Why lowering the temperature can reduce the pressure. On the contrary, it increases?

Gas pressure: The pressure of gas molecules on the wall of the device per unit area. The more intense the molecular movement, the greater the pressure on the wall of the organ, and the greater the pressure; Conversely, the pressure decreases.

When the temperature is lowered, the molecular movement decreases, so the pressure decreases.

The gas pressure formula used in general high school: n=pv t(n: constant. p: Gas pressure. v: volume. t: temperature).

Learning Experience: To learn physical chemistry, first understand the definition, then the formula. It's important, but it's easy to overlook, and it can't just be a general understanding!! ）

1) For the first floor, the formula is PV=Nrt, where P is the pressure, V is the volume, N is the amount of matter, R is the molar gas constant, and T is the temperature (in Kelvin).

2) The pressure is actually the pressure of the molecule on the container, and this pressure is actually caused by the molecule colliding with the container, and the increase in temperature leads to an increase in internal energy, which leads to the acceleration of the molecular movement rate, resulting in a more violent collision of gas against the container, resulting in an increase in pressure.

It can be noted that water, when the temperature rises, water vapor is produced, and the pressure increases under the same volume. On the contrary, it will naturally decrease! That's how I remember it anyway, and if you can't understand the explanation, you can remember it like this.

According to the formula: PV=RT, where r is a constant.

So. Reducing the temperature can reduce the pressure; On the contrary, it increases?

1.Air pressure is the pressure of the atmosphere on the ground, so in general, the higher the altitude, the shorter and less dense the air column, so the lower the pressure--- the same place, the air pressure on the ground is always greater than the air pressure at the altitude.

2.Relationship between barometric pressure and temperature:

Generally speaking, the higher the temperature, the faster the atmospheric expansion and rise due to heating, and the lower the air pressure, so in most cases, the hot area is low pressure and the cold area is high pressure, such as the equatorial low pressure belt and the polar high pressure belt.

However, in addition to being related to the temperature experience, as long as the airflow rises somewhere, the ground is low, for example, the subpolar region is due to the meeting of cold and warm airflow, the airflow rises, and the low pressure is formed, and the area where the subtropical high is located is quietly stuffy due to the accumulation of high air pressure, which causes the airflow to sink, but forms high pressure in the hot place, which is formed by dynamic reasons.

This is what I learned in high school.

When the temperature cools, the pressure of the gas decreases, because the pressure of the gas is proportional to the amount of gas (n) and the temperature of the gas (t), and when the temperature of the gas drops, the corresponding gas pressure decreases.

Meaning of barometric pressure:

1.Air pressure generally refers to the hydrostatic pressure exerted by the gas to a certain point, and the gas pressure is caused by the continuous and irregular impact of a large number of gas molecules on the container wall.

2.According to the ideal gas law pv=nrt: the magnitude of the gas pressure is proportional to the amount of the gas (n), the temperature of the gas (t), and inversely proportional to the volume of the gas (v) r is the universal gas constant, which is about.

The glass tube about 1m long and closed at one end is filled with mercury, the nozzle is blocked, and then inserted inverted in the mercury tank, when the finger that is plugged is released, the mercury level in the tube drops a little and then it does not fall, and the height difference between the mercury surface inside and outside the tube is 760mm The reason why there is a 760mm high mercury column in the tube is precisely because of the existence of atmospheric pressure From the characteristics of liquid pressure, it can be seen that the pressure on the surface of the liquid in the mercury tank should be equal to the pressure at the same height as the 760 mm mercury column in the glass tube The pressure on the surface of the liquid in the mercury tank is atmospheric pressure, because the mercury column in the glass tube is vacuum, and it cannot be affected by the atmospheric pressure, and the pressure in the tube can only be generated by the mercury column at a height of 760mm Therefore, the atmospheric pressure is equal to the pressure generated by the mercury column at a height of 760 mm Normally, the common units that express the pressure of the gas are Pascal, millimeter mercury column (millimeter mercury), centimeter mercury column (centimeter mercury), standard atmospheric pressure, and their symbols are pa, mmhg, cmhg, atm

All other things being equal, the pressure of the gas becomes lower when the temperature cools.

pv = nrt

The ideal gas equation of state, also known as the ideal gas law and the universal gas law, is an equation of state that describes the relationship between pressure, volume, quantity of matter, and temperature of an ideal gas in equilibrium. It is based on empirical laws such as Boyle-Mariott's law, Charlie's law, Guy-Lussac's law, etc.

