OCHEM LAB 1 MIDTERM PRACTICAL

Question 1

Obj: To purify compounds that are _> 90% pure

Answer 1

Recrystallization is the process

Question 2

Key Steps:
1. Dissolve 2g solid in ethanol on a hotplate (100 C)
2. Gravity filter and cool filtrate in fume hood
3. Add DI H2O to crash out the solid
4. Ice bath with 10ml of 50% v/v EtOH in DI H2O
5. Vacuum filter and wash with solution, dry crystal on lamp

Answer 2

Recrystallization is the process

Question 3

Cleanup:
1. discard filter paper, capillaries, and solid waste
2. Rise glassware with ethanol, into aqueous organic waste container

Answer 3

Recrystallization is the process

Question 4

Obj: To separate two liquid based on their boiling points

Answer 4

Distillation is the process

Question 5

Boiling point difference is _> 40 C

Answer 5

simple distillation

Question 6

Boiling point difference is < 40 C

Answer 6

fractional distillation

Question 7

Key Steps:
1. Assemble distillation apparatus
2. Heat mantle 165C simple, 180C fractional distillation
3. Collect distillate in 10 mL increments
4. Turn in GC Analysis immediately after (discard #2)

Answer 7

Distillation is the process

Question 8

Cleanup:
1. Gas Chromatograms and percent composition
2. Plot temp vs volume

Answer 8

Distillation is the process

Question 9

Required Data:
1. Record Melting Point
2. Calculate Percent Recovery
%recovery = (recovered mass/ initial mass)*100

Answer 9

Recrystallization is the process

Question 10

Clean up:
1. Disassemble glassware and wipe off vacuum grease and rinse with acetone in organic waste
2. Discard fractions and vials into appropriate waste containers

Answer 10

Distillation is the process

Question 11

% composition

Answer 11

= (component peak area / total peak area) * 100

Question 12

Obj: To separate a two-component mixture using NaOH

Answer 12

Base extraction is the process

Question 13

Two component mixture

Answer 13

Once acidic and one neutral

Question 14

Key Steps:
1. Dissolve 2g of your solid in 30ml of diethyl ether and in separatory funnel
2. Extract (2x) with 15mL of 10% w/v NaOH, place in base extract beaker
3. Pour organic into beaker, add 1-2 scoop of sodium sulfate, and decant (transfer liquid only), then evaporate in 20/40 roundbottom flask
4. Neutralize with 3M HCl , base extract should precipitate, check acidity, ice bath with 10ml DI H2O in separate beaker.
5. Vacuum filter, wash with cold DI H2O
6. Scrape and place in watch glass to dry (weigh watch glass before), weigh crystals after dried
7. find MP

Answer 14

Base Extraction is the process

Question 15

Clean up:
1. Solid Chemicals into solid waste
2. Buchner Flask into aqueous waste
3. Leftover Sodium Sulfate rinse with DI H2O and into aqueous waste
4. Separatory funnel rinse with soap & DI H2O
5. Clean other glassware with acetone in organic waste
6. MP capillaries into broken glass container

Answer 15

Base Extraction is the process

Question 16

Required Data:
1. MP range for solids
2. Precent recovery (0.5*starting mass)
3. Don’t fall for spectator ions (Cl- or Na+)

Answer 16

Base Extraction is the process