Test tubes are one of the most iconic and fundamental elements in any chemistry laboratory. These simple yet versatile instruments are used in a wide variety of experiments and tests. Below, their use, types, handling, and care in the laboratory are detailed.

1. Description and General Use

• Description: Test tubes are transparent glass cylinders, open at one end and rounded at the other.
• Common Uses: They are used to contain, mix, heat, and react small quantities of liquids or solids.

2. Types of Test Tubes

• Ordinary Glass Tubes: Suitable for most thermally non-demanding experiments.
• Borosilicate Glass Tubes: Resistant to sudden temperature changes and aggressive chemicals. Ideal for heating and experiments requiring greater thermal resistance.
• Plastic Tubes: Used in applications where heating is not required and there is a risk of breakage.

3. Handling and Use Techniques

• Heating: Use a Bunsen burner flame, distributing the heat evenly to prevent the glass from breaking.
• Mixing Substances: Gently shake or use stirring rods to mix the contents.
• Use of Tongs: Use special test tube tongs when heating to avoid burns.

4. Cleaning and Storage

• Cleaning: Clean immediately after use to prevent residues from sticking. Use special test tube brushes and appropriate detergents.
• Storage: Store in racks or shelves for test tubes. Ensure they are dry before storing to prevent mold growth.

5. Safety Precautions

• Avoid Overheating: Do not expose to intense flames that can cause the glass to break.
• Pre-Use Inspection: Check for cracks or damage before use, especially if they are going to be heated.
• Handling Broken Glass: Follow safety protocols in case of breakage, such as using appropriate tools to pick up the fragments and disposing of them in specific containers for broken glass.

6. Specific Applications in Experiments

• Small Scale Chemical Reactions: Ideal for observing color changes, formation of precipitates, and gas release.
• Heat and Solubility Tests: Melting point, boiling point, and solubility tests of substances can be performed.

When using test tubes in the laboratory, it is important to understand their proper use and limitations to ensure safe and effective experiments. These tubes, although simple, are essential tools in the world of chemistry and scientific research.