Why the density of cold water is different from that of hot water

Because every object has internal energy, which is caused by the thermal movement of molecules, when you heat and chase, the temperature rises, the thermal motion accelerates, the internal energy increases, the molecular diffusion is fast, the distance between molecules becomes larger, and the density is larger, while the thermal movement of molecules in cold water is slow, the diffusion is slow, the distance is small, and the density is small. The density of water is the lowest at 4, which is the critical point of water density, and when it is lower, it becomes larger when it freezes.

Agree that the internal energy is the energy possessed by the object itself, which is the manifestation of the energy possessed by the molecule itself. After heating, the molecules gain energy, the irregular movement accelerates, the distance between molecules increases, the volume increases, the mass remains unchanged, and the density decreases. However, there are hydrogen bonds in water, and when the temperature is low enough and the molecular energy is not enough to offset the effect of hydrogen bonds, hydrogen bonds will have a tendency to maintain the distance between molecules, so hydrogen bonds below 4 degrees Celsius will be the volume of water will become larger and the density will be smaller.

In particular, hydrogen bonding is not a chemical bond, and there are also hydrogen bonds in ice, but the impact reaches an extreme and cannot produce greater energy to reject the approaching or distant movement of molecules, so ice still conforms to the principle of thermal expansion and cold contraction.

10 The density of cold water is; 90 The density of hot water is.

at an atmospheric pressure.

The temperature range of the water is 0 degrees Celsius.

between 100 degrees Celsius.

Between 4 degrees Celsius and 100 degrees Celsius, the density of cold water is greater than that of hot water. Mainly because the higher the temperature, the greater the distance between the molecules, i.e., the less density.

Between 0 degrees Celsius and 4 degrees Celsius, cold water is less dense than hot water, and the lower the temperature, the less dense it becomes. The reason is that between 0 and 4 degrees Celsius, the microstructure of water gradually approaches that of ice, so that the density becomes smaller. At 4 degrees Celsius, water is at its densest.

The law of change in density.

Generally speaking, no matter what substance it is in, no matter what state it is in, with the change of temperature and pressure, the volume or density will also change accordingly. The three physical quantities of temperature t, pressure f, and density (or volume) are linked.

The relationship is called the equation of state. The volume of a gas varies significantly depending on the pressure it is subjected to and the temperature it is subjected to.

If its temperature does not change, the density is proportional to the pressure; If its pressure is constant, the density is inversely proportional to the temperature. For general gases, if the density is not large and the temperature is far away from the liquefaction point, its volume changes with the pressure of acacia close to the ideal gas.

For gases with high density, the above equation of state should also be appropriately modified.

The density of water does not vary linearly with temperature, and it is not possible to say in general terms whether hot water is dense or cold water is denser. Water is at its densest.

The density of water is the largest at 1000kg m3, when the temperature is higher than (it can also be ignored as 4), the density of water decreases with the increase of temperature, and at 0, the water shrinks and cools up, and the density increases with the increase of temperature.

Reason: Mainly determined by the arrangement of molecules. It can also be said to be caused by hydrogen bonding. Due to water molecules.

It has strong polarity and can be combined into associative molecules by hydrogen bonding.

Liquid water, in addition to simple water molecules (HO), also contains association molecules (HO)2 and (HO)3, etc., when the temperature is 0 When the water is not frozen, most of the water molecules exist as association molecules of (HO)3.

When the temperature rises, the water molecules mostly exist in the form of (HO)2 association molecules, and the space occupied by the molecules is relatively reduced, and the density of water is the largest at this time.

If the temperature continues to rise above this, the general substance expands and contracts coldly.

The law is dominant.

When the water temperature drops to 0, the water freezes, and when the water freezes, almost all the molecules are associated together to become a huge association molecule, and the arrangement of the water molecules in the ice is each oxygen atom.

There are four hydrogen atoms.

This arrangement of the two hydrogen bonds in the immediate vicinity results in an open structure in which there are large voids in the structure of the ice, so the density of the ice is inversely proportional.

The water of the same temperature is small.

Supercritical water properties

When we raise the temperature and pressure of the water to a critical point.

temperature, pressure, water will be in a fluid state that is different from both gaseous and liquid and solid states - supercritical state.

The water in this state is called supercritical water (SCW).

