Observed phenomena:

1. Before boiling, the thermometer’s reading continued to increase and finally remained unchanged.

2. When boiling, bubbles appear inside and on the surface of the water at the same time, and the bubbles become larger as they rise.

3. The sound of water is loud before boiling and becomes smaller after boiling.

4. Before boiling, bubbles only appear at the bottom, and become smaller and smaller as they rise.

Analysis

1. Because the water temperature rises first, it continues to absorb heat after reaching the boiling point, but the temperature remains unchanged;

2. Due to the process of bubbles rising , the depth decreases. According to p=pgh, it can be seen that the pressure on the bubble gradually decreases, so the bubble becomes larger as it rises.

This question is an experimental question about "observing the boiling of water". When solving the problem, you should understand the characteristics of boiling.

It can be analyzed from the sound size and temperature changes before and after boiling; after the water reaches the boiling point, it continues to absorb heat, but the temperature remains unchanged.

Extended information:

The difference between evaporation and boiling

(1) Evaporation is a vaporization phenomenon that can occur in liquids at any temperature (ignoring -273.15℃ , because -273.15℃ is absolute zero, at which point the molecules stop moving), and boiling is a vaporization phenomenon that can only occur when a liquid continues to be heated at a certain temperature (boiling point).

(2) Evaporation is a slow vaporization phenomenon that only occurs on the surface of a liquid, while boiling is a violent vaporization phenomenon that occurs on the surface and inside of a liquid simultaneously.

(3) The temperature of the liquid will decrease during evaporation, but the temperature of the liquid will remain unchanged during boiling (provided that the pressure on the liquid surface does not change).

(4) The factors that affect the evaporation rate are: the surface area of ??the liquid, the temperature of the liquid, and the air flow rate near the liquid surface; the factors that affect the boiling point are: the air pressure on the liquid surface, and the purity of the liquid. Factors that affect boiling speed: liquid volume and original temperature