Experiment 1: Composition of Most Organic Compounds (compiled)

Question 1

What is Experiment 1 called?

Answer 1

Composition of Most Organic Compounds

Question 2

Purpose of the experiment:

Answer 2

To detect the presence of chief elements in organic compounds

Question 3

A1. Carbon & Hydrogen procedure:

Answer 3

Materials

1. Dry egg albumin

Procedure

1. Heat a very small amount of dry egg albumin in a test tube.
2. Continue heating until there is not further change.

Question 4

A2. What collects in the upper and cooler portion of the test tube?

Answer 4

Water forms in the upper portion

Charred albumin particles form in the lower portion

Question 5

A3. Organic compounds are frequently _____; instead, they char

Answer 5

Inflammable

Question 6

A4. Formation of water in upper portion of test tube indicates presence of _____

Answer 6

Hydrogen

Question 7

A5. How did the water form?

Answer 7

• When the albumin was heated, the hydrogen was stripped off the albumin’s chemical bonds
• After being stripped off, it was exposed to the oxygen in the atmosphere

Question 8

A6. This occurs when organic compounds are burnt and breaks a molecule’s chemical bonds.

Answer 8

Thermal Decomposition

Question 9

A7. Charring indicates the presence of _____

Answer 9

Carbon

Carbon condenses into char

Question 10

B1. Nitrogen test:

Answer 10

Materials

1. CH4N2O / urea
2. CaHNaO2 / soda lime
3. Red litmus paper

Procedure

1. Mix together 1/2 grams of CH4N2O and 1 gram of CaHNaO2 with a mortar and pestle.
2. Pour the mixture into a dry test tube and heat gently.
3. Hold a piece of red litmus paper at the mouth of the test tube.

Question 11

B2. What was the odor of the gas evolved?

Answer 11

Urine-like

Question 12

B3. What gas was evolved after heating CH4N2O with CaOH NaO?

Answer 12

NH3 or Ammonia

Question 13

B4. How was Ammonia (NH3) formed?

Answer 13

Heating Nitrogen-containing organic compounds with CaHNaO2 / soda lime removes their amino acids, therefore evolving into NH3

Question 14

B5. Why did the red litmus paper turn blue?

Answer 14

It was exposed to a basic substance, which was NH3 in this case

It would have remained if exposed to acid or neutral substances

Question 15

B.6 Nitrogen test formula:

Answer 15

CH4N2O (urea) + NaOH CaO (soda lime) = NH3 (ammonia)

Question 16

C1. What is the test for detecting Sulfur called?

Answer 16

Lead Acetate test

Question 17

C2. Sulfur / Lead-acetate test:

Answer 17

Materials

1. NaOH or sodium hydroxide
2. Dry egg albumin
3. Pb (C2H3O2)2 or lead acetate

Procedure

1. Pour 2 mL dilute NaOH and dry egg albumin into a test tube.
2. Heat for a minute or more, then cool test tube in running water.
3. Add a few drops of Pb (C2H3O2)2.

Question 18

C3. What happens when egg albumin and NaOH mix?

Answer 18

The sulfur from the albumin and NaOH form Sodium sulfide or Na2S

Question 19

C4. Sodium sulfide formula:

Answer 19

NaOH + albumin -> Na2S (sodium sulfide)

Question 20

C5. What happens when Pb (C2H3O2)2 drops are added to Na2S solution?

Answer 20

The sulfuric amino acids in Na2S react with Pb (C2H3O2)2 and form PbS or lead sulfide

Question 21

C6. PbS formula:

Answer 21

Na2S + Pb (C2H3O2)2 = PbS + 2NaC2H3O2

Question 22

C7. What is the physical result of PbS which indicates presence of Sulfur?

Answer 22

Black precipitate

Question 23

D1. Test for detecting Phosphorous

Answer 23

Ammonium Molybdate Test

Question 24

D2. Phosphorous / Ammonium Molybdate test:

Answer 24

Materials

1. Albumin
2. HNO3 or Nitric acid
3. (NH4)2 MoO4 or Ammonium molybdate

Procedure

1. Pour a small amount of albumin and 1 mL HNO3 in test tube.
2. Boil carefully until solution becomes clear.
3. Cool thoroughly, and then add an equal amount of cold water in test tube.
4. Add a small amount of (NH4)2 MoO4 solution and warm carefully.

Question 25

D3. What happened after albumin interacted HNO3?

Answer 25

• Phosphorous in the albumin fused with HNO3 and oxidized to PO4^-3 or phosphate

Question 26

D4. What was formed after PO4^-3 interacted with (NH4)2 MoO4?

Answer 26

Ammonium phosphomolybdate or (NH4)3 PO4 * 12MoO3

Question 27

D5. Indicates presence of (NH4)3 PO4 * 12MoO3:

Answer 27

Yellow precipitate

Question 28

E1. What is the name of the test for detecting halogens?

Answer 28

Beilstein test / Flame test

Question 29

E2. Halogens test:

Answer 29

Materials

1. Cu wire
2. CHCl3 / chloroform

Procedure

1. Heat Cu wire in hottest portion of the flame until it doesn’t give any color to the flame. Allow to cool.
2. Moisten wire with CHCl3 in test tube.
3. Hold the wire again in the flame.

Question 30

E3. A _____ was produced when Cu wire moistened with CHCl3 was heated

Answer 30

Green flame

Question 31

E4. How does Chlorine affect Cu wire?

Answer 31

• Chlorine in CHCl3 reacts with the wire’s CuO (copper oxide)
• This produced copper-halide compounds,specifically CuCl2

Question 32

E5. What happened to copper-halide once wire was exposed to flame a second time?

Answer 32

Copper-halide decomposes