question

Technical bulletin listing physical and chemical properties, hazards, etc of a lab reagent

answer

What is a Material Safety Data Sheet (MSDS) and what data does it usually contain?

question

no eating, drinking, or applying cosmetics in lab.

answer

Define rules about eating, drinking, and applying cosmetics in lab.

question

Sudden release of vapor; use boiling chips

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What does bumping mean and how to avoid it?

question

0 (low) and 4 (high) blue - health red - fire white - specific hazards yellow - reactivity

answer

National Fire Protection Association's Diamond

question

immediately wash off skin with plenty of water, and let TA know.

answer

What to do if spill on skin

question

Use sink or safety shower as necessary. Remove clothing (all). Do not remove safety goggles b/f washing reagent from face (this will lessen the likelihood of getting reagent in eyes).

answer

If spill on person what do you do?

question

Temperature at which solid compound is in equilibrium with its liquid

answer

Define the term: melting point

question

Temperature range between start of liquid formation till all the solid becomes liquid

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Define the term: melting point range

question

Any admixture in the compound of interest

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Define the term: impurity

question

when both solids are in equilibrium with the liquid

answer

Define: eutectic composition

question

the lowest possible melting point for a mixture of X and Y

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Define: eutectic temperature

question

To proof identity of unknown compound: mix known and unknown compounds. If mixture mp is the same as mp of known compound, unknown and known compound are the same

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Describe the purpose and technique of taking mixture m.p.

question

Decomposition

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Explain the phenomena (name the process): compound to melt is darkening when heating and release gas when melting

question

Sublimation

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Explain the phenomena (name the process): compound disappears from capillary when attempting to measure its m.p.

question

if mp is unknown then first measure the approximate melting point of the compound. Then you let appratus cool to 15 degrees below the orientation mp; new sample is heated increasing the temp at 1-2 degrees Celsius per minute to get the accurate mp.

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Define: orientation mp

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1) placement of too much sample into the capillary tube (poor heat transfer) - should be 2-3 mg 2) not grinding particles (poor heat transfer)

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Errors in observed mp

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droplets on outside surface of sample, due to insufficient drying

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define: sweating

question

darkening in the color of the compound as it melts

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define: decompose

question

passes directly from solid to vapor, the compound disappears - sample vaporizes and recrystallizes higher up in capillary tube

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define: sublimation

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1) F 2) F 3) T

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In distillation Term volatile is related to a chemical having (true or false): 1) Low pressure at high temperature 2) High pressure at high temperature 3) High pressure at low temperature

question

technique used for separating compounds based on differences in their bp

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Define: distillation

question

Macro

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Distillation was made using 15 mL of each cyclohexane and toluene. With what scale:

question

where volatile compounds are heated to boiling in one container

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define: pot

question

where the vapors that are produced are then cooled and re-liquefied by passing them through a water cooled condenser

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define: condenser (explain how used)

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where the re-liquified cooled produces are collected

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define: receiver

question

transition from liquid to vapor on only those molecules at the liquid surface (happens at temp below the bp of compound)

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define: evaporation

question

pressure exerted by these gaseous molecules on the walls of the container

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define equilibrium vapor pressure:

question

Temperature, at which vapor pressure of liquid equals external pressure

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Define: boiling point

question

liquids mix

answer

define: miscible

question

Rault's Law

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Distillation of miscible liquids best described using:

question

PT = P1X1 + P2X2 PT - total pressure P1,2 - partial pressure X1,2 - molar fraction of component

answer

Write the equation for Rault's law and define the terms

question

when the vapors condense into a liquid, and have the same composition as the vapors formed

answer

Define: distillate

question

if one compound is much more volatile than the other

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Define: simple distillation

question

it has a fractionating column between the pot and distilling head

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What makes fractional distillation different from simple distillation?

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True

answer

True or False: Vapors over the mixture of cyclohexane and toluene contain the higher percentage of cyclohexane than that in mixture

question

1) false 2) false 3) true

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B.p. of mixture of 2 liquids is always (T or F) 1) Lower than b.p. of both components 2) Higher than b.p. of both components 3) In between the b.ps. of both components

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True

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True or False: Fractional distillation is preferable if difference in b.p. of mixture components is lower than 40 degrees C

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Do not distil to dryness Do not heat closed system

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State two rules not to break when performing distillation

question

purification process used to remove impurities from organic compounds that are solid at room temp

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Define: recrystallization

question

when a compound is insoluble in a solution at a temp above the compound's mp. As a result the compound is deposited as an oil, and not crystals

