USC Organic Chemistry Review for Chemical Technician Licensure Exam

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Questions and Answers

Which of the following techniques can be used to visualize the spots in a TLC plate?

Use a UV 366 nm lamp

Use iodine vapors

Use a UV 254 nm lamp

Use visible light

All of the above (correct)

Given the experimental conditions provided, propose the elution order of a mixture containing an aromatic hydrocarbon, carboxylic acid, ether, and an alcohol with similar molecular weights.

Rt aromatic < Rt alcohol < Rt ether < Rt carboxylic acid

Rt carboxylic acid < Rt alcohol < Rt ether < Rt aromatic (correct)

Rt carboxylic acid < Rt alcohol < Rt aromatic < Rt ether

Rt aromatic < Rt ether < Rt alcohol < Rt carboxylic acid

Rt carboxylic acid < Rt ether < Rt alcohol < Rt aromatic

Which of the following statements would best describe reverse phase chromatography?

Stationary and mobile phases are both non-polar

Polarity of both phases doesn’t matter

Stationary phase is non-polar and mobile phase is polar (correct)

Stationary phase is polar and mobile phase is non-polar

Stationary and mobile phases are both polar

Which of the following statements about chromatography is correct?

The longer the retention time means that the analyte has a strong affinity to the stationary phase Signup and view all the answers

The carbon atom in urea is:

sp3 hybridized Signup and view all the answers

What is the relationship of the following pair of compounds?

position isomer Signup and view all the answers

What functional group is present in the terpene, camphor?

carbonyl Signup and view all the answers

What functional class is represented by the alkaloid, coniine?

amine Signup and view all the answers

Which of the following compounds would be the most soluble in water?

ethyl alcohol Signup and view all the answers

Which of the following compounds has the lowest boiling point?

CH3-O-CH3 Signup and view all the answers

Which of the following pairs of compounds are constitutional isomers?

Both C and D Signup and view all the answers

How many structurally distinct sets of hydrogen atoms are present in (CH3)3CCH2OCH3?

2 Signup and view all the answers

What is the correct IUPAC name for the given compound?

Methyl p-chlorobenzoate Signup and view all the answers

The structure below has ________.

1º and 2º carbon atoms Signup and view all the answers

Which compound is the likely product from addition of Cl2 to 1-butene?

CH3CH2CHClCH2Cl Signup and view all the answers

What is the correct name for the compound below?

4,4-dimethyl-2-cyclohexenol Signup and view all the answers

In which of the following groups are compounds arranged in increasing volatility?

CH4, CH2Cl2, CH3Cl, CHBr3 Signup and view all the answers

How much hyoscyamine would be found in the diethyl ether layer after the extraction process?

0.135 g Signup and view all the answers

What could have happened to account for the technician's low yield in recrystallizing acetylsalicylic acid?

Acetylsalicylic acid is soluble in hot water but insoluble in cold water. Signup and view all the answers

In recrystallization, what is charcoal typically used for?

Remove colored impurities Signup and view all the answers

What is a key feature of a good recrystallization solvent?

Solute must be insoluble in hot solvent and soluble in cold solvent Signup and view all the answers

Which of the following statements describes a wrong technique regarding melting point determination?

Crystal inside the capillary tube must be next to the thermometer’s mercury bulb Signup and view all the answers

What would be the observed melting point if urea and succinimide were mixed in a 1:1 ratio?

Equal to 132°C Signup and view all the answers

Complete the following sentence: Melting point of a pure substance is defined as___

Temperature at which the crystals was completely melted Signup and view all the answers

When is it time to record the boiling point of a liquid solution?

When the capillary gives off a steady stream of bubbles Signup and view all the answers

A constant boiling mixture of two or more components in a solution is called

An azeotrope Signup and view all the answers

Based on the vapor-liquid plot, which of the following statements is TRUE?

The vapor pressure of compound A is less than compound B Signup and view all the answers

Which of the following is the correct way of drying organic solvents?

Placing organic solvent in a desiccator overnight Signup and view all the answers

What does the label 29/32 on laboratory glassware with ground glass joints signify?

The inner diameter 29mm with length of 32mm Signup and view all the answers

How do we properly apply grease in the ground glass joints?

Place a thin coating in the female joint and mate the joints by rotating the other half Signup and view all the answers

A reaction needs to be carried out in an anhydrous environment at very high temperatures, which of the following should be a part of the setup?

Drying tube and an air condenser Signup and view all the answers

Which of the following statements is incorrect about the west condenser?

A condenser without water can act as an air condenser Signup and view all the answers

How would a technician transfer 60 mL of ethanol to a 100-mL graduated cylinder from a 2.5L amber bottle?

