Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What method is preferred for diluting strong acids?

1. Mix strong acid with an equal amount of water

2. Add strong acid to water gradually

3. Always start with water

4. Combine strong acid and base simultaneously

The correct answer is: Add strong acid to water gradually

The preferred method for diluting strong acids is to add the strong acid to water gradually. This technique is essential for safety reasons. When acid is mixed with water, it can release a significant amount of heat due to the exothermic reaction. If water is added to a strong acid, it can cause the solution to heat up rapidly, potentially leading to splattering or violent reactions, as the concentrated acid can cause the water to vaporize instantly. By adding the acid to water, the initial volume of water can absorb some of the heat, and the resulting mixture becomes less concentrated, reducing the risk of splattering and allowing for a safer dilution process. This approach also ensures that the acid is evenly mixed throughout the water as it is added, which helps control the heat generated during the dilution. Other methods, like mixing equal amounts or starting with water, do not prioritize safety and control in the same effective manner, while combining acid and base at the same time introduces additional risks due to the potential for rapid neutralization and heat production.