Quiz Questions Flashcards by Rania Benromdhane

Which of the following factors determines whether a solute will dissolve in a solvent?

molecular dipoles, molecular geometry, intermolecular forces, electrostatic attraction

How well did you know this?

Not at all

Perfectly

What are the strongest intermolecular forces that must be overcome when melting menthol?

hydrogen bonding

How well did you know this?

Not at all

Perfectly

steps for using a digital balance in the correct order

Determine the container to weigh chemicals into: small beaker, weighing paper, or weighing boat
Place the weighing container on the balance pan and press “Tare” or “Zero”
Use a spatula to transfer solid chemical into the container
Close the draft shields and record the mass once the reading has stabilized
Use a brush or paper towel to clean up spills in and around the balance

How well did you know this?

Not at all

Perfectly

WHat effect do impurities or solutes have on the melting point of a substance?

impurities lower the melting point

How well did you know this?

Not at all

Perfectly

when impurities lower the melting point what is the colligative property called

freezing point depression

How well did you know this?

Not at all

Perfectly

A solution is created when a small amount of ______ dissolves in a larger amount of _______. When a solutions concentration is reported in moles of _____ per liter of solution, the concentration is reported as a _____. When a solution’s concentration is reported in moles of ____ per _____ of solvent, the concentration is reported as a _______

solute, solvent, solute, molarity, solute, kilogram, molality

How well did you know this?

Not at all

Perfectly

molality equation

moles of solute/ kg of solvent

How well did you know this?

Not at all

Perfectly

what is the freezing point depression constant folrmula

Tf(solvent)- Tf(solution)= Kf x molality

How well did you know this?

Not at all

Perfectly

The most probable laboratory emergencies are chemical spills, minor burns and cuts, and fires. Which of the following statements are TRUE about responding to emergencies?

If possible turn off lab equipment before leaving lab for a fire alarm
Stay calm
Know where the stairwells are
All laboratories must have two exits

ALL ARE TRUE

How well did you know this?

Not at all

Perfectly

Which of the following statements are true

Cinnamic Acid dissolves into melted menthol
Cinnamic acid does not stay dissolved in solid menthol
Cinnamic Acid solidifies when menthol freezes
Menthol dissolves when heated
None of these

Cinnamic Acid dissolves into melted menthol
Cinnamic acid does not stay dissolved in solid menthol

How well did you know this?

Not at all

Perfectly

how to determine the molar mass of the unknown

Temp f (solvent)- Tempf(solution)= kf x ((mass of unknown/molar mass of unknown)/ kg of solvent)

How well did you know this?

Not at all

Perfectly

Because the three possible unknowns (cinnamic acid, vanillin and 4-hydroxybenzaldehyde) have either carboxylic acid or phenol functional groups, they are all weak acids.

How will this weak acidity affect the freezing point depression?

the solution freezing point is lower than it should be

How well did you know this?

Not at all

Perfectly

Because the three possible unknowns (cinnamic acid, vanillin and 4-hydroxybenzaldehyde) have either carboxylic acid or phenol functional groups, they are all weak acids.

What is the source of this effect?

more particles are in solution because of dissociation

How well did you know this?

Not at all

Perfectly

Because the three possible unknowns (cinnamic acid, vanillin and 4-hydroxybenzaldehyde) have either carboxylic acid or phenol functional groups, they are all weak acids.

How will the calculated molecular mass differ from the actual value?

The calculated molecular mass is lower

How well did you know this?

Not at all

Perfectly

Open Odyssey, go to the Miscellaneous tab, find the Solutions section and click on M I2 Molarity vs Molality. Follow the instructions on the screen and click on all the available buttons.

Why is molality used instead of molarity in this project?

Volume changes with temperature

How well did you know this?

Not at all

Perfectly

Open Odyssey, go to the Miscellaneous tab, find the Solutions section and click on M I2 Molarity vs Molality. Follow the instructions on the screen and click on all the available buttons.

Under what conditions are the values of molarity and molality very different?

high concentrations

How well did you know this?

