A small question about the thermochemical equation 50

It should be written with an equal sign.

Principles of Thermochemical Equation Writing (from left to right).

Compared with ordinary chemical equations, the following points should be paid attention to when writing thermochemical equations, in addition to complying with the requirements for writing chemical equations:

1 The stoichiometric number before the chemical formula of each substance in the thermochemical equation only indicates the amount of the substance of the substance, not the number of molecules or atoms of the substance. Therefore, stoichiometric numbers are in units of "mol" and the value can be either a decimal or a fraction.

2 The aggregation state of reactants and products is different, and the heat of reaction h is also different. Therefore, it is necessary to indicate the aggregation state of the substance, g gaseous, l liquid, s solid, aq solution, since the aggregation state of the substance has been indicated, and and is not used in the thermochemical equation.

3 The heat of reaction h is related to the measurement conditions such as temperature, pressure, etc. Therefore, when writing thermochemical equations, the determination conditions of h should be indicated. If it is not indicated, it means that it is measured at 298K and 101325Pa.

4 Write the "+" and " " values and units of h to the right of the chemical equation written, separated by a space between the equation and h. If it is an exothermic reaction, h is " " if it is an endothermic reaction, h is "+" Since h is related to the amount of material that the reaction is completed, the stoichiometric number must correspond to h. When the reaction proceeds in reverse, its heat of reaction is equal to the value of the heat of reaction of the positive reaction, and the sign is opposite.

The unit of h is kj mol.

According to the syllabus of the college entrance examination! The paper is judged like that, and points will be deducted if you write it wrong!

In general, the inorganic reaction equation is written with an equal sign, and the organic reaction equation is written with an arrow.

Organic is a single arrow, and inorganic is an equal sign, just like a chemical equation

This is generally based on your textbook.

What is a textbook is the foundation of the exam, and it cannot be fully trusted.

Thermochemical equations are generally written with an equal sign, but if it is a reaction in which organic matter participates, arrows are written.

Organic reactions, reversible reactions write arrows.

Other reactions are written with equal signs.

1.Thermochemical equations do not contain reaction conditions. There is no conclusive conclusion whether it is written correctly or not, but it is not written in all the materials of the secondary school.

2.Arrows are generally used in organic equations, because most organic reactions are complex and have many side reactions. However, from the perspective of combustion, there is not much difference between organic matter and inorganic, so there are cases where an equal sign is used.

However, I personally recommend using arrows, so that there will be no problem in the college entrance examination.

According to the chemical reaction equation and the conservation of energy, h1+h2=h3-q gives that the nh bond energy should be.

I haven't done it for a long time, and I'm not sure if it's correct.

Note that 2H2O is δH=+, and similarly, 2H2O δH=;

When liquid water becomes gaseous water, it absorbs heat; Pick 2;

1 mol of water is 18 g (1 mol of particles collectively contains the same number of particles as the number of carbon atoms it contains).

When 1g of liquid water becomes gaseous water: (1 18)mol (The key is the number in the equation, pay attention to it to understand the choice of 3, otherwise the wrong choice is c.)

Solution: 2H2O(L)=2H2(G)+O2(G) ΔH=+ 2H2(G)+O2(G)=2H2O(G) ΔH= + 2H2O(L)=2H2O(G) ΔH=88kJ mol That is, 36g of liquid water becomes gaseous water and absorbs heat of 88kJ

So when 1g of liquid water becomes gaseous water, it absorbs heat 44 9 . So choose D

Think about the evaporation of water, is it to absorb heat?

1g h2o=1/18mol h2o

From Hess's theorem2mol H2O (l) H2O(G) δH=δ Q=(ΔH2)*(1 18).

Calculate the amount of 2m0l first.

That is, 1 type 1 and 2 types.

2m0l=36g

i.e. what is sought = (1 102) 36

The one-mole reaction in the thermochemical reaction equation is related to the specific equation.

For example: for:

For the reaction of 2CO+O2---2CO2, one mole of the reaction should be inverse: 2mol of CO reacts with 1mol of O2 to produce 2mol of CO2, and for the reaction of CO+1 2O2---CO2, one mole of reaction means: 1mol of CO reacts with O2 to produce 1mol of CO2.

For the first reaction, the heat of reaction of 1mol is exactly twice that of the second reaction, which is 1mol of reaction.

The thermochemical equation must correspond to a specific equation (that is, to have a specific ratio), and the state of the species (gas?). Liquid? Solid? Solution? Pressure? Temperature? Otherwise, there is no point in raising the thermochemical equation.

This sentence is understood in this way, 1 mole of carbon, reacts with excess oxygen! That is to say, carbon is finite, oxygen is excessive....The 1mol is limited to the amount of carbon....

One mole of CO is fully oxidized by oxygen! That is, one mole of material is completely burned to form a stable compound!

The heat of combustion is the heat emitted by 1 mole of hydrogen.

The heat of neutralization is the heat released by the production of 1 mole of water.

The heat of reaction is the h of the thermochemical equation

I can be a freshman, hehe.

In the heat of combustion, one reactant is combustible, the other is oxygen, and the coefficient of combustible matter must be one, the neutralizing heat is only the heat released by strong acid and strong base to generate 1 mole of water, and the heat of reaction is a coefficient of several can be, more casual, no strict requirements!

1. The chemical reaction formula that represents the heat emitted or absorbed by the chemical reaction is the thermochemical equation!

2. Note to the book:

The first is a chemical equation (but the coefficient can be a fraction), and the second is that each substance must be marked with a "state" (g or l or.) below. s), and thirdly, h or —)x kj mol,the value of x must be indicated after the chemical equation in relation to the magnitude of the coefficient!

3. For example: 2H2(G)+O2(G)=2H2O(G) H=-484kJ mol

h2(g)+1/2o2(g)=h2o(g) △h=-242kj/mol

Less conditional, he should tell you the heat of combustion of hydrogen.

Assuming that the heat of combustion of hydrogen is mol, 2H2(L)+O2(L)=2H2O(G) H -475kJ mol h (

Lack of conditions, such as the heat of combustion of hydrogen.

It is through the addition and subtraction of these thermochemical equations that the required equation is obtained.

From the third equation, it can be seen that 3feO(S)+CO2(G)=Fe3O4(S)+Co(G) H=-19kJ mol ..1)

From the second equation, it can be seen that 2Fe3O4(S) + CO2(G) = 3Fe2O3(S) + Co(G) H=+47kJ mol .2)

And the first equation: Fe2O3 + 3Co (G) = 2Fe (S) + 3 Co2 (G) H = -25kJ mol ...3)

From 2*(1) +2) +3*(3), remove the same substance on both sides of the equal sign, and we get:

6feO(S)+6Co(G)=6Fe(S)+6CO2(G), while the corresponding H=2*(-19)+47+3*(-25) = -66kJ mol

Eliminate 6 to obtain: FeO(S)+Co(G)=Fe(S)+CO2(G) H = -11kJ mol