermolecular force is responsible for the higher melting point of naphthalene? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. hydrophobic interactions
London dispersion forces
How will you cool the solution below room temperature to maximize the quantity of crystals of pure acid that will form? a. Pour the solution on the ice bath b. Place the solution on an ice bath c. Blow air to the solution
Place the solution on an ice bath
In the recrystallization lab, How does temperature generally affect solubility, specifically the solubility constant S. a. Solubility (S) decreases at higher temperature b. Solubility (S) increases at higher temperature c. Solubility (S) has not effect on temperature
Solubility (S) increases at higher temperature
In the solubility lab, The following is a schematic representation of the molecules for forming a solution of the solid biphenyl in the liquid ethanol. Based on your experimental observations and the picture below, select the correct statements from the following. a. The IMF broken in biphenyl is induced dipole b. The IMF broken in ethanol is hydrogen bonding c. The IMF formed in solution is hydrogen bonding d. The energy cost to break IMFs in biphenyl is large e. The energy cost to break IMFs in ethanol is large f. The energy gain in making IMFs in solution is large g. Biphenyl is INSOLUBLE in ethanol
The IMF broken in biphenyl is induced dipole The IMF broken in ethanol is hydrogen bonding The energy cost to break IMFs in ethanol is large The energy gain in making IMFs in solution is large
Suppose, after recrystallization and subsequent filtration of a pure sample, a student doesn't allow enough time for it to dry before performing its melting point analysis. So, the sample is still wet with the solvent. The student observes that the melting range of the sample is both broader and lower than what is expected. What is a possible reason for this observation? a. The recrystallization was a failure b. The solvent is acting as an impurity c. The DigiMelt wasn't pre-heated to the appropriate temperature d. The DigiMelt instrument needs re-calibration
The solvent is acting as an impurity
What is the formula for describing the available thermal energy at any temperature? a. Thermal Energy = mcdT b. Thermal Energy = R log T c. Thermal Energy = RT d. all of the above
Thermal Energy = RT
In this experiment, the thermometer bulb should be positioned in the vapor and not in the liquid to determine the boiling point of your liquid. a. True b. False
True
True or False? During the extraction procedure, the organic layer will be on the top layer.
True
True or false? During the extraction process when you have both organic and aqueous solutions in immiscible layers, the naphthalene will be in the organic layer.
True
in the recrystallization lab, Suppose, the melting range of an impure sample is 105.7 - 111.1 C. After purification by recrystallization, the melting range of the sample was observed to be 120.2 - 122.3 C. Based on the above observations, did the recrystallization improve the purity of the sample? a. Yes. The melting range after recrystallization is higher and narrower. b. Yes. The melting range after recrystallization is higher and narrower.
Yes. The melting range after recrystallization is higher and narrower.
In the solubility lab, Below is a schematic representation of the molecules for forming a solution of the solid biphenyl in the liquid hexane. Based on your experimental observations and the picture below, select the correct statements from the following. a. the IMF broken in biphenyl is induced dipole b. the IMF broken in hexane is hydrogen bonding c. The IMF formed in solution is induced dipole d. The energy cost of breaking IMFs (to dissolve biphenyl in hexane) is small e. The energy gain of making IMFs (in solution) is large f. Entropy favors dissolving biphenyl in hexane g. Biphenyl is INSOLUBLE in hexane
a. The IMF broken in biphenyl is induced dipole c. The IMF formed in solution is induced dipole d. The energy cost of breaking IMFs (to dissolve biphenyl in hexane) is small f. Entropy favors dissolving biphenyl in hexane
When a crystal dissolves in a solvent, intermolecular forces in both the solid and the solvent are broken, and intermolecular forces between the solvent and the solute form. Shown below are molecules of the solid benzoic acid, water as the solvent, and a molecular representation of benzoic acid dissolved in water. Which of the following IMFs need to be broken in the solid acid when it dissolves in water? a. Hydrogen bonding b. dipole-dipole forces c. induced dipole (London dispersion forces) d. all of the above
all of the above
When a crystal dissolves in a solvent, intermolecular forces in both the solid and the solvent are broken, and intermolecular forces between the solvent and the solute form. Shown below are molecules of the solid benzoic acid, water as the solvent, and a molecular representation of benzoic acid dissolved in water. which of the following IMFs need to be broken in the solvent molecules when benzoic acid dissolves in water? a. Hydrogen bonding b. dipole-dipole forces c. induced dipole (London dispersion forces) d. all of the above
all of the above
When a crystal dissolves in a solvent, intermolecular forces in both the solid and the solvent are broken, and intermolecular forces between the solvent and the solute form. Shown below are molecules of the solid benzoic acid, water as the solvent, and a molecular representation of benzoic acid dissolved in water. which of the following IMFs need to be formed between the solvent molecules and the solute benzoic acid when benzoic acid dissolves in water? a. Hydrogen bonding b. dipole-dipole forces c. induced dipole (London dispersion forces) d. all of the above
all of the above
