Tech 1: Purification and Characterization of Organic Liquid

Question 1

What is the colligative property of contaminated solids and liquids?

Answer 1

for solids, contaminations will lead to lowering and broadening of its melting point (boiling point)

for contaminated liquids, their boiling points may be elevated but it can also be lower

Question 2

What is simple distillation?

Answer 2

this is a method to separate either a liquid from a dissolved solid, or two liquids that differ in boiling points by over 100c

Question 3

What is fractional distillation?

Answer 3

a method for operating liquids that typically differ in boiling points less than 100c

Question 4

What is steam distillation?

Answer 4

a method for separating a water insoluble compound using steam

Question 5

What are the two reasons one would typically preform a distillation?

Answer 5

1. It is a method for quickly removing a solvent to either leave behind in the distillation flask a non-volatile solid, or to concentrate a solution.
2. a distillation can be used to purify a volatile liquid since the components distill according to boiling point.

Question 6

What is an azeotrope?

Answer 6

a liquid mixture with constant boiling point.

Question 7

What is spectroscopy?

Answer 7

Spectroscopy is the study of how matter interacts with electromagnetic radiation.

Question 8

What is IR spectroscopy?

Answer 8

A technique for measuring how much infrared radiation is absorbed by a particular sample.

Question 9

What bond is this (C=O) and what is the absorption range?

Answer 9

carbonyl. 1600-1800 cm-1

Question 10

What bonds are these (NH) and (OH) and what is the absorption range?

Answer 10

amine and hydroxyl. 3100-3500cm-1

Question 11

What is the thin/neat film method? What is the problem with this method?

Answer 11

A sample is sandwiched between NaCl plates. If the sample is a pure liquid then this technique is known as “neat” or “thin film”

One of the most common problems with the thin film technique is application of too much sample which leads to a heavy absorbed spectrum.
Or too little sample will give weak peaks.

Question 12

What is KBr pellet method?

Answer 12

A sample is ground up with KBr and compressed into a clear pellet

Question 13

What is the Nujol mull method?

Answer 13

If the sample is a solid, then it must be made transparent and this is usually accomplished by dissolving the sample in a mull.

Question 14

What is the ATR method?

Answer 14

ATR works by crushing a sample of the analyze on a diamond surface so that there is intimate contact.