Not at all

Perfectly

Open Odyssey, go to the Miscellaneous tab, find the Solutions section and click on M I2 Molarity vs Molality. Follow the instructions on the screen and click on all the available buttons.

Which value is higher?

molality

How well did you know this?

Not at all

Perfectly

Which of the following common household products contain flammable chemicals?

gasoline, rubbing alcohol, nail polish remover, antifreeze

How well did you know this?

Not at all

Perfectly

which of the following are ways to stop a fire?

remove ignition sources, place a beaker over a small flame to remove oxygen, ground metal container to prevent static electricity, limit quantities of flammable substances in work area

How well did you know this?

Not at all

Perfectly

Which of the following statements are true about flammability?

Inflammable is another word for flammable
A fire cannot start above or below a vapor’s flammability limits

How well did you know this?

Not at all

Perfectly

The National Fire Protection Association (NFPA) diamond has a [A] section for flammability. If the number [B] appears in this section, the chemical is extremely flammable. If the number [C] appears in this section, the chemical is a combustible, it will catch fire when heated. The Global Harmonized System (GHS) symbol is a picture of a [D]. If the hazard category is [E], the chemical is extremely flammable. If the hazard category is [F], the chemical is combustible.

red, 4, 2, fire, HC1,HC4

How well did you know this?

Not at all

Perfectly

A mixture of acetone and heptane is used in this project to create the TLC eluent. Only a small amount of liquid
(2−3mL)is needed for the development chamber, so the volume to volume ratios of heptane to acetone must be converted to reasonable quantities so that excess waste is not created. If the total volume is 2−3mL fill in the table to show how much of each chemical is needed to make the ratio.
Heptane : Acetone Ratio of 1:1
Heptane : Acetone Ratio of 1:2
Heptane : Acetone Ratio of 2:1
Heptane : Acetone Ratio of 3:2

1 mL Heptane : 1mL Acetone
1 mL Heptane : 2mL Acetone
2 mL Heptane : 1mL Acetone
1.5 mL Heptane : 1mL Acetone

How well did you know this?

Not at all

Perfectly

The ratio between the solvents should be reasonably precise, but not as precise as when making standard solutions for a Beer’s Law plot. What is the best piece of glassware to measure out the above volumes?

graduated cylinder

How well did you know this?

Not at all

Perfectly

Order the steps for preparing and developing a TLC plate.

With a pencil, draw a baseline
Use a capillary to deliver 1-2 drops of concentrated analyte solution
Allow the analyte spots to dry
Place plate in TLC chamber so that it doesnt touch the filter paper
Cap TLC chamber
Remove plate before solvent front reaches the top of the plate
Mark the solvent front
Measure distances to calculate Rf values

How well did you know this?

Not at all

Perfectly

when looking at a TLC which compound is more polar?

the compound that moves the least

which compound is most attracted to the eluent

the compound that moves the most/ is closest to the solvent front

Match the TLC issue with the cause. All the analyte spots are in the upper region of the TLC plate & close together

the eluent was too polar

Match the TLC issue with the cause. Analyte spots moved up the plate diagonally instead of vertically

The TLC plate was touching the filter paper wick

Match the TLC issue with the cause. While spotting the analyte spot became too large

The TLC plate was not allowed to dry between drops

Match the TLC issue with the cause. Rf values differ for 2 identically spotted plates from the same developing chamber containing 2:1 acetone:heptane eluent

The developing chamber is not capped resulting in evaporation

Which of the following are true statements about fume hoods? (Select all that apply)

the window on the front of the fume hood is called a sash a tissue paper held at the bottom of a sash should blow into the hood All work should be done at least 6 inches inside the hood room air should be drawn into the fume hood

PEL?

permissible exposure limit

odor threshold

gas concentration that 50% of the population can detect

odor fatigue

decreased sensitivity to odor over time

IDLH?

immediate dangerous to life and health

OEL?

occupational exposure limits

How can you tell if a chemical is hazardous after you smell it? Which of these chemicals will you smell after it becomes hazardous?

