In winter, if you boil water with gas, you will often find many drops of water at the bottom of the kettle. Is the kettle leaking? However, when you are still wondering, you find that the water drops at the bottom of the pot have magically disappeared. But the next time I boil water, this strange phenomenon happens again. Check the kettle carefully, but you can't find the damage. Why on earth is this?
It turns out that coal gas will react chemically during combustion to produce water. If it is in summer and the temperature is high, the water will diffuse in the air in gaseous form. However, the temperature in winter is low. At the beginning of boiling water, the temperature of the water in the kettle is still low and the bottom of the kettle is cooler. Therefore, the water vapor generated by combustion will condense at the bottom of the kettle when it is cold, resulting in the illusion of water leakage of the kettle. With the continuous heating, the temperature of the water in the pot rises gradually, the bottom of the pot is no longer cold, and the water droplets condensed on it will turn into gas again and disappear.
There are many similar phenomena in daily life. For example, on a winter morning, we often find a layer of water mist on the inside of the glass window; On a summer morning, water mist appears on the outside of the glass window. This is because it is warm inside and cool outside in winter, and the water vapor in the air in the window condenses inside the glass window when it is cold; In summer, it is cool inside and hot outside. The water vapor in the air outside the window condenses on the side of the glass window when it is cold. Both phenomena are related to the vapor pressure of water. The vapor pressure of water increases with the increase of temperature, and the vapor pressure of water reaches 1.01 × 105 PA (1 ATM), so the temperature of domestic water when boiling is 100 ℃. When the temperature inside the house is higher than outside, the water vapor pressure inside the house is higher than outside, and the water vapor will condense inside the glass window; On the contrary, it condenses on the side of the glass window.