Whether the enthalpy increases or decreases, and the enthalpy becomes less than 0 to reduce the temp

The total energy of the matter in this system increases, and the enthalpy in the system increases! (from a chemical point of view).

But the temperature of the chemicals in the system decreases, and the enthalpy in the system decreases!

In the end, the enthalpy change did not increase or decrease!

h=q+w so the enthalpy change is related to heat and work, heat refers to the heat exchanged with the environment, work refers to the work done to the environment or the environment to the system, of course, it is related to temperature and pressure.

The physical meaning of enthalpy can be understood as constant pressure and under the special condition of doing only volume work, q=δh, that is, the heat change of the reaction. Because it is only under this condition that enthalpy exhibits its properties. For example, if a substance is heated at constant pressure, the temperature of the substance increases after heat absorption, and δh>0, so the enthalpy of the substance at high temperature is greater than its enthalpy at low temperature.

For example, for an exothermic chemical reaction at constant pressure, δH<0, so the enthalpy of the product is less than the enthalpy of the reactant. You're an independent system, and it stands to reason that the enthalpy is generally constant.

Enthalpy is the thermokinetic energy, if the chemical reaction is endothermic, then the total thermokinetic energy decreases and the enthalpy decreases.

There is a principle in chemistry that a chemical reaction is possible if and only if δh-tδs < 0. where δh is the enthalpy change of the reaction, t is the thermodynamic temperature, and δs is the entropy change of the reaction.

The enthalpy change is equivalent to the thermal effect of the chemical reaction, in other words, if the reaction is endothermic, the total enthalpy of the system increases, and if the reaction is exothermic, the total enthalpy of the system decreases. However, this conclusion only applies to reactions at certain temperatures. For isolated systems, upstairs is the answer.

The enthalpy change does not necessarily increase as the temperature increases.

Learn Physics:1. Explore more when encountering problems. Physics, I feel that there are always a lot of new problems, how did this formula come about? Why do we need to use such a public delay to solve the problem?

There are other methods, why did you choose this one? If you are such an exploratory person, then congratulations, as long as you are willing to specialize, you will definitely be able to learn physics well, because the most needed students in physics class are students with the spirit of exploration and specialization.

2. Learn to associate memory. In fact, no matter which discipline Yuanliang has, the knowledge points and knowledge points are all interconnected, one after another knowledge points, and one bit after another section can be linked to each other, and one knowledge point can be associated with another knowledge point. This kind of grafting of knowledge points will help you grasp the knowledge faster, associative memory is a very practical memory method, it is recommended that you are eager to learn, you can try it.

dBecause the enthalpy change is less than 0, the positive reaction is exothermic. The root tour is suspected according to the principle of Le Chatre.

When the temperature is raised, the equilibrium moves in the direction of the temperature decrease, and the endothermic pin grinds in the direction of the counterreaction, so the equilibrium constant.

Smaller. As the temperature increases, the rate of both forward and reverse reactions increases, but here the rate of reverse reaction increases more, resulting in a reverse shift of equilibrium.

Neither of these is concentration-independent.

1. The relationship between δh and t: the enthalpy of the reaction will change with temperature. Under isobaric conditions, the rate of change of enthalpy with temperature i.e. ( h t)p=cp i.e. isobaric heat capacity Then ( δh t)p=δcp i.e., the rate of change of enthalpy change with temperature at isobaric pressure is the change value of isobaric heat capacity The change value of isobaric heat capacity is generally obtained by experiment.

2. The relationship between δH and P: for ideal gases, H is only determined by temperature, and ΔH should also be a constant value at a constant temperature, and for non-ideal gases, ......δH = A(1 vm,1 - 1 vm,2)+δPvm) A is the parameter in the Van der Waals gas equation, and vm is the molar volume refers to the state before and after the volume change (the volume change can also be found by isothermal conditions).It's a bit messy, isn't it.

3. The relationship between δs and temperature and pressure: it is also related. But the formula is difficult to express, basically the relationship between δs and pressure seems to be related to the coefficient of expansion, and the relationship between δs and temperature is based on the original δs and adds a term that is integrated according to the number of species, temperature changes, and molar isobaric heat capacity before and after the reaction......