Supercritical water is compressible, and a small change in temperature or pressure will cause the density of supercritical water to decrease greatly, and at the critical point, the density of water is only, and typical supercritical water oxidation is carried out when the density is approaching.

The above content reference: Encyclopedia - Water.

There is no comparison, and 4 degrees of water is the most dense.

The lower the temperature of 4 degrees, the smaller the density, and above 4 degrees, the higher the temperature, the smaller the density, and the lower the temperature below 0 degrees, the greater the density, so the cold water above four degrees is denser than hot water, and the density of cold water below four degrees is not necessarily greater than that of hot water.

When the temperature increases, the tetrahedral group of water molecules is continuously destroyed, and the disordered arrangement of the molecules increases, so that the density increases. But at the same time, the thermal motion between the molecules also increases the distance between the molecules, so that the density decreases. These two contradictory factors reach equilibrium at 4 o'clock, therefore, the density of water is highest at 4 o'clock.

After 4, the thermal motion of the molecules increases the distance between the molecules, and the density of the water begins to decrease again.

Because the low-density solution always floats on top of the denser solution, the blue hot water floats on the surface of the cold water because it is less dense than the cold water, but when the hot water gradually cools, it will mix with the cold water.

The density of water does not change linearly with temperature, and it is not possible to say in general terms whether hot water is dense or cold water is denser.

The density of water is high.

The density of water at 4 is 1g cm3, at which time the volume of water is the smallest, and the density of ice is about 90% of the density of pure water, ie. Therefore, the density of water is greater than that of ice.

At room temperature, the density of ice is and the density of water is, so the density of ice and water is greater than the density of water. Density is a property of matter, which does not change with the change of mass and volume, but only with the change of temperature and pressure of the state of matter.

Density is a measure of the mass within a specific volume, density is equal to the mass of an object divided by the volume, which can be expressed by symbols, in the International System of Units and the Chinese legal unit of measurement, the unit of density is kilogram meters.

When liquid water solidifies into ice, the interaction force between molecules makes the molecules arrange according to a certain rule, and each molecule is surrounded by four molecules, forming a crystalline tetrahedron This arrangement is relatively loose, so that the average distance between molecules in the ice crystal is greater than the average distance between molecules in liquid water.

It's not the same. The density of water is high. Because the density of ice at 0 is and the density of water is normal, in daily life, ice is always floating on the water, which can also indicate that the buoyancy of ice is small and the buoyancy of water is large.

Water freezes, and when water freezes, almost all the molecules are associated together to become a huge association molecule, and the arrangement of water molecules in ice is that each oxygen atom has four hydrogen atoms as neighbors (two covalent bonds, two hydrogen bonds), and this arrangement leads to an open structure, that is, there are large voids in the structure of the ice, so the density of ice is smaller than that of water at the same temperature.

The density of water at different temperaturesThe density of water at 0 degrees Celsius is kilograms per cubic meter; The density of water at 1 degree Celsius is kilograms per cubic meter; The density of water at 2 degrees Celsius is kilograms per cubic meter; The density of water at 3 degrees Celsius is kilograms per cubic meter; The density of water at 4 degrees Celsius is kilograms per cubic meter; The density of water at 5 degrees Celsius is kilograms per cubic meter.

The density of water at 4 is 1g cm3, when the volume of water is the smallest and the density is maximum.

The density of ice is about 90% of the density of pure water, ie. Therefore, the density of water is greater than that of ice.

Liquid water, in addition to containing simple water molecules (H2O), also contains association molecules (H2O)2 and (H2O)3, etc., when the temperature is 0 When the water is not frozen, most of the water molecules exist as association molecules of (H2O)3, when the temperature rises to .

kPa), the water molecules mostly exist in the form of (H2O)2 associated molecules, and the space occupied by the molecules is relatively reduced, and the density of water is the largest at this time. If the temperature continues to rise again.

Above, the law of thermal expansion and cold contraction of general matter is dominant. The water temperature drops to 0

When the water freezes, almost all the molecules are associated together to become a huge association molecule, and the arrangement of water molecules in the ice is that each oxygen atom has four hydrogen atoms as neighbors (two covalent bonds, two hydrogen bonds), so this arrangement leads to an open structure, that is to say, there are large voids in the structure of the ice, so the density of the ice is smaller than that of water at the same temperature.

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