OCHEM Lab Final GJ
Considering the reaction of bromine with the following alkene: CH3+H-C=C-CH3+H Which structure shows the correct bonding for the product?
H, Br and CH3 on the top CH3, Br, and H bottom only single bonds
Primary and secondary alcohols can be oxidized by the addition of an oxidant like chromic acid or chromate. What is the product of oxidizing 1-propanol with the shown structure?
H3C-C H2-C=O-H
In general, when a hydrocarbon is added to water, the hydrocarbon will _____________ the water because hydrocarbons are _______________ than water.
-float above -less dense
For a reaction rate based on one reactant, identify the type of graph that will give a linear plot in each case. First order reaction ____________
In[reactant] vs. time
Considering the reaction of bromine with the following alkene: CH3+H-C=C-CH3+H Where would the Bromine attack to join the alkene?
It would break the double bond and bond to the carbons with a free bonding site.
When it is time to end a reflux, first ________________ and then turn off the heat. __________________ until the system has cooled.
-lower the heat source -leave the condenser water on
Assuming all other factors are held constant, you observe that an increase in the concentration of the reactant in solution causes the reaction rate to increase exponentially. What order of reaction is this?
Second order.
The term SN1 describes a reaction is a(n) __________________ involving __________________________.
-nucleophilic substitution. -One molecule in the rate-determining step.
For a reaction rate based on one reactant, identify the type of graph that will give a linear plot in each case. Second order reaction ____________
1/[reactant] vs. time
What is the correct reading of the volume in the pictured buret? Make sure to report your reading with the appropriate significant figures.
17.32 mL
Suppose you are performing a titration. At the beginning of the titration, you read the titrant volume as 2.08 mL. After running the titration and reaching the endpoint, you read the titrant volume as 28.78 mL. What volume, in mL, of titrant was required for the titration?
26.7 mL
A positive Baeyer's test appears as?
A brown precipitate.
A positive Jones's test appears as?
A color change to green.
A positive bromine test appears as?
A colorless solution.
A negative Baeyer's test appears as?
A purple solution
Using the letters on the image, identify each component of the titration set-up.
A. 0.00 mark B. barrel C. stopcock D. collection flask E. buret clamp
Which hydrocarbon group is the least reactive and why?
Alkane groups are the least reactive since they contain only sigma bonds between C-C's and C-H's, which are strong enough to demand high amounts of energy for participation in chemical reactions.
Describe what constitutes an Alkane.
Alkanes only have single bonds, whether in a linear or cyclic formation. Alkanes in a ring formation are often called cycloalkanes.
_______________ are saturated by hydrocarbons.
Alkanes.
Describe what constitutes an Alkene.
Alkenes have at least one double bond. Cyclic alkene structures can specifically be called cycloalkenes.
Baeyer's test, also known as the permanganate test, shows the presence of?
Alkenes.
___________________ are unsaturated hydrocarbons.
Alkenes.
The bromine test shows the presence of?
Alkenes. The bromine test indicates the presence of alkenes and alkynes through their reaction with bromine.
Describe what constitutes an Alkyne.
Alkynes have at least one triple bond. Cyclic alkynes generally do not exist because of the linear arrangement around the bond.
Why is potassium hydroxide preferred over sodium hydroxide in organic reactions? Select one: -Potassium hydroxide has a higher melting point. -Potassium hydroxide has a smaller cation as the counterion. -Potassium hydroxide is a stronger base. -Potassium hydroxide is more soluble in organic alcohols.
-Potassium hydroxide is more soluble in organic alcohols.
An SN2 reaction is a type of __________________ in which the nucleophile attacks the electrophile ______________ a leaving group leaves. The rate of the reaction depends on the concentration of ________________.
-Substitution reaction -At the same time -Both reactants
A negative bromine test appears as?
An orange solution.
A negative Jones's test appears as?
An orange solution. If only tertiary alcohols or no alcohols or aldehydes are present, the solution remains the orange color of the chromium(VI) in chromic acid.
Describe what constitutes an Aromatic compound.
Aromatic compounds have specific requirements. An aromatic hydrocarbon has carbons in a ring and alternating single and double bonds, which create stability through the delocalization of the electrons. The most common aromatic ring size is six carbons but others do exist.
When working in a fume hood, what is the best position of the hood sash? Select one: -Completely closed -As low as possible, no more than halfway up -At eye level -As high as possible, to the top of the hood
As low as possible, no more than halfway up.
Assuming all other factors are held constant, you observe that the reaction rate increases in direct proportion to the concentration of the reactant in solution. What order of reaction is this?
First order.
Describe the complete role of the acid catalyst in the dehydration of an alcohol. Select one: -The acid deprotonates the hydroxyl group and then the conjugate base protonates an adjacent carbon. -One acid molecule deprotonates the hydroxyl group and then another acid molecule deprotonates an adjacent carbon. -The acid protonates the hydroxyl group and then the conjugate base deprotonates an adjacent carbon. -One acid molecule protonates the hydroxyl group and then another acid molecule protonates an adjacent carbon.
