BP Diagrams and Azeotropes

# BP Diagrams and Azeotropes - (Temperature-composition...

This preview shows pages 1–9. Sign up to view the full content.

Some “dissolving” involves chemical reactions. .. Reaction of ester with base (KOH or NaOH) to form alcohol (e.g., glycerol) and fatty acid salt (“soap”). (triglyceride) Ammonia cleaning action: NH 3 + H 2 O NH 4 + + OH - Cleaning up grease with ammonia: Saponificaton Note surfactant character C-C-C-C-C-C-C-C-C-C-C-C-C-C-C O Just something of interest for you

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
What we know about binary solutions of volatile substances Raoult’s Law of ideal solutions allow us to predict partial pressures (and total pressure) at a given temperature if we know P o Non-ideal solutions cause positive or negative deviation of what is predicted by Raoult’s Law We cannot predict when a solution will boil (i.e., at what temperature the total pressure is 1 atm) X A 0 1 Press P o A P o B P Tot P o B X A 0 1 P o A P Tot
What we need is information on the boiling point (T b ) as a function of mole fraction (e.g., X A )... and… the composition of the vapor above the boiling liquid ? X A 0 1 T b

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Boiling point diagram

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: (Temperature-composition diagram) X A 1 T b ( o C) X A (vapor) X A (sol’n) Sol’n composition Vapor composition Consider a solution where X A = 0.75 … Solution boils at 92 … and vapor composition is 0.35 92 0.35 150 50 Vapor (distillate) getting richer in more volatile benzene, but “pot” getting richer in less volatile toluene A B C D D THE EXPERIMENT Fractional distillation 20 40 60 80 100 120 140 0.2 0.4 0.6 0.8 1 X A boiling temperature ( o C) Minimum boiling azeotrope Original composition of pot Composition of the “distillate” moves toward fixed composition Maximum boiling azeotrope Composition of the “pot” moves toward fixed composition Colligative properties (depends on “ number of particles ”, expressed as molality ) • Boiling point elevation • Freezing point depression • Osmotic pressure...
View Full Document

{[ snackBarMessage ]}

### Page1 / 9

BP Diagrams and Azeotropes - (Temperature-composition...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online