Pour a small amount of liquid in a clean beaker then transfer to the graduated cylinder Signup and view all the answers

Which of the following apparatus can be used to weigh a solid sample to the nearest 0.0001 g?

Microbalance Signup and view all the answers

Study Notes

Organic Chemistry Review

Structure of Urea

The carbon atom in urea is sp3 hybridized.

Functional Groups

Camphor is a terpene with a carbonyl functional group.
Coniine is an alkaloid with an amine functional group.

Solubility

Ethyl alcohol is more soluble in water than dichloromethane, cyclohexane, and chloroform.
The order of increasing volatility is: CH4, CH2Cl2, CH3Cl, CHBr3.

IUPAC Nomenclature

The correct IUPAC name for a given compound is determined by the structure of the compound.
Examples: 1-chloro-2-methylpropane, 2-chloro-2-methylbutane, 4,5-dimethyl-1-hexene.

Constitutional Isomers

Constitutional isomers are molecules with the same molecular formula but different structures.
Examples: CH3CH2OCH3 and CH3CH2CHO, CH3CH2CH2CHO and CH3COCH2CH3.

Physical Properties

The boiling point of a compound is related to the strength of intermolecular forces.
The order of increasing boiling points is: butane, butanone, 1-butanol, butanoic acid.

Spectroscopy

Infrared (IR) spectroscopy is used to determine the structure of organic molecules.
Different functional groups absorb at specific wavenumbers in the IR spectrum.
Examples: N-H, C-H, and O-H stretching and bending motions absorb at 4000-2500 cm-1.

Filtration Techniques

Vacuum filtration is used to collect filtrate.
Gravity filtration is used to collect crystals.
Hot gravity filtration is used to filter hot solutions.

Recrystallization

Recrystallization is a purification technique used to separate a solid from a solution.
A good recrystallization solvent should have a high solubility for the solid at high temperatures and a low solubility at low temperatures.

Melting Point

The melting point of a pure substance is the temperature at which the solid begins to melt.
The melting point of a mixture is lower than that of a pure substance.

Distillation

Distillation is a purification technique used to separate a mixture based on boiling points.
A fractionating column is used to separate a mixture of compounds with similar boiling points.

Laboratory Techniques

Ground glass joints are used to connect glassware.
Grease is used to lubricate ground glass joints.
A drying tube is used to dry a reaction mixture.
A reflux condenser is used to convert vapors into a liquid during distillation.### Laboratory Techniques and Safety

Measurement and Heating Techniques

A glass pipette is accurate for measuring 50 μL solutions.
Analytical balances can measure solid samples up to 0.0001 g.
A heat gun should not be used for microscale reactions.
Steam baths are suitable for heating flammable solvents.
Water baths can heat solvents below 90°C.

Chromatography

Thin-Layer Chromatography (TLC) can determine sample purity and identity.
TLC plates must not be heated before use.
Concentrated samples should not be spotted repeatedly on TLC plates.
The Rf value depends on the polarity of the substance and the stationary phase.

Column Chromatography

Reverse-phase chromatography has a non-polar stationary phase and a polar mobile phase.
In Reverse-Phase Chromatography, the longer the retention time, the stronger the affinity to the stationary phase.
The area under the elution band indicates the quantity of the solute.

Gas Chromatography

Helium, nitrogen, and argon are common carrier gases for GC.
Open tubular or capillary columns are preferred over packed tubular columns for better resolution.

Headspace Analysis

Headspace analysis is used to analyze volatile compounds from solid or liquid samples.

Laboratory Safety

Gloves: Nitrile gloves are suitable for handling concentrated hydrochloric acid, while butyl gloves are not.
In case of an earthquake, duck, cover, and hold first.
Ethanol vapour can catch fire at temperatures above 13°C.
Waste liquids with pH ≤ 2 or ≥ 12.5 are corrosive.
The GHS pictogram indicates the type of hazard.

Safety Data Sheets (SDS)

The SDS provides information on handling and storage, exposure control, and emergency procedures.
Two signal words (Danger and Warning) indicate the relative level of severity of hazard.
End-users should have access to the SDS.

Chemical Regulation and Inventory

The Chemical Control Order (CCO) regulates mercury, cyanide, and polychlorinated biphenyls.
Regular physical chemical inventory updates eliminate unneeded chemicals and ensure safe storage.

Emergency Preparedness and Response

Emergency equipment should be easily accessible and regularly inspected.
Mitigation phase efforts minimize the likelihood of incidents and limit their effects.

Green Chemistry

Green Chemistry aims to reduce or eliminate the use and generation of hazardous substances.

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Description

Practice questions for the USC Chemical Technician Licensure Exam, covering organic chemistry topics. Review and test your knowledge of chemical structures and bonding.