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

What is needed to heat liquids safely in a laboratory without risk of fire?

1. Water bath

2. Direct flame

3. Hot plate

4. Heating mantle

The correct answer is: Water bath

Using a water bath is a safe method for heating liquids in a laboratory setting because it eliminates the risk of direct exposure to flames or excessively high temperatures that could lead to volatile reactions or even fires. The water bath provides controlled and even heating, allowing for gentle warming of the liquid without overheating. This is particularly important when working with substances that are flammable or sensitive to temperature changes. The other methods may involve higher risks. A direct flame can ignite vapors or create an uncontrolled heating situation, leading to potential fires. A hot plate, while commonly used in laboratories, can pose risks if not monitored carefully, particularly with flammable substances. A heating mantle, although effective for heating, typically requires careful handling as it can also pose fire hazards with volatile liquids. Therefore, a water bath is the most suitable and safest choice for heating liquids.