UCI Chem 1LD Practical

What factors determines whether a solute will dissolve in a solvent?

imf's, molecular dipoles, molecular geometry, electrostatic attraction

What is the strongest imf that must be overcome when melting menthol?

hydrogen bonding

A —> solid
B —> liquid and solid
C —> liquid
D —> gas and liquid
E —> gas
F —> boiling point 
G —> melting point

Label A and B. Which direction does each line shift when solute is added?

solid-liquid coexistence line —> A
liquid-gas coexistence line —> B

A shifts left
B shifts right

How do impurities affect melting point? By what colligative property does this occur? 

lower the melting point
freezing point depression

A solution is created when a small amount of solute dissolves in a large amount of _________

solvent

What is concentration of a solvent reported as?

molality or molarity

A solutions concentration is reported in _______ per ________

moles of solute per kilogram of solvent

moles of solute per liters of solution

What should you do to respond to an emergency?

know where the stairwells are
all laboratories must have two exits
stay calm
turn off lab equipment before leaving lab for a fire alarm

True or false: cinnamic acid dissolves in melted menthol

true

True or false: cinnamic acid does not stay dissolved in solid menthol

true

How will a weak acidity affect the freezing point depression?

The solution freezing point is lower than it should be

Why does the freezing point of a solution decrease as a result of weak acidity?

particles in the solution are greater due to dissociation

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

high concentrations

Why is molality used instead of molarity in this project?

volume changes with temperature —> change in molarity

name common household products that contain flammable chemicals

rubbing alcohol, gasoline, antifreeze, nail polish remover

ways to stop a fire

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

what is true about flammability?

1. inflammable is another word for flammable

2. a fire cannot start above or below a vapor's flammability limits

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

best piece of glassware to measure out volumes for TLC eluent ratios is __________

graduated cylinder

polar spots in TLC

are attracted to the silica plate and travel short distances up the plate

non-polar spots in TLC

are attracted to the eluent and travel farther distances up the plate

What is true about fume hoods

room air should be drawn into the fume hood

The window on the front of the fume hood is called a sash.

All work should be done at least 6 inches inside the hood.

A tissue paper held at the bottom of a sash should blow into the hood.

PEL

permissible exposure limit

odor threshold

gas concentration that 50% of the population can detect

odor fatigue

decreased sensitivity to odors over time

IDLH

Immediately Dangerous to Life and Health

OEL

Occupational Exposure Limit

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

what is a stationary phase?

silica TLC plate, likely solid

what is a mobile phase

eluent (heptane/acetone mixture), likely liquid or gas

Why does most of the TLC plate turn pink in permanganate dip?

unreacted permanganate is pink

Why do TLC spots turn yellow after dipping in permanganate?

the compound has double bonds

What is true about gloves?

1. gloves should be removed when they come in contact with any hazardous chemicals

2. no glove material protects against all 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 chemical appears on the other side of the glove

lab coats

sleeves should never be rolled up

should never be worn outside of lab

nitrile gloves

protect well against aliphatic hydrocarbons like heptane and limonene

nitrile gloves can be degraded by acetone (a ketone)

What of the following guidelines should be followed to protect your skin in the chemical laboratory?

1. wear a lab coat

2. wear clothing that covers most of your body

3. wear sturdy closed toed and heel shoes

4. use gloves when appropriate to do so.

toxicology

the study of the adverse effects of chemicals

toxicity

ability of a chemical to damage an organ

toxicant

chemical producing toxic effects

toxin

toxic substance made by plant, animal, fungi, or bacterium (living organisms)

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

LD(50)

lethal dose that kills 50% of a population

LC(50)

lethal concentration that kills 50% of a population

what factors influence toxicity

the dose makes the poison
age —> very young and very old more susceptible to toxic effects
animal models are not always a good representation of human responses

Acetaminophen’s (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 human body

metabolized to calcium oxalate —> forms crystals in kidneys

example of a sensitizer

formaldehyde

example of a asphyxiant

carbon monoxide

example of a teratogen

acrylonitrile

example of a carcinogen

benzene

example of a organ toxicant

ethanol

example of a neurotoxin

acetone

example of a poison

cyanide

what assumptions can be made if the solid does not melt in the digi-melt?

digi-melt does not reach high enough temp to melt the solid or it is broken

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 horseradish peroxidase?

catalyst

hazard

A potential source of danger

risk

probability of suffering harm

risk level

hazard severity x exposure probability

risk assessment

identification of sources of danger and probability of harm

risk management

wearing PPE, avoiding spark sources, using smaller amounts

What affects the probability of a lab accident

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

factors to probability of exposure to a hazard

1. amount of chemicals used

2. type of PPE needed

3. routes of exposure

4. containment of chemicals

5. personal knowledge of the hazards

what determines the severity of a hazard?

1. GHS symbols

2. chemical amount used

3. PELs

4. LD50 values

5. NFPA fire ratings

zero risk

no hazards are present

balancing 

risk allowed increases with benefit of chemical use

technology-based

exposure level is set to level it can be reduced to

eye hazard

causes irreversible damage to cornea or iris

sensitizers

cause hypersensitivity to lungs or skin

mutagens

produce genetic defects

carcinogens

substances that (presumably) cause cancer in humans

reproductive toxins

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 amounts

corrosives

cause severe skin burns and eye damage

what makes good sunscreen

1. high percent yield

2. broad absorbance of uv light

3. low hazard starting materials

4. melting point value

5. ambient reaction conditions (little to not heat or pressure needed)
6. color and feel

filtration terms. what type of mixture is being separated?

filtrate, vacuum, buchner funnel

heterogenous mixture

TLC terms. what type of mixture is being separated?

eluent, silica plates, solvent front

mixture with components of different polarities

crystallization terms. what type of mixture is being separated?

temperature dependent solubility, no agitation

product with impurities

green chemistry

uses materials and processes that are intended to prevent or reduce pollution at its source

what applies to green chemistry

1. high yield reactions

2. methods used to eliminate hazards during chemical use and manufacturing

3. use less hazardous reagents

4. choose reactions that can be done at room temp and pressure

5. recycle reagents and solvents

How does 1LD use green chemistry

using starting reagents from renewable feedstocks

sunscreen synthesis did not require heat

atom economy

MM of product / MM of all reactants * 100