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

What does the reaction between an acid and an alkali generate?

1. Salt and carbon dioxide

2. Only salt

3. Salt and water

4. Acid and water

The correct answer is: Salt and water

The reaction between an acid and an alkali is known as neutralization. This process typically produces a salt and water as products. In this reaction, the acid donates protons (H⁺ ions), while the alkali provides hydroxide ions (OH⁻). When these ions combine, they form water (H₂O) through the reaction: H⁺ + OH⁻ → H₂O Simultaneously, the remaining ions from the acid (anions) and alkali (cations) combine to form a salt. For example, if hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH), the resulting products are sodium chloride (NaCl), which is the salt, and water. This fundamental reaction is vital in many chemical processes, including titrations and the preparation of salts in laboratories, emphasizing the importance of understanding neutralization as a foundational concept in chemistry.