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Define: oiling out

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room temp: insoluble bp: soluble ice: insoulble

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How to choose a good solvent

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two solvents are used to dissolve compound

answer

Define: solvent pair

question

flask with a sidearm

answer

define: filter flask

question

(mass of recrystallized compound in g / mass of crude compound in g) (100%)

answer

equation for percent recovery

question

it melts at a range of 1-3 degrees Celsius near its reported melting point

answer

How to tell is compound is pure

question

1) scratch glass to give crystals sites to form 2) put seed crystal of pure compound into the soln

answer

If crystals don't form what can you do?

question

add activated carbon

answer

If solution has colored impurities

question

heat funnel, filter paper, and collection flask

answer

How to avoid premature crystallization in the funnel stem

question

a solvent used as a mobile phase

answer

Define: eluent

question

thin layer chromatography

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TLC

question

distance traveled by comp, mm / distance traveled by solvent, mm

answer

Equation for Rf

question

the point that the eluent has reached

answer

define: eluent front

question

the greater its eluting power, ability to move compounds over the absorbent surface

answer

the more polar the eluent

question

Injector, column, detector

answer

Name 3 main parts of Gas Chromatograph

question

Area peaks

answer

Chromatogram after analysis of some mixture shows several peaks. Ratio of components in the mixture is proportional to:

question

toluene or ethyl ether

answer

What solvent was suitable for separation of 2 polar compounds using silica gel:

question

Under UV-light or in iodine chamber

answer

State 2 methods of visualizing TLC plates

question

(mass of recovered compound / mass of compound in original mixture) (100%)

answer

Write the equation for the % recovery in column chromatography

question

1+1+3 = 5 parts total; 170mg/5parts = 34mg [1 part] of each ferrocene and acetylferrocene; 34x3[parts]=102mg of alumina

answer

Calculate the mass of components in 170 mg of 1:1:3 mixture (by mass) of ferrocene, acetylferrocene and alumina

question

Air bubbles will form in sorbent bed. Those bubbles may prevent solvent from moving through bed, and mixture to separate

answer

Describe the consequences of column dry-out during a separation

question

process that selectively dissolves one or more of the mixture compounds into an appropriate solvent

answer

Define: Extraction

question

reverse process of extraction, in which the impurities are removed to the second solvent, leaving the desired compound in the original solvent

answer

define: washing

question

suspension of small droplets of one liquid into another liquid

answer

define: emulsion

question

Immiscible

answer

Codistillation (including steam distillation) is possible if components of mixture are:

question

Distillation of compound at lower temperature lower risk of thermal decomposition

answer

State why Steam distillation is preferable for compound that boils at high temperature (>250 C at 1atm)

question

eugenol eugenole acetate

answer

Clove oil components are:

question

eugenol on the -OH group

answer

Will eugenol or eugenol acetate react with sodium hydroxide? What functional group will the reaction occur at?

question

Dalton's Law

answer

When two liquids are immiscible the equation used is?

question

acetanilide - none t-butylphenol - NaOH p-Toluic acid - NaHCO3

answer

Match the compounds and reagents used to separate mixture by extraction: acetanilide NaOH t-butylphenol none p-Toluic acid NaHCO3

question

Turn separatory funnel upside down and carefully open stopcock

answer

Describe how properly release pressure buildup in separatory flask during the extraction

question

If 1 mole of each component, mass of mixture will be 135+150+136=421g 4.3g of mixture will correspond to 4.3/421=0.0102mole of each component Starting amounts: Acetanilide, g = 0.0102mole x 135g/mole = 1.37g; t-Butylphenol, g = 0.0102mole x 150g/mole = 1.53g; p-Toluic acid, g = 0.0102mole x 136g/mole = 1.36g %recovery acetanilide = (1.0g/1.37g)x100% = 73% %recovery t-butylphenol = (1.0g/1.53g)x100% = 65% %recovery p-tolic acid = (1.0g/1.36g)x100% = 74%

answer

Calculate % recovery of each component if 1.0 g each acetanilide, t-butylphenol and p-toluic acid isolated from 4.3 g of 1:1:1 mixture (molar ratio) acetanilide MW = 135 g/mol t-butylphenol MW = 150 g/mol p-toluic acid MW = 136 g/mol

question

right is R Left is S

answer

Sterochemistry

question

No

answer

Assuming solvolysis of 2-chloro-2-methylpropane proceeds as SN1 reaction, does rate of reaction depends on NaOH concentration?

Organic Chem 1 Lab Midterm – Flashcards

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