Organic Analysis

Question 1

What is the fingerprint region in infrared spectroscopy?

Answer 1

A region under 1500 wave numbers.

Question 2

If a compound dissolves in water, what does it suggest about its polarity?

Answer 2

It is a polar group.

Question 3

How do you test for an Alkene?

Answer 3

Shake sample with bromine water.

Question 4

What is the positive and negative result of a chemical test for Alkenes?

Answer 4

P - orange colour disappears

N - remains orange

Question 5

How do you test for a halogenoalkane?

Answer 5

1) Add NaOH(aq) and heat
2) Acidify with HNO3
3) Add AgNO3(aq)

Question 6

What is the positive result of a halogenoalkane chemical test?

Answer 6

Precipitate of Silver halogen

Question 7

How do you test for an alcohol?

Answer 7

Add acidified K2Cr2O7.

Question 8

What is the positive and negative result of a chemical test for alcohol?

Answer 8

Positive - orange colour turns green with primary or secondary alcohol (and aldehydes).
Negative - orange

Question 9

How do you test for an aldehyde?

Answer 9

Warm with Fehling’s solution or Tollens’ solution.

Question 10

What is the positive result for Fehling’s test?

Answer 10

Blue colour turns to red ppt

Question 11

What is the positive result for Tollens’ test?

Answer 11

Silver mirror forms

Question 12

What is the chemical test to detect carboxylic acids?

Answer 12

Add NaHCO3(aq)

Question 13

What is the positive result of the chemical test for carboxylic acids?

Answer 13

CO2 is produced

Question 14

How do you test for an alkene (C=C)?

Answer 14

Shake with bromine water
Positive - clear
Negative - stays orange

Question 15

How do you test for a halogenoalkane (R-X)?

Answer 15

1) add Sodium Hydroxide (aq) and warm solution
2) acidify with nitric acid (HNO3)
3) add silver nitrate (aq)

Question 16

What the positive result of a halogenoalkane test?

Answer 16

Precipitate of AgX (Cl, Br, I)

Nothing (F)

Question 17

How do you test for an alcohol?

Answer 17

Add acidified potassium dichromate.

Question 18

What the positive result of an alcohol test?

Answer 18

Orange colour turns green with primary and secondary alcohols and with aldehydes.

Question 19

How do you test for aldehydes? (R-CHO)

Answer 19

Warm with Fehling’s solution

or

Warm with Tollens’ solution

Question 20

What’s the positive result for an aldehyde test?

Answer 20

Fehling’s - blue colour turns to red precipitate

Tollens’ - silver mirror forms

Question 21

How do you test for carboxylic acids? (R-COOH)

Answer 21

Add sodium hydrocarbonate (NaHCO3(aq))

Question 22

What’s the positive result for a test for carboxylic acids?

Answer 22

CO2 is given off.