In the recrystallization lab, According to the procedure, how much solvent will you use to dissolve the acid when performing your recrystallization? a. as little as possible b. as much as possible c. exactly 3 drops
as little as possible
In the solubility lab, The following is a schematic representation of the molecules for forming a liquid mixture of acetone and water. Based on your experimental observations and the picture below, select the correct statements from the following. a. The IMF broken in acetone is hydrogen bonding b. The IMF broken in water is hydrogen bonding c. The IMF formed in the mixture is hydrogen bonding d. The energy cost to break the IMFs in both acetone and water is small e. The energy gain to make the IMFs in the mixture is large f. Acetone is IMMISCIBLE in water
b. The IMF broken in water is hydrogen bonding c. The IMF formed in the mixture is hydrogen bonding e. The energy gain to make the IMFs in the mixture is large
In the extraction lab, Name the organic compounds that are in the mixtures you will be given to separate in this experiment. a. benzoic acid b. benzoin c. diethyl ether d. naphthalene e. salicylic acid
benzoic acid and naphthalene
in the recrystallization lab, The names of the two acids that could potentially be your unknown acid are: a. benzoic acid and salicylic acid b. acetic acid and benzoic acid c. salicylic acid and acetic acid d. acetylsalicylic acid and salicylic acid
benzoic acid and salicylic acid
What are the color of the gloves the person was wearing in the YouTube recrystallization video? a. black b. red c. pink d. blue
blue
What color gloves was the user wearing in the video that showed you how to use a micropipette? a. blue b. red c. green d. gray
blue
Which technique will you use to determine the identity of a liquid sample? a. mixed melting point b. melting point c. boiling point d. mixed boiling point
boiling point
In the following diagram that illustrates solvation of diethyl ether in methanol, which type of line indicates the Hydrogen Bond between O and H? a. solid line b. dashed line
dashed line
will an impurity increase or decrease the melting point temperature of a pure sample? a. increase b. decrease
decrease
In the melting/boiling point lab, Which intermolecular force do you think is primarily responsible for the difference in boiling point between acetone and isobutane (structures below)? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. hydrophobic interactions
dipole-dipole forces
In the solubility lab, Based on this average density, what do you think the identity of unknown Liquid 1 was? a. pentane b. hexane c. ethanol d. pinene
ethanol
When should you change the tip on a micropipette? a. every time you plan to dispense your liquid b. at the beginning of your experiment c. never
every time you plan to dispense your liquid
Will strong IMFs result in a higher melting point for a solid or a lower melting point for a solid? a. higher melting point b. lower melting point
higher melting point
In the melting/boiling point lab, Which intermolecular force do you think is primarily responsible for the difference in boiling point between acetone and isopropanol (structures below)? a. ion-dipole forces b. Hydrogen bonding c. London dispersion forces d. hydrophobic interactions
hydrogen bonding
In the melting/boiling point lab, The melting point of an unknown sample (not yours) was taken and found to have a melting point range of 114 - 121°C. What can you conclude about the purity of this sample? a. pure b. impure
impure
Ideally, where are the impurities at the end of a recrystallization procedure? a. in the solid crystals b. in the solvent c. on the filter paper d. on the dry plate
in the solvent
will an impurity increase or decrease the melting point range of a pure sample? a. increase b. decrease
increase
The sodium sulfate is added to dry the diethyl ether solution. Sodium sulfate dries the solvent by forming strong intermolecular forces between it and the water. What are the TWO most important IMFs between sodium sulfate and water. a. dipole-dipole forces b. ion-dipole forces c. hydrogen bonding d. Induced Dipole (London Dispersion Forces)
ion-dipole forces and hydrogen bonding
In the solubility lab, What is the name of the device you will use in this lab to measure volumes of liquids accurately? a. transfer pipette b. micropipette c. graduated cylinder d. beaker
micropipette
In the meling and boiling point lab, which technique did you use to determine the identity of a solid sample? a. mixed melting point b. melting point c. boiling point d. mixed boiling point
mixed melting point
In the recrystallization lab, What technique is used for the identification of the unknown acid in this experiment? a. infrared spectroscopy b. mixed melting point c. mixed boiling point d. recrystallization
mixed melting point
In the recrystallization lab, What technique will you use to purify your pharmaceutical acid? a. melting point b. recrystallization c. reflux d. boiling point
recrystallization
In the solubility lab, In what container will you mix solids and solvents to test solubility? a. beaker b. flask c. vial d. test tube
test tube
In the recrystallization lab, Why do you need to heat the beaker that contains the solution of the acid you are recrystallizing? a. to melt the acid b. to do a chemical reaction c. to increase the solubility of acid in water
to increase the solubility of acid in water
In the extraction lab, The benzoic acid will be extracted into an aqueous layer. What liquid solvent will the aqueous layer mainly consist of (any solution that consists mainly of this solvent is described as aqueous)? a. water b. diethyl ether c. dichloromethane d. chloroform
water
In the recrystallization lab, What solvent will you use to do recrystallization? a. water b. ethanol c. acetone d. dichloromethane
water
