Below 4 degrees Celsius, does the density of water become higher or smaller?

Smaller, at four degrees Celsius the density of water is the largest, can explain to you why the density is highest at this time, it doesn't matter if you don't understand it.

It has to do with hydrogen bonding.

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 (H2O)3 association molecules, when the temperature rises to the water molecules, the water molecules mostly exist in the form of (H2O)2 association molecules, the molecules occupy a relatively small space, and the density of water is the largest at this time. If the temperature continues to rise above this, the law of thermal expansion and cold contraction of general matter will prevail. 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 water molecules in the ice is that each oxygen atom has four hydrogen atoms as close neighbors (two covalent bonds, two hydrogen bonds), as shown in the figure.

This arrangement results in an open structure, which means that there are large voids in the structure of the ice, so that the density of the ice is inversely smaller than that of water at the same temperature.

In addition, it takes a certain amount of energy to disassemble the associated molecules, which is enough to explain why water has a large specific heat.

The "associative molecules" referred to here are formed by hydrogen bonding.

The main reason for the formation of hydrogen bonds is that the anion has a strong ability to seize electrons, so that the hydrogen atoms of non-homogeneous molecules are also close to it, it is a much stronger force than the intermolecular force, so that many molecules can be concentrated together to form a super-large molecular group, which can increase the melting and boiling point of the substance.

Water is very special: 4 degrees Celsius, the density is the highest, the temperature goes up and down, and the density becomes smaller.

The next poop is smaller. It's smaller than it is up.

Water density is greatest at 4 degrees Celsius.

The density of water is determined by two factors: the association of water molecules and the thermal motion of water molecules. When the temperature increases, the thermal movement of water molecules accelerates and the association effect is weakened. When the temperature decreases, the thermal motion of water molecules slows down and the association intensifies. Considering the influence of these two factors, we can know the law of water density change.

The nature of abnormal expansion of water: the density of water is the highest at 4, and when it is above 4, water is thermally expanded and contracted, but there is an anomaly of cold expansion and thermal contraction below, and the ice of 0 is about 11% larger than the volume of water at 4The abnormal expansion of the water when it freezes can cause the tank to freeze and crack.

Your question itself is wrong, the density of water at 4 is the maximum.

It is a fact that the density of water is at its highest at 4:

Tests in glacial lakes have shown that in frozen lakes, the density of the water below the ice surface increases from top to bottom (of course, the heavier is lower and the lighter is higher), and the temperature increases from top to bottom, from 0 in the surface water to 4 in the bottom waterBecause of this property, the fish in the lake are able to hide in the bottom water in the harsh winter without being frozen into ice.

— Why is this happening? ——

The maximum density of water at 4 is determined by the special structure of hydrogen bond association between water molecules. According to recent X-ray studies, it has been proved that ice has a tetrahedral crystal structure. This tetrahedron is formed by hydrogen bonding, which is an open relaxation structure, because five water molecules cannot take up the volume of all tetrahedra, and hydrogen bonds in ice connect these tetrahedra into a whole.

This directional and orderly arrangement formed by hydrogen bonding has a small space utilization rate, accounting for about 34, so the density of ice is small.

A large number of hydrogen bonds are dismantled when the water solution is dissolved, so that the whole is divided into tetrahedral groups and sporadic smaller "water molecule groups" (i.e., some association molecules formed by the association of hydrogen bonds), so liquid water is no longer completely arranged in order like ice, but has a certain degree of disordered arrangement, that is, the distance between water molecules is not fixed as in ice, and H2O molecules can enter another microcrystalline from one tetrahedral crystallite. In this way, the voids between the molecules are reduced, and the density increases.

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 molecules also increases the distance between molecules, which reduces the density. 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.

If it is 4 degrees Celsius, the state traces are under the piece:

The density of water is: 1kg l

1000ml=1l

1kg l *1l=1kg=2 catties.

The density of p at any point in an object is defined as:

where <>

v is the volume element containing the p-point; <>

m is the mass of the volume element. In the centimeter-gram-second system, the unit of density is gram centimeter3; In the International System of Units and the Chinese Legal Unit of Measurement, the unit of density is kilogram m3.

The density of water at four degrees Celsius is 1 kilogram per cubic decimeter, which is also 1 10 kilograms per cubic meter.

Water is densest at four degrees Celsius and becomes less dense when the temperature is above or below four degrees Celsius. However, this change is very small, and it is ignored in physical calculations, and 1,000 cubic decimeters or 1 10 kilograms of cubic meters of scum are often used as the density of water.

The density of water will change with the change of temperature, usually take 1 10 3kg m 3.

Density of water: The density of water is maximum when it is 1 10 3kg m3, when water is 0, the density is , and when ice is 0, the density is.

Water is a colorless and odorless transparent liquid at constant temperature and pressure, and is known as the source of human life. Water, including natural water (rivers, lakes, atmospheric water, seawater, groundwater, etc.).

About the physical and chemical properties of water:

Water is a colorless, tasteless, and odorless liquid at room temperature.

The density of water is the highest (1000 kg m 3 is often taken in approximate calculations). The density of solid water (ice) is smaller than that of liquid water, so ice can float on the water. When the water freezes, the volume increases slightly. Slow noise shed.

At standard atmospheric pressure, pure water has a boiling point of 100 and a freezing point of 0.

Many common gases can be dissolved in water, such as hydrogen, oxygen, nitrogen, carbon dioxide, inert gases, etc., and the solubility of these gases is related to factors such as temperature, pressure disturbance, and partial pressure of the gas phase.