The acid protonates the hydroxyl group and then the conjugate base deprotonates an adjacent carbon.
What are the concerns presented by overheating a distillation to a dry flask? Select one or more:
The remaining solid residue might contain explosive peroxides. The empty glassware might heat quickly, igniting vapors from the distillation.
Many reflux procedures involve a required length of time for the reflux to occur. When should you start timing the reflux for the procedure? Select one: -When the reflux ring stabilizes in the condenser. -When the reflux ring passes the top of the condenser. -When the sample is transferred to the flask. -When you turn on the heat under the flask.
When the reflux ring stabilizes in the condenser.
Identify the type of hydrocarbon represented by each structure.
alkane
Identify the type of hydrocarbon represented by each structure.
alkane 2
Identify the type of hydrocarbon represented by each structure.
alkene
Identify the type of hydrocarbon represented by each structure.
alkene 1
Identify the type of hydrocarbon represented by each structure.
alkyne
A hydrocarbon is unsaturated if _______________ are present.
any multiple bonds.
2. Identify the best description of the role each species plays in the SN2 synthesis of nerolin. KOH
base
1. The addition of chromic acid or chromate is a qualitative test for alcohols as the reaction causes a color change. However, not all alcohols react with chromic acid or chromate. Determine whether the named alcohol will react with chromic acid or chromate to cause a color change. 1-butanol
color change
2. The addition of chromic acid or chromate is a qualitative test for alcohols as the reaction causes a color change. However, not all alcohols react with chromic acid or chromate. Determine whether the named alcohol will react with chromic acid or chromate to cause a color change. 2-pentanol
color change
3. The addition of chromic acid or chromate is a qualitative test for alcohols as the reaction causes a color change. However, not all alcohols react with chromic acid or chromate. Determine whether the named alcohol will react with chromic acid or chromate to cause a color change. 3-hexanol
color change
Consider the structures of 1-hexanol and cyclohexanol. In the presence of acid and heat, __________ will undergo a more effective dehydration reaction because it is a _____________ alcohol and the ___________ in the intermediate of the mechanism will be more stable.
cyclohexanol, secondary, cation
When performing the acid-catalyzed dehydration of an alcohol, the yield of product can be increased by ___________ during the reaction.
distilling off the product
5. Identify the best description of the role each species plays in the SN2 synthesis of nerolin. I-CH2CH3term-57
electrophile
Concentration data is commonly monitored during a reaction to determine the order with respect to a reactant. Consider the types of observations listed, and determine which order is likely for that reactant. Assume all other factors are held constant. The reaction rate increases in direct proportion to the concentration of the reactant in solution.
first order
The biggest concern of working with hydrocarbons in lab is that many of them are
flammable
Therefore, hydrocarbons should be handled __________ to contain any associated vapors with that hazard
in the hood
Which changes can be made to a chemical reaction in order to increase the rate constant? Select one or more:
increases the temperature add a catalyst
1. Identify the best description of the role each species plays in the SN2 synthesis of nerolin. I- (iodine -)
leaving group
The addition of chromic acid or chromate is a qualitative test for alcohols as the reaction causes a color change. However, not all alcohols react with chromic acid or chromate. Determine whether the named alcohol will react with chromic acid or chromate to cause a color change. 3-ethyl-3-pentanol
no color change
3. Identify the best description of the role each species plays in the SN2 synthesis of nerolin.
nucleophile
2. Determine the type of alcohol represented by each structure.
phenol
4. Determine the type of alcohol represented by each structure.
phenol
5. Determine the type of alcohol represented by each structure.
primary
7. Determine the type of alcohol represented by each structure.
primary
Determine the type of alcohol corresponding to each given description or name. 1-pentanol
primary
Determine the type of alcohol corresponding to each given description or name. An alcohol with one other carbon attached to the carbon with the hydroxyl group
primary
4. Identify the best description of the role each species plays in the SN2 synthesis of nerolin.
product
The dehydration is ___________, and removing the product from ____________ reduces the ___________ reaction
reversible the reaction flask hydration
Concentration data is commonly monitored during a reaction to determine the order with respect to a reactant. Consider the types of observations listed, and determine which order is likely for that reactant. Assume all other factors are held constant. An increase in the concentration of the reactant in solution causes the reaction rate to increase exponentially.
second order
3. Determine the type of alcohol represented by each structure.
secondary
6. Determine the type of alcohol represented by each structure.
secondary
Determine the type of alcohol corresponding to each given description or name. An alcohol with two other carbons attached to the carbon with the hydrterm-25oxyl group
secondary
Determine the type of alcohol corresponding to each given description or name. 2-hexanol
secondary alcohol
1. Determine the type of alcohol represented by each structure.
tertiary
Determine the type of alcohol corresponding to each given description or name. An alcohol with three other carbons attached to the carbon with the hydroxyl group
tertiary
Determine the type of alcohol corresponding to each given description or name. 3-ethyl-3-pentanol
tertiary alcohol
Concentration data is commonly monitored during a reaction to determine the order with respect to a reactant. Consider the types of observations listed, and determine which order is likely for that reactant. Assume all other factors are held constant. The reaction rate is constant regardless of the amount of reactant in solution.
zero order
If crystal growth does not start on its own after the solution in the flask returns to room temperature, identify the best ways to promote this process. Select one or more: -Add ice cubes to the solution. -Add a bit of solid as a seed crystal. -Place the flask on a hot plate to evaporate some solvent. -Scratch the bottom of the flask gently with a stirring rod.
