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

What process is described by mixing an acid with a base to bring the pH to neutral?

1. Evaporation

2. Neutralization

3. Filtration

4. Crystallization

The correct answer is: Neutralization

Mixing an acid with a base to bring the pH to neutral is referred to as neutralization. In this process, the acidic properties of the acid and the basic properties of the base react with each other, resulting in the production of water and a salt. A neutral pH of 7 is achieved, signifying that the resulting solution does not exhibit the properties of either an acid or a base. Neutralization is a fundamental chemical reaction and is essential in various applications, such as treating acidic or alkaline waste, adjusting soil pH in agriculture, and in many laboratory settings where specific pH levels are required. Each pairing of acid and base will produce a different salt, and the overall reaction can be summarized with the general equation: Acid + Base → Salt + Water. In contrast, the other processes mentioned do not involve this reaction. Evaporation pertains to the transition of a liquid to a gas, filtration is used to separate solids from liquids or gases, and crystallization is a method to purify compounds by forming solid crystals from a solution. Thus, the process being described aligns precisely with neutralization.