Is the reaction rate the same for different reaction levels?
The reaction order was closely related to the reaction rate. Under normal circumstances, the reaction rate would be different depending on the reaction order. The reaction order reflected the relationship between the reaction rate and the concentration of the reagents. It was the sum of the powers of the concentration of the various reagents in the rate equation. Different reaction orders meant that the concentration of the reagents affected the reaction rate in different ways and degrees. For example, the reaction rate of a zero-order reaction had nothing to do with the concentration of the reagent, the reaction rate of a first-order reaction was proportional to the first power of the concentration of the reagent, and the reaction rate of a second-order reaction was proportional to the second power of the concentration of the reagent. However, the reaction rate was also affected by other factors, such as temperature, catalyst, etc. Under certain conditions, even if the reaction order was different, it was possible that other factors affected the reaction rate so that the reaction rate of different reactions was the same at a certain time. However, this was a special case and not the normal case. Read more exciting novels for free
The Determination of Reaction Rate and Reaction Constant
The chemical reaction rate represented the speed of the chemical reaction, which was the rate of change of the reaction progress with time or the reaction progress of the chemical reaction in unit time and unit volume. The average reaction rate was the decrease of the concentration of the reagent or the increase of the concentration of the product in unit time. The instantaneous reaction rate was the limit of the average reaction rate that approached zero. The reaction rate constant represented the chemical reaction rate at a unit concentration. It was independent of the concentration, but it was affected by factors such as temperature, catalyst, and solid surface properties. Usually, the larger the reaction rate constant, the faster the reaction would proceed. There were two common methods to measure chemical reaction rates: chemical and physical methods. The chemical method used chemical analysis to directly measure the change in the concentration of the reagent or product over time to obtain the chemical reaction speed. However, the chemical analysis speed might not be able to keep up with the reaction speed and affect the measurement results. However, it could provide an absolute concentration value. The physical method was more extensive and convenient. It was to determine the reaction speed based on some physical properties that changed with the reaction, such as the pressure method, the distension meter method, or the volume method; the optical rotatory method, the interference method, the chromicity method, and the spectrophotosity method; and the electrical property method, such as the conductivity method, the potential method, the polarography method, the dielectrical constant method, and the mass spectrum method. As for the determination of the reaction constant, for example, in the experiment of determining the rate constant of the fading reaction by the method of the catalyst, based on the principle of the catalyst kinetic method, the reaction system of the fading reaction of the Evans Blue by the reaction of the potassium bromate under the action of the NaNO3 was proposed. The corresponding chemical reaction rate constant was calculated by measuring the change of the absorption of the reaction system at different initial concentration and temperature. In terms of specific operations, the stock solution of the relevant reagents was first prepared, and then the reagents were added into the color-measuring tube according to a certain order and dosage. The timing and volume were started, and then the absorption curve was measured. The reaction constant was determined by preparing reaction solutions of different compositions, adding the solution after reacting for a period of time to stop the reaction, and taking a sample to measure the absorption curve. Finally, the concentration of other components was maintained at a constant temperature, and the change of the light absorption with time when different amounts of the solution of bromate or the solution of NaNO3 were measured, as well as the change of the light absorption with time when the specific amount of the solution of NaNO3 was measured at different temperatures. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
First Order Reaction Formula of the Reaction Rate
The first-order reaction rate equation was: r = -dt/dt = kc, and its integral form was: Where, a is the concentration of the reagent at the beginning of the reaction, c is the concentration of the reagent at time t, and k is the rate constant. The unit is the negative power of the time unit, such as s^{-1}, min^{-1}, h^{-1}, d^{-1}, etc. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The Reaction Rate of the Reaction of Keto and Bihydrogen Sulphite
In the addition reaction of the carbonyl-like group of the acid, the reaction rate was different. Propional reacted the fastest with bisulfuric acid, followed by Cyclohexuron, methylethyluron, and dibenzone. Among the alkahedes, the reaction rate of the addition of formalin to the nucleus was the fastest. Because the hydrogen atom attached to the carbonyl-group was the smallest, the steric hindrance was the smallest, so the reaction was the fastest. Aldes, fatty methyls, and cycloketones with less than eight carbon atoms could undergo an addition reaction with saturated water-based bisulphite solution (about 40%). The reaction rate of different alkyls and methyls was different, which was related to the atoms or groups connected to the carbonyls. The smaller the steric hindrance caused by the atoms or groups, the faster the reaction rate. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The conversion rate of the same reaction expressed by different substances
If there was more than one reagent, the conversion rate calculated according to different reagents might be different, but they all reflected the same objective fact, so it was possible to calculate the conversion rate according to any reagent. The conversion rate referred to the percentage or fraction of a certain reagent that was converted. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Reaction Rate Formula
1. For a chemical reaction, the reaction rate was calculated as: <<v>=<cC>(g)>+<dD>(g)>(v =<Delta c>/<Delta t>)(<v>: average rate,<<Delta c>>: concentration change,<<Delta t>>: time), in units of </(L·s)>. 2. For elementary reactions, the expression of the mass action law can be used as the reaction rate equation, the reaction rate equation, r = k(A)^a(B)^b, where k is the specific reaction constant (a quantity independent of concentration). 3. For the reaction,<aA(g)+bB(g)=cC(g)>, the reaction rate <v_positive = k_positive c^a(A)·c^b(B)>,<v_inverse = k_inverse c^c(C)>, when the reaction reaches equilibrium,<v_positive = v_inverse>, that is,<k_positive c^a(A)·c^b(B)=k_inverse c^c(C)>. 4. When the same reaction was expressed by different substances, the values might be different, but the meaning was the same. The reaction rates expressed by different substances had the relationship of [v(A): v(B): v(C): v(D)=m: n: c: d](the ratio of the rates was equal to the ratio of the measurement factors of the corresponding substances). <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The relationship between reaction rate constant and reaction concentration