basically PEL has to be lower than odor threshold hexane: 50 ppm (PEL), 130 ppm(odor threshold) dichloromethane: 25ppm (PEL), 130 ppm(odor threshold) methanol: 200ppm (PEL), 5900ppm (odor threshold)

what is the major underlying principle of chromatography?

separation will be achieved if one component adheres to the stationary phase more than the other component does

A student dissolved a product in acetone and spotted on a silica TLC plate to determine the purity of the product. A 2:1 mixture of heptane:acetone was placed in the developing chamber. a) In this setup, silica is the:

stationary phase

mobile phase eluent

you have a tlc where the standard C does move from the baseline why didn't C move from the baseline

C is strongly absorbed to the silica bc of its polarity

which of the following statements are true about the permanganate?

most of the plate turns pink because unreacted permanganate is pink if a compound has a double binds its TLC spots turn yellow

Odyssey data: Carvone dipole moment is 4.1 Dihydrocarveol dipole 2.1 Limonene: 0.2 Which compound will travel the furthest up the TLC plate?

limonene bc its the most nonpolar

The compound that travels the furthest up the TLC plate will have the ________ Rf Value

largest

Odyssey data: Carvone dipole moment is 4.1 Dihydrocarveol dipole 2.1 Limonene: 0.2 c) View the electrostatic potential maps of each molecule by clicking on the icon. Which molecule has the least amount of red and blue coloring?

limonene- bc its most nonpolar aka least polar

Odyssey data: Carvone dipole moment is 4.1 Dihydrocarveol dipole 2.1 Limonene: 0.2 Do the dipoles in Odyssey correctly predict the Rf values of the other two compounds?

No, dihydrocarveol's dipole should be larger

which statement about gloves is true?

no glove material protects against all chemicals gloves should be removed when they come into contact with any hazardous chemicals

permeation

ability of a chemical to penetrate the glove material through small pores

degradation

destructive change in the glove material

breakthrough time

time for the first appearance of a chemical on the other side of the glove

rate of transfer

speed at which a chemical appears on the other side of the glove

which of the following are true about lab coats

sleeves should never be rolled up Lab coats should never be worn outside of lab

nitrile gloves are used in general and organic chemistry laboratory. which of the following statements are TRUE about nitrile gloves

nitrile gloves protect well against an aliphatic hydrocarbons like heptane and limonene

Which of the following guidlines should be followed to protect your skin in the chemistry laboratory

use gloves when appropriate to do so wear clothing that covers most of your body wear a lab coat wear sturdy closed toed and heel shoes

Order the steps if vacuum( or suction) filtration

1. place thr Buchner funnel in a sied arm filter flask and attach the filter fask to the hose coming from the vacuum 2. place the unfolded circular filter paper into the funnel and wet it with solvent 3. open the vacuum valve on the fume hood or turn on the vacuum aspirator 4. pour mixture into the funnel 5. use a spatula to transfer solids to the funnel 6. Rinse beaker that contained the mixture and spatula three times, add rinsings to the funnel 7. close vacuum valve or turn off water aspirator before removing hose from the side arm flask

Place the steps listed below for using a Digi-Melt in Order

1. Turn on the Digi-Melt 2. Set starting temperature 3. Set the stop temperature 4. set the rate at which temperature should ramp up 5. add solid to capillary tube 6. Tap solid to bottom of capillary tube 7. place filled capillary into top slots 8. Press start/stop to start heating 9. Watch sample for melting through eye piece 10. record melting range 11. press start/stop to end heating

Order the steps listed below in the proper order for taking an absorbance spectrum

1. prepare a blank by filling a cuvette with solvent 2. wipe outside of blank cuvette with tissue 3. calibrate spectrometer with blank 4. pre-rinse cuvette with a small portion of solution 5. fill cuvette with solution 6. wipe outside of solution cuvette with tissue 7. place cuvette in spectrometer, push play and then stop 8. dilute initial solution if absorbance is too high pr top of spectra is ragged or flatlines at the top. Repeat procedure 9. Attach file to ELN

acute toxicity

ability of a chemical to do damage with a single dose

chronic toxicity

ability of a chemical to do damage after multiple doses

LC 50

lethal concentration that 50% of a population dies

LD50

lethal dose that kills 50% of a population

toxicant

chemical producing toxic effects

toxicity

ability of a chemical to damage an organ

toxicology

study adverse effects of chemicals

toxin

toxic substance made by plant, animal, fungi or bacterium

Which of the following statements are TRUE about the factors influencing toxicity?