-Add a bit of solid as a seed crystal. -Scratch the bottom of the flask gently with a stirring rod.
Consider the SN2 reaction of an alcohol with an alkyl halide in the presence of base. The __________ should be added to the alcohol first to _________________ the alcohol and allow it to attack the __________________.
-Base -Deprotonate -Alkyl halide
Bromothymol blue is an indicator that appears _________ in basic conditions and ____________ in acidic conditions.
-Blue -Yellow
When working in the fume hood, it is important to make an effort to minimize ___________. Only keep items in the hood if they are being used for ____________________. Do not __________ chemicals in the fume hood unless instrterm-54ucted to do so.
-Clutter -The current experiment -Store
In general, when hydrocarbons like oil are added to water, the two liquids ________________ because hydrocarbons are ______________ and water is _________________.
-Do not mix -non-polar -polar
The dehydration of a secondary alcohol, like cyclohexanol, is a mechanism that occurs ______________. First, the alcohol is protonated to _______________________, creating _______________ intermediate. Then, a ______________ is removed, moving the electrons from that bond to make a ____________________ bond.
-In two steps -Leave as a water molecule -A cation -Hydrogen ion -Carbon-Carbon Double
Which tests can be used to show that a phenol is present? Select one or more: -Lucas test -Iron (III) chloride test -Iodine test -Acidity test
-Iron (III) chloride test -Acidity test
If the SN2 reaction of an aromatic alcohol with an alkyl halide, like the synthesis of nerolin, is successful, what changes would be seen in the IR spectrum for the product compared to the starting material? Select one or more: -The disappearance of a C-O bond from the starting material -The addition of a C-X band, where X is a halide, in the product -The disappearance of an O-H band from the starting material -The addition of sp3 C-H bands in the product
-The disappearance of an O-H band from the starting material -The addition of sp3 C-H bands in the product
In general, alcohols _________ when mixed with water because the ____________ in alcohols can ________________ with water.
-dissolve -O-H bonds -hydrogen bond
What is the best safety approach when working with unknown chemical substances? Select one: -Assume that any substance distributed to lab participants is non-toxic and not a safety risk. -Assume that the substance is hazardous. Always wear appropriate PPE and take steps to prevent contact. -Read the procedure and try to guess what the unknown substance is, then review its specific safety information. -Do not begin working with a substance unless you know exactly what it is.
Assume that the substance is hazardous. Always wear appropriate PPE and take steps to prevent contact.
Where should the tip of the thermometer be placed in a microscale distillation set-up? Select one:
At or slightly below the side arm fo the distillation head
What is observed when mixing alkanes, alkenes, and aromatics with one another?
Because they are all non-polar, they all form a homogenous mixture. If even one of them were polar, they would not mix together.
Write the balanced equation for calcium carbide (CaC2) reacting with water to give off ethyne (acetylene) when reacted with water.
CaC2 + 2 H2O ---> C2H2 + Ca(OH)2
A hydrocarbon is saturated if ______________ are present.
Only single bonds.
Regarding structure, what typically determines whether a molecule is more polar than another?
Polarity of a molecule increases when the molecule does not have opposing dipoles or a large non-polar section. Molecules or sections of molecules with only carbon and hydrogen are not polar. The most polar molecule in the list is the short alcohol. The ether has dipoles that are symmetrical and decrease the overall polarity. The longer alcohol has a larger non-polar section, which decreases the molecule's polarity overall.
Jones's test, also known as the chromic acid test, shows the presence of?
Primary or secondary alcohols.
Why does the dehydration of an alcohol more often use concentrated sulfuric acid, H2SO4, as the acid catalyst rather than dilute hydrochloric acid, HCl?
The additional water solvent from a dilute solution could reverse the dehydration reaction. The presence of the chloride ion could result in a competing substitution reaction.
In a molecule that contains a phenolic functional group, what properly identifies the phenol?
The benzene ring directly attached with the hydroxyl group.
How can a catalyst be recognized in a mechanism?
The catalyst is used and then regenerated in a later step.
If the dehydration reaction of an alcohol is successful, what changes would be seen in the IR spectrum for the product compared to the starting material? Select one or more:
The disappearance of an O-H band from the starting material The addition of a C-C double bond band in the product The disappearance of a C-O band from the starting material
For a reaction rate based on one reactant, identify the type of graph that will give a linear plot in each case. Zero order reaction ___________
[reactant] vs. time
