Lab 3: Fractional and Simple Distillation of an Unknown Liquid

If the distillation rate of uneven (spurting), you should...

adjust heat to maintain steady boiling

If you keep distilling a mixture long enough, the pot composition becomes...

more high-boiling

Overfilling a distillation flask increases risk of...

bumping and carryover (splashing into head)

When using a vacuum pump, you should always...

check glassware for cracks/chips

The cooling water should be adjusted so it...

flows steadily without spraying off tubing

A good time to switch receivers is when...

temperature begins to rise toward a new plateau

The thermometer bulb should be positioned...

at the level of the sidearm entrance (vapour path)

If no distillate is coming over but pot is still boiling, a likely cause is...

Thermometer placed wrong or condenser blocked/leaking

Heating mantles should be kept dry because...

Liquid can cause electrical hazard

The best distillation rate (typical simple/fractional at atmospheric pressure) is often...

1-2 drops/sec

Why should the apparatus be allowed to cool before disassembly?

Prevent burns and reduce pressure/vapour hazards

If your boiling chips stop working (no smooth boiling), you can...

Use stirring or allow cooling before adding new chips

Fractional distillation is particularly useful for...

two miscible liquids with similar boiling points

If you want higher purity for close-boiling liquids, you should...

use fractional distillation and slow rate

A properly functioning condenser will feel...

Cooler toward the bottom where water enters

A properly running distillation of a pure compound, the head temperature should...

Remain nearly constant at the boiling point

If distillate is coming over but temperature reading is unstable, likely cause is...

Distillation rate too fast or or poor thermometer placement

A common way to reduce bumping is to add...

boiling chips or stir bar

Why should you add boiling chips before heating?

Safer, smoother boiling

When should simple distillation be used instead of fractional distillation?

When the boiling point difference between compounds is 110 C or more