High sophomore chemistry Heat calculation of reactions

Convert C+O2 ==CO2 -394 kg mol to CO2 ==C+O2 394 kg mol Synapid C+1 2 O2 ==Co -111 kg mol....Eq. 1 yields co+1 2 o2==co2 283 kg mol, and then H2+1 2 O2==H2O -242 kg mol....Equation 2 is converted into H2O==H2+1 2 O2 242kg mol According to Equation 2, it takes 242kg of heat per mole of water to decompose into one mole of hydrogen and 1 2 moles of oxygen

According to Eq. 1, the reaction of carbon monoxide and 1 2 moles of oxygen releases 283 kg of heat).

Synonym 1 and Equation 2 can be obtained.

CO+H2O===CO2+H2 131kg mol If it is an answer, it can not be written in parentheses.

I need to give some data.

naohaq）+1／2h2so4（aq）=1／2na2so4（aq）+h2o（l）；δh＝－57．3kj

According to the data given, an excess of H2SO4 is exactly 1molNaOH reaction, which emits heat =

ch4(g)+2o2(g)==co2(g)+2h2o(l);

h=-893kj/mol

Found: The heat of reaction that produces liquid water,)

16g...893kj

x...x＝1．02g

If you really want to calculate the generation of gaseous water, you also need to know the heat of vaporization of water, which is more troublesome to calculate,)

Calculation of heat of reaction:1. Measured by experiment:

According to the specific heat. The formula is calculated: q=cm t, and then according to the chemical reaction equation.

The heat of reaction is found by q.

2. The amount of heat of reaction and reactant substances.

proportional. 3. Calculate the heat of reaction by using bond energy

Usually people take apart 1mol of a certain chemical bond.

The energy absorbed is regarded as the bond energy of the chemical bond, which is usually expressed in e in kj mol.

Method: H = e (reactant) — e (product), i.e., the heat of reaction is equal to the difference between the sum of the bond energies of the reactants and the sum of the bond energies of the products.

Such as the reaction H2 (G) + Cl2 (G) Manuscript Chang 2HCl (g).

h=e（h-h） +e(cl-cl） -2e（h-cl）。

4. Calculate the total energy of reactants and products

h = total energy of the product - total energy of the reactant.

5. Calculated according to the heat of combustion

The heat emitted by the combustion of a substance q=n (combustible) The heat of combustion of the substance.

6. According to Gaisce's law.

Perform calculations: The heat of reaction of a chemical reaction is the same regardless of whether it is completed in one step or in several steps; That is to say, the heat of reaction of the chemical party is only related to the beginning and end states of the reaction, and has nothing to do with the reaction pathway. That is, if a reaction can be carried out in several steps, then the sum of the heat of reaction of each step of the reaction and the completion of the reaction in one step.

The heat of reaction is the same.

Calculation of the heat of reaction: 1. Measured by experiment: calculated according to the specific heat formula: q=cm t, and then the heat of reaction is calculated by q according to the chemical reaction equation.

2. The heat of reaction is proportional to the amount of each substance of the reactant.

3. Calculate the heat of reaction by using bond energy: Usually people regard the energy absorbed by disassembling 1mol of a chemical bond as the bond energy of the chemical bond, and the bond energy is usually expressed by e, the unit kj mol. Method:

h = e (reactant) — e (product), i.e., the heat of reaction is equal to the difference between the sum of the bond energies of the reactants and the sum of the bond energies of the products.

5. Calculation according to the heat of combustion: the heat released by the combustion of the substance Q=n (combustible trousers) The heat of combustion of the substance.

6. Calculate according to Gaisce's law: whether the chemical reaction is completed in one step or several steps, the heat of reaction is the same; In other words, the heat of reaction of the chemical response is only related to the beginning and final states of the reaction, and has nothing to do with the reaction pathway. That is, if a reaction can be carried out in several steps, the sum of the reaction heats of each step of the reaction is the same as the heat of reaction when the reaction is completed in one step.

The formula for calculating the heat of reaction is: qp= u+p v= u+rt vb

where u u final state - u initial state u reaction product - u reactant, where vb(g) = n(g) mol, that is, 1mol reaction occurs, the difference between the total number of product gas molecules and the total number of reactant gas molecules.

From this equation, it can be seen that for a specific chemical reaction, whether the isobaric thermal effect is equal to the isochoric thermal effect depends on whether the total number of gas molecules changes before and after the reaction. If the total number decreases, for the exothermic reaction qp > qv, the isobaric process releases more heat than the isochoric process.

If the total number of gas molecules increases before and after the reaction, for the exothermic reaction, qp < qv, and part of the energy released by the reduction of internal energy before and after the reaction will be transferred to the environment in the form of work, and the heat released is less than the isochoric heat effect. Similarly, an analogy can be obtained for endothermic reactions.

In general, the more stable the matter, the lower the energy it has; The more unstable the matter, the higher the energy it has. If the total energy of the reactants in a chemical reaction is greater than the total energy of the product, then the reaction is exothermic and h<0Otherwise, it is an endothermic reaction, h>0

Heat of reaction and matter energy relationship: h = total energy of the product - total energy of the reactant; It is also known that the greater the sum of the bond energies of a substance, the more stable it is, and the lower the energy it has.

Relationship between heat of reaction and bond energy h = sum of bond energies of reactants - sum of bond energies of products.