Question

Write the physical and chemical properties of carbon dioxide.

Answer 1

Physical properties of carbon dioxide

Nature:

• Carbon dioxide is a colourless, odourless, and non-poisonous gas.
• But excess carbon dioxide can cause suffocation.
• A person may die due to a lack of oxygen.

Density:

• Carbon dioxide is 1.5 times heavier than air.

Solubility:

• Carbon dioxide is fairly soluble in water at ordinary pressure.
• Aquatic plants prepare their food by using carbon dioxide dissolved in water.

Liquefaction and solidification:

• Carbon dioxide can be liquefied at room temperature by applying high pressure.
• When this liquid carbon dioxide is cooled at -78°C, it leads to the formation of solid dry ice.
• Dry ice is used in refrigeration of food items to keep them cold because it sublimes instead of turning to liquid and hence does not wet food items.

Chemical properties of carbon dioxide

Combustibility:

• Carbon dioxide is neither combustible nor a supporter of combustion.
• However, some metals like sodium, potassium and magnesium continue to burn in carbon dioxide, forming black specks of carbon.

Action with litmus paper:

• When a moist blue litmus paper is introduced in a gas jar full of carbon dioxide, the litmus paper turns red.
• This shows that the gas is acidic in nature.

Action with water:

• Carbon dioxide is an acidic gas. It dissolves in water to form a weak acid called carbonic acid.

$$\begin{gathered} {\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{H}}_2{\mathrm{CO}}_3\left(\mathrm{g}\right) \\ \mathrm{Carbon}\mathrm{dioxide}\mathrm{Water}\mathrm{Carbonic}\mathrm{acid} \end{gathered}$$

Action with alkali:

• Carbon dioxide is acidic in nature so it is easily absorbed by alkali. In this process, a salt and water are produced.
• Bicarbonate salts are produced when excess of carbon dioxide is used.

$$\begin{gathered} 2\mathrm{NaOH}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)\to {\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O} \\ \mathrm{Sodium}\mathrm{hydroxide}\mathrm{Carbon}\mathrm{dioxide}\mathrm{Sodium}\mathrm{carbonate}\mathrm{Water} \\ {\mathrm{Na}}_2{\mathrm{CO}}_3\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 2{\mathrm{NaHCO}}_3\left(\mathrm{s}\right) \\ \mathrm{Sodium}\mathrm{carbonate}\mathrm{Carbon}\mathrm{dioxide}\mathrm{Water}\mathrm{Sodium}\mathrm{bicarbonate} \end{gathered}$$