Physics Why oil solidifies from top to bottom, while water goes from bottom to top

You said that the ...... was reversed

Water solidifies from top to bottom, and oil solidifies from bottom to top.

This is due to the anti-expansion of water, when the water is near the freezing point, it is heat shrinking and cold rising, so the density of ice is less than that of water, and the density of solidified water is less than that of water that is not solidified, so it floats on it.

The normal oil is thermally expanded and contracted, and the density of solidified oil is greater than that of non-solidified oil, so the solidified oil sinks to the bottom.

So it looks like there's going to be a top-down and bottom-up ......The team will answer for you.

That's wrong. It should be that the oil solidifies from the bottom to the top, and the water from the top to the bottom.

This is because water has the property of abnormal expansion, and the density of ice is less than that of water, so ice will float on the surface of the water.

The density of the oil solid state is greater than that of the liquid oil, so the oil solidifies from the bottom to the top.

Teenager: Does the river freeze first at the top or below? The direction of solidification mainly depends on the direction of heat transfer. The oil or water side loses heat and the other side solidifies first.

Heh, I'm going to explain the different directions downstairs.

Solid water, also known as ice, is less dense than water, and it floats as soon as it freezes. And the opposite is true of oil.

The physical properties of water are that the volume is minimal at 4 degrees Celsius, and the specific gravity of water is smaller than that of water when it freezes at 0 degrees, and the ice is on the surface of the water. This is a special case.

Where the heat dissipates quickly, freeze or solidify first, and you put the water in a container with good heat transfer and put it in the freezer compartment of the refrigerator to ensure that the bottom freezes first.

Why does oil solidify from the bottom and water from above? Usually the temperature of water is 4 degrees Celsius at its peak, ice is less dense than water, and objects with less density float on top of objects with higher density, so water always begins to solidify from above, while the bottom temperature always remains around 4 degrees Celsius. Oil is physically classified as amorphous, with no fixed solidification temperature, and the lower the temperature, the higher the density, the denser it sinks underneath the less dense, so the oil always begins to solidify from below.

It is necessary to explain in detail that liquid solidification (crystallization) requires condensation nuclei, so both dust and container walls on the surface of the water can be regarded as condensation nuclei, so it can be seen that water begins to solidify from the liquid surface close to the container wall. Moreover, there is surface tension on the surface of the liquid, which seems to have an inherent effect on condensation. Because 4C° water is denser and larger than 0C° water, 0C° water will float to the surface and solidify first.

Therefore, in winter, the surface water is close to 0 degrees, and the deeper the depth, the higher the temperature, gradually approaching 4 degrees Celsius.

Liquids undergo a physical change from liquid to solid at a certain temperature, and edible vegetable oil is no exception. At a certain low temperature, the liquid state of edible vegetable oil gradually changes from clear and transparent to hazy, and the precipitate gradually appears in a solid-liquid mixed state, and finally completely turns into a solid state, which is commonly called freezing (similar to the phenomenon of water freezing). The freezing point of the oil is also not a definite temperature, but a range.

It will start to show a little flocculent at a certain temperature, but it may not all solidify.

The solidification of peanut oil is also a gradual process, when the temperature drops to near the critical point of 10, the peanut oil will produce some flocculents, and the oil will become turbid. The freezing point of soybean oil is below -10 degrees Celsius, and the freezing point of oil is also not a definite temperature, but a range. It will start to show a little flocculent at a certain temperature, but it may not all solidify.

The solidification of peanut oil is also a gradual process, when the temperature drops to near the critical point of 10, the peanut oil will produce some flocculents, and the oil will become turbid. The physical change of edible vegetable oil solidification in winter does not affect the quality of the product, the solid substance in edible oil is saturated fat, which does not need to be removed, and the vegetable oil is still triglyceride after solidification, without any chemical change, and it will still become clear and transparent after the temperature rises. As long as the product meets the national standard, it can be eaten normally.

Because the density of the oil is relatively large, and the bottom is larger.

And the lower the temperature, the greater the density, and the denser it sinks below the less dense, so the oil always begins to solidify from below.

There is no fixed solidification temperature, and the lower the temperature, the higher the density.

The density of oil is relatively large, and the density of moisture is not as large as that of oil.

Because the density of these two is different.

Because the density of oil is relatively large

, the less dense object floats on the denser object, so the water always starts to solidify from above, and the bottom temperature is always kept around 4 degrees Celsius.

This is because of the density of the problem.

Because of some physical reactions.

Analysis] When water and oil are placed in a low temperature environment, the temperature of the water and oil in the surface layer will gradually decrease due to heat exchange. Oil, like most substances, when the temperature decreases, the volume decreases, and the density increases, so the oil on the surface sinks, and the oil below floats, and after a certain period of time, the temperature of the oil in the cup reaches the freezing point. As the ambient temperature is lower, the oil continues to exothermic to reduce the temperature, the volume continues to shrink, the density increases, and the oil at low temperature on the surface layer sinks and begins to solidify, so the oil begins to solidify from the bottom.

Water has abnormal expansion characteristics, above 4, the temperature decreases, the volume decreases, the density of orange absolute increases, the same thing after a certain period of time of up and down convection, the water temperature in the cup reaches 4, later, when the temperature decreases, the water appears abnormal expansion, that is, the volume increases, the density of the spike orange decreases, therefore, in the cooling process below the circle group 4, the water of the surface layer is cooled first, until 0, and begins to freeze, and the water temperature of the lower layer is still higher than 0, so the water in the cup begins to solidify from the top. Therefore, the answer should be C. 【Comments】 To solve this problem, we should pay attention to the characteristics of water, generally substances are thermal expansion and cold contraction, and water is different, water is cold expansion and heat contraction below 4.

So the ice starts to form from the surface of the water.