animal models may not be a good representation of human response the dose makes the poison the very young and old are most susceptible to toxic effects

Acetaminophen (tylenol) fate in the human body

metabolized and removed by the liver

DDT fate in the human body

bioaccumulation- stored in fat

Ethylene glycol fate in the body

metabolized to calcium oxalate- forms crystals in kidneys

sensitizer?

formaldehyde

asphyxiant?

carbon monoxide

teratogen?

acrylonitrile

carcinogen?

benzene

organ toxiant?

ethanol

neurotoxin?

acetone

poison?

cyanide

If a solid does not melt when placed in a capillary in a Digi-Melt, which of the following assumptions may be true

the Digi-melt doesn't go up to a high enough temperature to melt the solid The digi-melti is broken

there are three TLC plates the 1st one has three spots very close to the solvent front, the second as all three spots equally distance away from each other, the third has all three spots close to the baseline which plate demonstrates the best separation of the mixture

there are three TLC plates the 1st one has three spots very close to the solvent front, the second as all three spots equally distance away from each other, the third has all three spots close to the baseline Which eluent mixture has an intermediate polarity in comparison to the other two mixtures

Which of the following results indicates the product of the synthesis is vanillic acid? Note: The actual result may or may not be vanillic acid.

Rf from TLC is same as vanillic acid TLC from FS solid is soluble in water

KNOW reduction half reaction and oxidation half reaction between vanillin/divanillin and hydrogen peroxide

know that the reduction half reactions are the same but the oxidation half difffers

what is the role of vanillin

limiting reagent

What is the role of acetic acid?

source of H+ for redox balance

What is the role of hydrogen peroxide?

oxidizing agent

What is the role of horeradish peroxidase?

catalyst

A student combined the following and stirred the solution for 10 minutes: 1.031 g of vanillin 2.20 mL 0.010 M acetic acid 9.0 mg horseradish peroxidase 7.5 mL of 3% H2O2 The precipitate which formed was collected by vacuum filtration and dried in the oven. Once the solid reached room temperature it is massed. Answers should have the correct number of significant figures. What is the theoretical yield (in grams) of: vanillin AND divanillin

VA: 1.139 DIV: 1.024

A student combined the following and stirred the solution for 10 minutes: 1.031 g of vanillin 2.20 mL 0.010 M acetic acid 9.0 mg horseradish peroxidase 7.5 mL of 3% H2O2 The precipitate which formed was collected by vacuum filtration and dried in the oven. Once the solid reached room temperature it is massed. If 0.856 g of product is collected, what is the percent yield of:

VA: 75.1% DIV: 83.6%

If the mass of the product is 1.374 g, the product is (more than one answer might be correct): theoretical is (1.139 or 1.024)

wet and needs to be dried further in the oven wet and needs to be dried further in the Buchner funnel more than the theoretical

hazard?

potential source of danger

risk?

probability of suffering harm?

risk level?

hazard severity times exposure limit

risk assesment?

identification of sources of danger and probability of harm

risk management?

wearing personal protective equipment, avoiding spark sources, using smaller amounts

what are the factors that affect the probability of a lab accident?

how chemicals are used? how other people behave? how the physical environment is controlled?

which of the following must be assessed to reduce the probability of expose to a hazard

amount of chemical used, containment of chemicals, personal knowledge of chemicals, routes of exposure, type of personal protective equipment needed

While pouring 1 M of an aqueous potassium permanganate solution from a 1L reagent bottle, a student's hand slipped and the bottle fell and broke open. A small amount of solution splashed onto the student's eyes. The solution also spilled across the bench top and dripped down to create a pool on the floor. a) If no safety precautions are followed the severity of the hazard is:

moderate

possible

medium

While pouring 1 M of an aqueous potassium permanganate solution from a 1L reagent bottle, a student's hand slipped and the bottle fell and broke open. A small amount of solution splashed onto the student's eyes. The solution also spilled across the bench top and dripped down to create a pool on the floor. d) Which measure should be taken to manage the risk?

