When carbon dioxide is bubbled through a clear calcium hydroxide solution, the solution appears milky. Write an equation for the reaction and explain how this reaction illustrates that \(\mathrm{CO}_{2}\) is an acidic oxide.

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Through chemical bonds breaking and new ones forming, reactants become products, displaying new properties and compositions.

For instance, when carbon dioxide comes into contact with calcium hydroxide, a chemical reaction occurs. This reaction is characterized by the formation of calcium carbonate and water, showcasing a change in the physical appearance of the solution, from clear to milky. This transformation from reactants to products is essential to understanding chemical processes and their underlying principles.

Calcium hydroxide, often referred to as lime water, is a chemical compound with the formula \( \mathrm{Ca(OH)}_2 \). It is a colorless crystal or white powder and is obtained from calcium oxide by adding water, a process called slaking. It is an alkaline solution and is used for various purposes, including as a neutralizing agent in agriculture and in the preparation of ammonia gas.

When used in chemical reactions, calcium hydroxide can neutralize acids to form corresponding salts and water, making it an essential player in many acid-base interactions. For example, when calcium hydroxide interacts with carbon dioxide, an acidic oxide, it produces calcium carbonate and water.

Calcium carbonate precipitation occurs when calcium ions \( \mathrm{Ca}^{2+} \) combine with carbonate ions \( \mathrm{CO}_3^{2-} \) to form \( \mathrm{CaCO}_3 \), an insoluble compound. This process is visually identifiable as the substance forms a solid precipitate, which is observable as cloudiness or milkiness in a solution, and is commonly referred to as 'lime scale' when found in kettles and hot water pipes.

Such precipitation is a crucial process in geology, forming limestone and other rock types, and is also integral to the hardness of water. In the context of the reaction between calcium hydroxide and carbon dioxide, the production of calcium carbonate is a tell-tale sign of the reaction’s progression.

Carbon dioxide \( \mathrm{CO}_2 \) is a colorless gas with a slightly acidic taste and a faint sharp odor. It is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom.

As an acidic oxide, carbon dioxide reacts with water to form carbonic acid \( \mathrm{H}_2\mathrm{CO}_3 \), making the environment more acidic. When in contact with strong bases like calcium hydroxide, it undergoes a chemical reaction that results in the formation of a salt and water - indicative of its acidic behavior. This characteristic contributes to a wide array of biological and chemical phenomena, including respiratory functions in living organisms and the carbonation in beverages.