Carbonates

Carbonates: Basic Definitions

• A carbonate is a type of salt that contains the carbonate ion, written as CO3 2-.
• Carbonates are usually produced in reactions involving acid-base neutralisation.
• The pH of a carbonate solution is typically higher than 7, which means they’re alkaline.

Properties of Carbonates

• In water, they often partially dissolve, producing hydrogencarbonate ions (HCO3-) and hydroxide ions (OH-) which makes the solution alkaline.
• When heated, most carbonates tend to decompose. For example, heating copper carbonate breaks it down into copper oxide and carbon dioxide gas.
• Carbonates react with acids to produce carbon dioxide, a salt and water. This reaction is often used in the identification of carbonates.

Common Examples of Carbonates

• Calcium carbonate (CaCO3), commonly known as limestone or chalk, is one of the most well-known examples.
• Sodium carbonate (Na2CO3) and potassium carbonate (K2CO3) are also common examples.
• Other metal carbonates include those of copper (CuCO3), zinc (ZnCO3), and iron (FeCO3).

Reactions Involving Carbonates

• Carbonates react with acids to produce carbon dioxide, a salt, and water. This reaction is often used in qualitative analysis of carbonates.
• Carbonates also react with oxides and hydroxides to create more complex compounds.
• Decomposition by heating a carbonate, like calcium carbonate, leads to the formation of an oxide (like calcium oxide) and the release of carbon dioxide.

Uses of Carbonates

• Carbonates are commonly used in the production of glass, ceramics, and cement.
• Sodium and potassium carbonates are frequently used as cleaning agents.
• Calcium carbonate, in its crushed form, is used as a neutralising agent for soil acidity.
• Carbonates are also used in the soda lime used by anaesthetists to absorb carbon dioxide in a patient’s exhaled air during surgery.