all of the above ( know what to do if a chemical gets in the eyes, know what to do if spill occurs, wear goggles)

What happens after the crystallization process shown below in the Fundamental Skills section of the cinnamon project? Select all that apply.

the crystals are collected by vacuum filtration the mass and melting point is recorded

What volume (in milliliters) of acetophenone is needed to synthesize a sunscreen with 0.30 mL of cinnamaldehyde?

0.29 mL

What is the theoretical yield (in grams) of the sunscreen created from 0.30 mL of cinnamaldehyde and acetophenone?

0.56

What volume (in milliters) of acetone is needed to synthesize a sunscreen with 0.30 mL of cinnamaldehyde?

0.0876mL

What is the theoretical yield (in grams) of the sunscreen created from 0.30 mL of cinnamaldehyde and acetone?

0.34 g

What is the percent yield is 0.29 g of the sunscreen is collected from the reaction of 0.50 mL of cinnamaldehyde and acetone?

51.1%

Which of the following would help you determine the severity of a hazard?

NFPA fire ratings, GHS symbols, PELs, lethal dose 50 values, chemical amount used

zero risk?

no hazard present

balancing ?

risk allowed increases with benefit of chemical use

technology-based?

exposure level is set to level it can be reduce to

eye hazards?

cause irreversible damage to cornea or iris

sensitizers?

cause hypersensitivity to lungs or skin

mutagens?

produce genetic defects

carcinogens?

cause cancer or presumed to cause cancer in humans

reproductive toxicants ?

cause birth defects

target organ toxicants?

cause damage to certain organs, affecting their ability to carry out normal functions

aspiration hazards?`

can be fatal if swallowed or inhaled

acute toxicants?

are fatal if exposed to the smallest amount

corrosives?

causes serve skin burns and eyes damage

Quiz 4 Session #1 Question 6 MUST MEMORIZE

Heptane and hexane have many similar chemical properties and hexane could be used in place of heptane for the TLC procedure. Why is heptane used for the TLC process instead of hexane? a) hexane has more GHS pictograms b) Hexane is a reproductie toxicant, heptane is not c) hexane has a high vapor below room temperature d) hexane's flash point is at a lower temperature than heptane's e) three of these f) all of these

E) THREE OF THESES

Which of the following characteristics would make a good sunscreen? (select all that apply.)

melting point value, broad absorbance of ultraviolet light ambient reaction conditions (little to no heat or pressure needed) color and feel high percent yield low hazard starting materials

filtration materials?

filtrate vacuum buchner funnel

TLC materials?

eluent, silica plates, solvent front

crystallization materials?

temperature dependent solubility, no agitation

Match the separation process to the type of mixture being separated. Filtration:

heterogeneous mixture

Match the separation process to the type of mixture being separated. TLC:

mixture with components of different polarities

Match the separation process to the type of mixture being separated. Crystallization :

products with impurities

Match the separation process to the project it could be used in: Project #2 (Essential Oil):

TLC

Match the separation process to the project it could be used in: Project #3 (Vanilla):

filtration and TLC

Match the separation process to the project it could be used in: Project #4 (Cinnamon):

filtration, TLC, crystalization

Which of the following statements apply to green chemistry? (Select all that apply.)

methods used to eliminate hazards in during chemical use and manufacturing high yield reactions are desirable recycle reagents and solvents choose reactions that can be done at room temperature and pressure use less hazardous reagents

Which of the following statements about the chemicals or processes in Chem 1LD follow the principles of green chemistry? (Select all that apply.)

use of starting reagents (eugenol, vanillin, cinnamaldehdye) from renewable feedstocks sunscreen synthesis did not require heat

Calculate the atom economy of reaction between cinnamaldehyde and acetophenone in project 2. (See Figure 2). Report your answer with 2 significant figures.

93%