(Chapter 16.6) Carbon and its compounds by: Clifford Herbert Theodore Class: 3V

Introduction
Carbon is an element which is of immense significance to us in both its elemental form and in the combined form. Most of what surround you will some compounds of carbon, including your family members and pets.

The importance of carbon compounds in our daily life:

• Foods [e.g starch, sugar, fats, vitamins, proteins]
• Fuels [e.g wood, coal, alcohol, petrol]
• Household and commercial articles [e.g paper, soap, cosmetics, oils, paints]
• Textile fabrics [e.g cotton, wool, silk, nylon]
• Drugs
  
• Poisons
  
• Perfumes
  
• Explosives
  
• Dyes
  
• War gases

Properties of Carbon Dioxide

1. Physical Properties
(a) Nature
- Carbon dioxide is a colourless and odourless gas very slightly sour in taste.

(b) Density
- Carbon dioxide is heavier than air. Its density is 22 (Density of air = 14.4). Hence, it tends to move downwards.

(c) Solubility
- It is only barely soluble in water. The solubility of carbon dioxide can be greatly increased by increasing the pressure and by lowering the temperature. (e.g A well chilled open bottle of soda water can retain more carbon dioxide for a long time than an open one at ordinary temperature.)

2. Chemical Properties
(a) Nature
- Carbon dioxide is slightly acidic.

(b) Stability
- Carbon Dioxide is a very stable gas at ordinary temperature and pressure.

(c) Combustibility
- Carbon dioxide does not support combustion as things will not burn in it.

3. Reaction with water

- Carbon dioxide dissolves in water only to a very small extent. This small quantity of the gas combines with the water to form carbonic acid.


Carbon can be classified into two categories:

1. Inorganic compounds
- Carbon compounds with those elements having their origin in minerals, such as oxygen and metals are called inorganic compounds. Inorganic compounds of carbon do not have carbon-carbon bonds.

2. Organic Compounds
- The compounds of carbon generally containing carbon-carbon bonds are called organic compounds. These occur in carbon compounds with hydrogen and their derivatives. Examples of organic compound: ethyl alcohol, sugar, starch.

Test for Carbon Dioxide using lime water

1. Add about 2ml of Hydrochloric acid

2. Add 1 spatula of a carbonate to the acid, stopper the test tube

3. Pour about 2ml of lime water (calcium hydroxide) to a test tube and delivery tube

4. Stopper end goes to the test tube of HCL and carbonate

5. Shake to bubble gas into lime water

6. Warm gently, moving side to side at the tip of the flame(where it is not too hot)

7. White precipitate will be formed.


Here is a video to illustrate the test for Carbon Dioxide using lime water
http://www.youtube.com/watch?v=21aBA0jUJXU


Thank You For Your Attention!! :)