Why is it important that the thermometer does not touch the sides or bottom of the test tube when measuring temperature during an experiment involving thermal equilibrium?

• A. To avoid contaminating the solution with glass particles.
• B. To allow the thermometer to cool down faster after use.
• C. To ensure the thermometer measures the temperature of the solution, not the glass, which may be at a different temperature.
• D. To prevent the thermometer from breaking due to contact with the glass.

Answer: (C)

Verified step by step guidance

1. Understand that when measuring temperature in a solution, the goal is to obtain the temperature of the liquid itself, not the container holding it.
2. Recognize that the glass of the test tube can have a different temperature than the solution, especially if the test tube was recently heated or cooled.
3. If the thermometer touches the sides or bottom of the test tube, it may register the temperature of the glass instead of the solution, leading to inaccurate readings.
4. By suspending the thermometer in the solution without touching the glass, the thermometer bulb is in direct contact with the liquid, allowing it to reach thermal equilibrium with the solution.
5. This ensures that the temperature reading reflects the true temperature of the solution, which is critical for accurate experimental results.