Understanding the Neutralisation Reaction

The question asks for the specific chemical process where acids react with bases to form salts and water. This reaction is fundamental in chemistry and has a widely accepted name.

What Happens in this Reaction?

Acids are substances that typically donate protons (H⁺ ions), and bases are substances that typically accept protons or donate hydroxide ions (OH⁻). When an acid and a base react, the H⁺ ions from the acid combine with the OH⁻ ions from the base to form water (H₂O). The remaining parts of the acid (the anion) and the base (the cation) combine to form a salt.

A general representation of this reaction is:

\(\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}\)

For example, the reaction between hydrochloric acid (\(\text{HCl}\)) and sodium hydroxide (\(\text{NaOH}\)) is a neutralisation reaction:

\(\text{HCl(aq)} + \text{NaOH(aq)} \rightarrow \text{NaCl(aq)} + \text{H}_2\text{O(l)}\)

Here, hydrochloric acid is the acid, sodium hydroxide is the base, sodium chloride (\(\text{NaCl}\)) is the salt, and water is formed.

Analyzing the Options

Let's look at the given options to determine which one correctly describes this process:

• Hydrolysis: This is a reaction in which a molecule of water is broken down into hydrogen cations (\(\text{H}^{+}\)) and hydroxide anions (\(\text{OH}^{-}\)) and these ions react with another compound. It's essentially the reaction of a substance with water, often breaking it down. This is different from an acid-base reaction forming salt and water.
• Electrolysis: This is a process that uses an electric current to drive a non-spontaneous chemical reaction. It involves breaking down substances into their constituent elements or simpler compounds using electricity. This is not an acid-base reaction.
• Neutralisation: As discussed above, this is precisely the reaction between an acid and a base, resulting in the formation of salt and water. The acid and base properties are essentially 'neutralised' to form neutral substances like water and often neutral salts (though some salts can be acidic or basic).
• Distillation: This is a separation technique used to separate liquids with different boiling points or to separate a liquid from a solid. It involves heating a liquid to its boiling point, converting it into vapor, and then cooling the vapor back into a liquid. This is a physical separation method, not a chemical reaction between acids and bases.

Based on the analysis, the process in which acids and bases react to form salts and water is called neutralisation.

Revision Table: Comparing Chemical Processes

Additional Information on Neutralisation Reactions

Neutralisation reactions are very common and important in various applications:

• Titration: Used in analytical chemistry to determine the concentration of an unknown acid or base.
• Antacids: Medications that contain bases (like magnesium hydroxide or calcium carbonate) to neutralise excess stomach acid (hydrochloric acid) and relieve heartburn.
• Wastewater Treatment: Used to adjust the pH of industrial wastewater before it is discharged into the environment. Acidic or alkaline waste streams are neutralised.
• Soil Treatment: Lime (calcium oxide or calcium hydroxide, which are bases) is added to acidic soils to neutralise them and make them more suitable for agriculture.

The pH of the resulting solution after neutralisation depends on the strength of the acid and base reacted. A strong acid and a strong base yield a neutral solution (pH ≈ 7), while reactions involving weak acids or weak bases can result in slightly acidic or basic solutions.