Carbon(IV) Oxide and Trioxocarbonate (IV) Salts | Chemistry for JAMB PDF Download

Carbon(IV) Oxide (CO₂) - Laboratory Preparation, Properties, and Uses

Laboratory Preparation

Properties

• Carbon(IV) oxide is a colorless, odorless gas at room temperature.
• It is slightly denser than air and does not support combustion.
• It is soluble in water, forming carbonic acid (H₂CO₃).

2. Chemical Properties

• Carbon(IV) oxide is a weak acid and reacts with water to form carbonic acid, which can undergo further decomposition to produce hydrogen ions (H⁺) and carbonate ions (CO₃^2-).
• It can react with certain metal oxides, such as magnesium oxide, to form metal carbonates.
• Under high pressure and low temperature, carbon(IV) oxide can be converted into a solid (dry ice) without passing through the liquid phase.

Uses

• Carbon(IV) oxide is widely used in the food and beverage industry for carbonation in soft drinks and sparkling water.
• It is used in fire extinguishers as it displaces oxygen, thereby smothering the fire.
• In the medical field, it is used during laparoscopic surgery to inflate the abdominal cavity.
• Carbon(IV) oxide is also employed in various industrial processes, such as oil recovery, chemical synthesis, and pH regulation.

Action of Heat on Trioxocarbonate (IV) Salts

When trioxocarbonate (IV) salts, commonly known as carbonates, are heated, they undergo thermal decomposition to produce carbon(IV) oxide and a metal oxide. The reaction can be represented by the following equation:
Metal Carbonate → Metal Oxide + Carbon(IV) Oxide
For example, when calcium carbonate (CaCO₃) is heated, it decomposes to form calcium oxide (CaO) and carbon(IV) oxide:
CaCO₃(s) → CaO(s) + CO₂(g)
This reaction is often used in industries to obtain carbon(IV) oxide and metal oxides, which have various applications.

Test for CO₃^2- (Carbonate) Ion

To test for the presence of the carbonate ion (CO₃^2-), the following steps can be performed:

• Take a small amount of the compound or solution suspected to contain the carbonate ion.
• Add a few drops of dilute acid, such as hydrochloric acid (HCl), to the sample.
• If the carbonate ion is present, effervescence (bubbling) will occur due to the evolution of carbon(IV) oxide gas.
• To confirm the presence of carbon(IV) oxide, pass the evolved gas through limewater (a solution of calcium hydroxide, Ca(OH)₂).
• If carbon(IV) oxide is present, the limewater will turn milky due to the formation of a white precipitate of calcium carbonate (CaCO₃):
  Ca(OH)₂(aq) + CO₂(g) → CaCO₃(s) + H₂O(l)

Note: It is important to remember safety precautions while performing experiments or working with chemicals. Handle chemicals responsibly and follow appropriate laboratory procedures to ensure safety.