Neither of these is concentration-independent.

1. The relationship between δh and T: the enthalpy of the reaction.

It will change with temperature. The rate of change of enthalpy with temperature under isobaric conditions.

i.e. (h t)p=cp

i.e. isobaric heat capacity.

Then ( δh t)p = δcp

That is, the change rate of enthalpy change with temperature during isobaric pressure is the change value of the heat capacity of isobaric tung resistance.

The value of the change in isobaric heat capacity is generally obtained by experiment.

2. The relationship between δh and p: for ideal gases.

h is determined only by temperature.

ΔH should also be a constant value at a constant temperature.

For non-ideal gas ......δh=a(1/vm,1

1/vm,2)+δpvm)

A is the parameter in the Van der Waals gas equation and vm is the molar volume.

It refers to the state before and after the volume change (the alluvial change of the body wheel can also be found by the isothermal condition and the change in the pressure of the Changshu strength).It's a bit messy, isn't it.

3. The relationship between δs and temperature and pressure: it is also related. But the formula is difficult to formulate.

Basically. The relationship between s and the pressure seems to be the coefficient of expansion.

Relate. The relationship between δs and temperature is based on the original δs and an ...... is integrated according to the number of species, temperature change, and molar isobaric heat capacity before and after the reaction

Doing work on an object or raising the temperature of the object can increase the enthalpy of the object. By doing work on the object, or conducting heat to the object, the internal energy of the object can be increased, the thermal motion of the molecules will be more intense, and the value of the enthalpy of the substance will also increase.

Enthalpy is a function of state, that is, the value of enthalpy is determined when the state of the system is fixed.

The definition of enthalpy (enthalpy has no actual physical meaning, but it has operational significance. Here's what it looks like: H = U + PV [enthalpy = flow internal energy + work of propulsion].

where u represents thermodynamic energy, also known as internal energy, that is, all the energy inside the system;

p is the pressure of the system, and v is the volume of the system

Heating or pressurization. enthalpy, is a concept introduced by considering the combination of physics and mathematics, especially calculus

1. Heat energy is only a function of the process, only a trace amount of accumulation, which can be integrated, but not differentiated;

2. The internal energy of the system will be changed if the system is external heat or heat is absorbed from the outside;

That is, the change in internal energy can occur in the form of heat energy;

Similarly, changing the internal energy of the system can also do work on the system, including mechanical work and non-mechanical work.

In this way, the concept of enthalpy was born, which has the property of a state quantity, which can be differentiated, can be integrated;

It can be exchanged externally in the form of heat energy, and it can exist in the state in the form of internal energy.

The concept of enthalpy, so far, has been distorted and misled all the time in our teaching, and our teachers, who are very arrogant and reckless, are everywhere.

Knowing this, it is easy to understand the way in which enthalpy increases:

1. The most typical heat transfer to the system is the heating up; The enthalpy can also be increased without heating;

2. To do work on the system, most people only understand pressurization, which is just mechanical work;

In physics, there are many forms of work, such as electropolarization and magnetization.

There are also many chemical methods, excitation, ionization, ionization, and photosynthesis

Photosynthesis can increase the enthalpy.

The more heat is released, the greater the absolute value of h.

But the exothermic reaction h0, so is equivalent to the magnitude of a comparatively negative number.

The greater the absolute value of the negative number, the smaller it is.

The unit of enthalpy change kj mol in each mol refers to the reaction per mol, and the so-called reaction per mol is the reaction represented by the chemical equation written before the enthalpy change value, that is, the reaction is 1 mol reaction.

If it is written as H2+1 2O2=H2O, it means that 1molH2 reacts with 1molH2O to form 1mol; If it is written as 2H2+O2=2H2O, it is a 1mol reaction between 2molH2 and 1Molo2 to generate 2MoL2O. So the enthalpy change is different, but a 2-fold relationship.

The mol in enthalpy change unit refers to the reaction per mole.