The equation is PV = NRT. There are 4 variables in this equation: p is the pressure of the ideal gas, v is the volume of the ideal gas, n is the amount of gaseous substance, and t is the thermodynamic temperature of the ideal gas; There is also a constant:

r is the ideal gas constant. As can be seen, there are many variables in this equation. Therefore, this equation is known for its many variables and wide range of applications, and it is also approximately applicable to air at room temperature and pressure.

It is important to note that it is incorrect to equate the ideal gas equation with the Kraberon equation. The general Kraberon equation refers to the equation dp dt=l (tδv) that describes phase equilibrium. Although the ideal gas law was discovered by Claberon, the ideal gas equation of state is not called the Claberon equation in the world.

The pressure of a gas is closely related to temperature: when the temperature rises, the pressure increases when the volume remains constant; And when the temperature decreases, the pressure decreases gradually.

Let's explain it microscopically: when the volume is constant, the density of the molecules is constant. In this case, when the temperature increases, the average kinetic energy of the molecules increases, and the pressure of the gas increases.

The degree to which the motion of molecules is affected by temperature is not the same, just like the specific heat capacity.

Hello, glad to answer for you! Temperature reflects how violently the microscopic particles are moving. Solids, liquids, and gases are all made up of a large number of microscopic particles.

For the same kind of object, the higher the temperature of the object, the more intense the motion of the microscopic particles that make up the object. For example, ice, water, and water vapor belong to the same substance, and the temperature gradually increases from ice to water to water vapor, indicating that the particles that make up them are also moving more and more violently.

This is also the reason why the rate of forward and reverse reactions decreases after cooling. The endothermic reaction is inherently required to absorb the surrounding heat, and it naturally slows down when it cools down, and to a greater extent than you say.

The reason why the temperature becomes smaller is that work is done externally.

When the temperature of the system decreases, the internal energy of the system decreases and the energy is transferred. There are only two ways to transfer the energy of a system: work done and heat transfer.

Because it is adiabatic, there is no possibility of heat transfer; Only the external work of the system will decrease (under the conditions of this problem), and when the external work is done on the system, the internal energy of the system will increase (under the conditions of this problem).

The volume of the gas expands, and the work done externally means that the gas does positive work on the container wall.

At this time, the internal energy of the gas decreases.

Whereas, the internal energy of an ideal gas is determined by the kinetic energy of the gas molecules.

The average kinetic energy of a molecule is again the definition of the temperature of the gas.

When the kinetic energy decreases, the temperature drops.

In fact, in principle, the speed of the pulldown does not affect the final temperature.

But in reality, the gas is not isolated from the outside world.

The pull-down slows down, the gas exchanges heat with the outside world (also heat transfer), and the temperature drops insignificantly.

Therefore, it pulls down quickly, so that the temperature drops rapidly.

Adiabatic means that the internal energy remains unchanged, while the constant external pressure expansion is external work, and it is necessary to convert the molecular kinetic energy into potential energy, that is, external work, and the molecular kinetic energy is small, and the temperature is reduced.

The temperature will decrease, because: adiabatic means that the internal energy remains unchanged, and the constant external pressure expansion is the external work, and the molecular kinetic energy needs to be converted into potential energy, that is, the external work is done, and the molecular kinetic energy is small, and the temperature is reduced.

Let's see what others have to say.

I didn't know about it, but I understood it after the two big guys answered. I'll use the formula and summarize what they mean, q=δu+w. w is the work of expansion; δu is the thermodynamic energy; q is the heat.

Adiabatic q=0;

The expansion indicates that the working fluid is externally worked, so w 0;

u=cv（t2-t1）。You can refer to engineering thermodynamics;

0 = W (greater than zero) + δu

It is not difficult to see δu 0, i.e., cv(t2-t1)<0,t2

For the same volume change, the decrease of pressure p in the system during isothermal expansion is completely caused by the band and decrease of the system density.

For adiabatic expansion processes, the decrease in system pressure is caused by a combination of a decrease in the density of the sand and a decrease in temperature. Therefore, the pressure changes faster in the adiabatic process than in the isothermal process.

Answer] C [Answer Analysis] Test question analysis: The temperature is unchanged, indicating that the average molecular kinetic energy of the gas is unchanged, and options A and B are wrong; A decrease in volume indicates an increase in the number of molecules in a unit volume of the gas; The increase in pressure indicates that the number of collisions between gas molecules per unit area of the container wall per unit time increases, so option C is correct and option D is wrong. Test Center:

This question tests the understanding of the microscopic interpretation of gas parameters.