International General Certificate of Secondary Education (IGCSE) Chemistry Practice Exam

What is the product of the general reaction between an acid and a base?

1. Salt and carbon dioxide

2. Salt and hydrogen

3. Salt and water

4. Salt and oxygen

The correct answer is: Salt and water

In the general reaction between an acid and a base, the primary products formed are salt and water. This reaction is known as a neutralization reaction. When an acid donates protons (H⁺ ions) to a base, which accepts them (usually hydroxide ions, OH⁻), they combine to form water (H₂O). Meanwhile, the remaining ions from the acid and the base combine to form a salt. For example, if hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), the products will be sodium chloride (NaCl), which is the salt, and water. This foundational concept illustrates the balancing of acid-base reactions, emphasizing the formation of neutral compounds that result from interactions of acidic and basic substances. Alternative products mentioned, such as carbon dioxide, hydrogen, or oxygen, do not universally characterize acid-base reactions. These products may appear in specific reactions, but they are not the general outcome of an acid reacting with a base.