CH 220C Quiz 2

SOPs

C: Disposing of waste

D: Wearing gloves

E: Using acids and bases

F: Pressure

G: Using organic chemicals

H: Glassware

I: Heating reactions

MSDS Acids

2-Chlorobenzoic acid

2-Methylbenzoic acid

Benzoic acid

Salicylic acid

MSDS Bases

3-Methyl-4-Nitroaniline

3-Nitroaniline

4-Nitroaniline

MSDS Neutrals

9-Fluorenone

Anthracene

Fluorene

Phenanthrene

MSDS Solids and Solvents

Ethyl Acetate

1M NaOH

1M HCl

Sodium Sulfate

Hazard Analysis: Ethyl Acetate

Danger: Splash into eyes

Symptoms: Irritation, redness, pain, and lacrimation (tears)

Avoid: Must wear safety goggles

What to do: Thoroughly flush eyes with water for several minutes, removing contact lenses if possible, and seek medical advice.

Hazard Analysis: Separatory Funnel

Danger: Leaking 1 M HCl from stopcock

Symptoms: Severe irritation, inflammation, ulceration, necrosis, chemical burns, shock, rapid pulse, sweating, and collapse.

Avoid: Protective gloves and clothing. Properly seal funnel.

What to Do: Remove contaminated clothes/jewelry, thoroughly wash skin with 5% aqueous sodium bicarbonate, soap and water, and seek medical advice.

Hazard Analysis: 1M NaOH

Danger: Transferring it from stockroom bottle to a beaker not wearing gloves
Symptoms: Redness, cutaneous burns, and skin fissures.
Avoid: Protective gloves and clothing.
What to Do: Remove contaminated clothes/jewelry, thoroughly wash skin with soap and water, and seek medical advice.

Hazard Analysis: 4-Nitroaniline

Danger: Accidental inhalation
Symptoms: Headache, unconsciousness, coughing, chest pains, difficulty breathing and vomiting
Avoid: Ventilation, local exhaust.
What to Do: Remove from exposure immediately and seek medical advice.

Why must the separatory funnel be vented?

To relieve the pressure that builds up upon shaking.

What should you do if you spill HCl or NaOH on your skin?

Rinse the affected area with running water for at least 15 minutes.

In the recrystallization step, what size crystals are we looking for?

Not too large and not too small.

In regards to recrystallization, what is seeding?

The addition of a small amount of the pure, crystalline compound to a saturated solution of the compound.

What is the ratio of base, acid, and neutral in the experimental mixture?

1:1:1

What is the basis of separation in extraction?

Solubility

What affects solubility?

1. Temperature
2. Pressure
3. pH
4. Ionic strength

Rules for extraction

1. Sx and So are immiscible
2. Sx must have low b.p.
3. Extraction compound must be soluble in Sx
4. Sx cannot react irreversibly with extraction compound
4. Ionic strength

Benzoic acid + NaOH

H2O insoluble
Org. soluble

Sodium benzoate + Water

H2O soluble
Org. insoluble

Sodium benzoate + HCl

Benzoic acid (s) + NaCl

Ions are more soluble in

H2O

Neutral molecules are more soluble in

Organic solvent

Recrystallization is a method of _

Purification

Recrystallization depends on difference in between pure compound and impurity

Solubility

Recrystallization solvent should be chosen such that pure compounds are ____ at room temperature and ____ at high temperature

insoluble, soluble

Impurities should be soluble at ___ temperature in recrystallization

any

What glassware do we use?

Separatory funnel, Erlenmeyer flask

How do we prevent the separatory funnel from leaking?

Add small portion of water
Tighten nut if it still leaks
Drain water

Which layer will drain from separatory funnel first?

Aqueous layer

What will let you know that gas is being released from the separatory funnel?

Hissing sound

What should you do if the methanol boils too vigorously?

Turn hotplate down. Move beaker to edge where the hotplate is cooler.

What should you do if the solvent begins to boil but there is still undissolved solid?

Add a pipette of hot methanol

What should you do if you do not collect a sample after precipitation?

Continue with what you were able to recover or ask your TA if you can be paired with another student.

What should you do if the base does not precipitate?

Try blowing air over the top of the solutions.

What must you do before draining the separatory funnel?

Remove the glass stopper

What is the procedure for Mel-Temp analysis?

Carefully load small amounts of crystals to capillary tubes; about 3 mm of sample per tube. Then watch through the eye-piece as the temperature increases.

How should you determine the starting temperature for Mel-Temp analysis?

The melting points of the crystals are known, so starting temperature should be near m.p. To prevent temperature from increasing at a rate higher than 2°C per minute.

Which solvent is So?

Ethyl Acetate

Which solvent is Sx?

HCl

What do we accomplish by shaking the separatory funnel?

Maximizes surface area

Why should we avoid shaking the separatory funnel too gently?

This will not maximize surface area

Why should we avoid shaking the separatory funnel too hard?

This will introduce too much air to the mixture

Which solvent will extract base (B)?

HCl

Which solvent will extract neutral (N)?

Ethyl Acetate

Why do we cool NaOH/HCl mixture?

Neutralization is exothermic

What should we do with the air hose before running it over the HCl/B solution?

Run for 5 minutes to clear out water

What purpose does Na2SO4 serve?

Drying agent that absorbs Ethyl Acetate

Ethyl acetate has ___ vapor pressure

high