What is the relationship between temperature and pressure at the same temperature and pressure?

The thermal effect refers to the heat absorbed or released by a material system when it only does expansion work in a physical or chemical isothermal process. According to the different properties of the reaction, it is divided into heat of combustion, heat of formation, heat of neutralization, heat of dissolution, etc. In this case, the thermal effect refers to the heat of combustion, which can also be referred to as the heat of formation.

Heat of generation 1Heat of formation of compounds: The thermal effect of constant pressure reaction of a 1mol compound produced by the synthesis of stable elements is called the heat of formation of the compound, also known as the enthalpy of formation.

The enthalpy of the most stable element at all temperatures is specified to be zero, so the enthalpy change of the reaction of the compound formed from the stable element is the relative enthalpy of the compound - the heat of generation. In order to carry out unified calculation and comparison, the standard heat of formation is often used, that is, at a specified temperature, at 101325Pa, the heat of reaction when a 1mol compound is formed from a stable element, which is the standard heat of formation of the compound at this temperature, which is represented by symbols. Caution when using:

It is customary to use the numerical value at 25 o c, which is represented by the symbol . It is also sometimes used directly to represent the standard generation heat at 25oC.

2.Thermal effect of chemical reaction: The thermal effect of chemical reaction at constant temperature and pressure is equal to the sum of the heat of formation of the product minus the sum of the heat of formation of the reactant, i.e.

Product — reactant.

or product-reactant.

Heat of combustion. The thermal effect of 1 mol of a substance when it is completely burned under specified conditions is called the heat of combustion of that substance. The so-called complete combustion refers to the fact that the product is in a stable aggregation state, such as C becomes CO2 (G), H becomes H2O (L), S becomes SO2 (G), N becomes N2 (G), Cl becomes HCl aqueous solution, etc.

The heat of combustion of a substance can be found in the manual of thermodynamics, and most of the manuals list the heat of combustion of a substance under 25 o c and 101325 pa, which is called the standard heat of combustion of the substance, which is denoted by .

The heat of reaction can also be calculated from the heat of combustion

Reactants — Products.

Since the state of sulfur is unclear at the same temperature and pressure, it is impossible to judge.

The thermal effect refers to the amount of heat generated.

The temperature and pressure are the same, but the state of the sulfur is not explained, so it is impossible to judge, so D is chosen. It doesn't matter if it's in air or oxygen.

The heat effect is the meaning of heat of reaction.

All chemical reactions are actually rearranged and combined atoms or clusters of atoms, and there will be energy changes during the rupture of old bonds and the formation of new bonds, which is the thermal effect of chemical reactions.

At the same temperature and pressure, the thermal effect is equal to the increment of the enthalpy of the system, which is denoted by the symbol h. A negative value indicates that the process is exothermic. The lower the h value, the more heat is released from the reaction, and the higher the h value, the less heat is released from the reaction.

At the same temperature and pressure, the total energy of 32 grams of sulfur is equal, because sulfur is completely burned in pure oxygen to emit a bright blue-purple flame, and sulfur is completely burned in air The flame is faintly light blue, so sulfur consumes more energy for luminescence in pure oxygen than in air, so sulfur reacts to release less heat in pure oxygen than in air, and the absolute value of δH1 is less than the absolute value of δH2, that is, δH1>δH2 choose b

Ideally, temperature and pressure are related.

The ideal gas equation of state, pv=nrt p is the pressure, t is the temperature.

From the equation, it can be seen that the pressure is proportional to the temperature, the lower the temperature, the smaller the pressure, and the higher the pressure, the higher the temperature.

There is no necessary relationship between pressure and temperature, the higher the temperature under the same volume, the greater the pressure; It cannot be said that there is a relationship between pressure and the transformation of the state between objects.

If in a confined space, liquid water absorbs heat and vaporizes, the pressure increases in the process of becoming vapor; In an open container, the liquid water is heated and condensed into solid ice, and the pressure remains the same, but the volume increases.

Simply saying that water vapor and ice are not comparable, and the space in which they are located is related, in the case of a closed container, the water vapor is exothermic and condenses into ice, and the pressure in the container is reduced, and vice versa.

Within atmospheric pressure, the pressure is related to the temperature.

Factors influencing atmospheric pressure.

Temperature: The higher the temperature, the stronger the movement of air molecules and the greater the pressure.

Density: The higher the density, the greater the air quality and the greater the pressure per unit volume.

Altitude: The higher the altitude, the thinner the air and the less atmospheric pressure.

The pressure of the liquid is related to the depth and density of the liquid, and not to the historical mass of the liquid.

Liquid pressure is caused by gravity and fluidity.

Factors influencing the pressure of the liquid: depth, density of the liquid (independent of the shape of the container, mass volume of the liquid).

The methods of increasing the pressure are: increasing the pressure under the condition that the force area remains the same or decreasing the force surface with the same pressure. The methods of reducing the pressure are: reducing the pressure under the condition that the force area remains the same or increasing the force area when the pressure is not the same.

The relationship between pressure and force and force area is:

Where: p stands for pressure; f represents the vertical force (pressure); s represents the stressed area;

Based on the above formula, the following formula can be derived:

This formula is used to calculate the pressure of a liquid, where p denotes the pressure; Indicates the density of the liquid; g and is numerically equal to the acceleration of gravity; h indicates the depth of the liquid.

The choice A and C are derived from the title: Co and O2 of the same volume at the same temperature and pressure contain the same number of molecules, that is, the amount of matter is the same, and both are 1.

2co+o2=2co2

A The volume ratio of Co and O2 participating in the reaction is 2 to 1

Correct, the amount of CO2 molecules formed by b is two-thirds of the number of molecules of the original gas.

False, because the original gas is 1:1, and there is 1 2 oxygen left, therefore, the CO2 generated is 1, which is 1 2 of the total amount of the original gas

c The volume of the gas after the reaction is three-quarters of the original.

Correct, because there is 2 in the original, carbon dioxide 1 is generated at the end, and oxygen 1 2 is left, so the volume of the gas after the reaction is three-quarters of the original).

The ratio of the number of C and O atoms in the gas after the reaction is one to two.

False, the number of atoms before and after the reaction does not change c:o=1:3).

The answer is a, c; The number of CO2 molecules generated is one-half of the number of original gas molecules; The ratio of the number of C and O atoms in the gas after the reaction is one to three.

The same gas has the same number of molecules, 2CO+O2=2CO2 In the reaction formula, 2CO and 1 O2 react, the answer is A.

The relationship between air pressure and temperature.

In general, if there are no other factors, the higher the temperature, the lower the air pressure, because the higher the temperature, the air near the ground is heated and expands and rises, resulting in a decrease in air density and a decrease in air pressure. Conversely, the air pressure rises. If it is affected by other factors, it is necessary to analyze the specific problem on a case-by-case basis.

For example, the air pressure decreases as the sea level increases.

The formula is available p= rt

p is the absolute pressure of the gas (pa), t is the temperature of the gas (k), r is the gas constant (r = 287j (kg*k) for dry air) and is the density of the gas (kg m 3).

The relationship between temperature and pressure within the most powerful star of the vast universe.

PV t=r (constant).

The increase of temperature and pressure is established under the premise that the volume v remains unchanged. Under the premise that p does not change, the volume also becomes larger as the temperature increases. If t and v are not proportionally larger, then p is likely to become larger and smaller.

Temperature is a representation of the kinetic energy of microscopic particles, and pressure is the time average of the impulse of microscopic particles on the wall

p=2/3*n*e

e=3/2*kt

For liquids and solids, the pressure is independent of the temperature.

For an ideal gas of a certain mass, p t = a constant quantity in an isochoric change.

Generally speaking, we think that the way to increase pressure (increase pressure) is to flush in the gas or reduce the volume. As long as one of these three changes, then it will inevitably cause the change of the purity of the other two, which is a process of moving towards equilibrium, and finally reaching equilibrium.

As the temperature increases, the volume of the gas increases; The temperature decreases and the volume of the gas decreases.

The pressure increases, and the volume of the gas decreases; Reducing the pressure and increasing the volume of the body of the high air pants.

The two influence each other, and it is impossible to determine which factor is more effective.

The ideal gas satisfies this equation: PV=NRT, but requires specific temperature and pressure.

n is the amount of substance of the gas.

r is the ideal gas constant.

t is the temperature of the gas, p is the pressure of the gas, and v is the volume of the gas.

Depending on your conditions in the atmosphere (constant pressure), if the volume becomes larger and the pressure still increases, then the volume will definitely become larger.

If the volume and temperature increase at the same time, then it is still difficult to judge the change in pressure, and it is impossible to judge whether the volume is a stronger factor or a stronger temperature factor.