The reaction rate constant was independent of the reaction concentration. The reaction rate equation is generally expressed as r = k(A)^a(B)^b, where k is the reaction rate constant, which represents the chemical reaction rate at a unit concentration. It is mainly affected by factors such as temperature, catalyst, and solid surface properties, but not by the concentration of the reagent. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The value of the reaction rate of the reagent
The value of the rate of an alcoholic reaction is usually expressed by the increase in the concentration of the product in a unit of time (it can also be expressed by the decrease in the concentration of the substance in a unit of time, but it is generally not used because it is not easy to measure), that is, v = dt (the concentration of change/the corresponding time of the reaction). The unit of concentration is usually in the form of mole/liter, mole/liter, mole/milliliter, or mole/milliliter, and the unit of time is in the form of seconds or minutes. However, the rate of the fermentation reaction was affected by many factors, such as temperature, concentration of the reagent, concentration of the reagent, and so on. The value would vary greatly under different conditions, and there was no fixed specific value. In the optimal temperature range, when other conditions remained unchanged, the reaction rate increased with the increase of temperature, and the fastest reaction rate was reached when the optimal temperature was reached. Under the condition of sufficient substances, the higher the concentration of the catalyst, the faster the reaction rate. Within a certain range of the concentration of the substances, the reaction rate increased with the increase of the concentration of the catalyst, and the reaction rate reached the fastest and no longer changed when the concentration reached the optimal concentration. The reaction rate would be reduced by the initiator, and the reaction rate would be accelerated by the initiator. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
multistep reaction rate equation
For multi-step reactions (complex reactions), the reaction rate equation could not be simply written according to the total reaction equation. Complex reactions were composed of multiple elementary reactions (reactions that could be completed after a single collision). In the elementary reaction, there is a strict quantitative relationship between the reaction rate and the concentration of the reagent. It follows the law of mass action, that is, at a constant temperature, the rate of the elementary reaction is proportional to the product of the power of the concentration of the reagent. The power index is equal to the Stoichiometer number in the reaction equation. The general form of the rate equation is: (v = kc^{a}(A)c^{b}(B)(where k is the rate constant, c(A) and c(B) are the concentration of the reagents, and a and b are the measurements in the reaction equation). However, for multi-step reactions, the rate of the entire reaction was usually determined by the slowest elementary reaction step. For example, the reaction mechanism of a complex reaction was: a)<X + Y> Z>(fast reaction);b)<Z + W> Q>(slow reaction, speed determining step). Then the rate equation of this complex reaction mainly depended on the rate equation of speed determining step b, the reaction rate <x>(v = kc(Z)c(W)>. If the concentration of the intermediate product <Z>> could be expressed by the reagents <X>,<Y>>, then the reaction rate equation expressed by the original reagents could be obtained. In short, the multi-step reaction rate equation needed to be determined by analyzing the reaction mechanism, determining the rate-determining step, and then combining the characteristics of each elementary reaction step and the relationship between the concentration of the reagents and the intermediate products. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What are the problems with the positive reaction rate being greater than the reverse reaction rate?
The reason why the positive reaction rate was greater than the reverse reaction rate was as follows: 1. ** Concentration Effect ** - When the concentration of the reagent increased, according to the collision theory, the effective collision frequency between the molecules of the reagent increased, and the positive reaction rate instantly increased. At this time, the concentration of the product had not changed, and the reverse reaction rate did not change. Therefore, the positive reaction rate was greater than the reverse reaction rate, and the reaction went forward. For example, in the reaction A + B, if the concentration of A or B increases, the positive reaction rate will increase before the reverse reaction rate. - When the concentration of the product was reduced, the reverse reaction rate would decrease. However, the positive reaction rate would not change when the concentration of the reagent remained unchanged. This would also cause the positive reaction rate to be greater than the reverse reaction rate, causing the reaction to move forward. 2. ** Effect of temperature (targeted at the heat reaction)** - For example, when the temperature was raised, the positive and reverse reaction rates increased. However, since the positive reaction was a thermal reaction, according to Le Chatelier's principle, the increase in temperature was not conducive to the progress of the thermal reaction, so the increase in the reverse reaction rate was greater than the increase in the positive reaction rate. Then, for a reaction that was a positive reaction, when the temperature was raised, the increase in the positive reaction rate was greater than the increase in the reverse reaction rate. The positive reaction rate was greater than the reverse reaction rate, and the reaction was positive. 3. ** Pressure effect (for reactions where the gas volume changes before and after the reaction)** - For example, for the reaction, the total volume of the gas before the reaction (1 + 3 = 4) is greater than the total volume of the gas after the reaction (2). When the pressure increases, according to the ideal gas state equation,[pV = nRT]([p] is the pressure,[V] is the volume,[n] is the amount of matter,[R] is the constant,[T] is the temperature), the gas concentration increases, and the positive and reverse reaction rates increase. However, because the reaction moved in the direction of decreasing the volume of the gas, the increase in the positive reaction rate was greater than the increase in the reverse reaction rate. The positive reaction rate was greater than the reverse reaction rate, and the reaction proceeded in the positive direction. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to determine the positive and negative reaction rate of a chemical reaction
The positive or negative of the change in the temperature had no direct relationship with the reaction rate. ** I. Judgment of Positive and Negative EnChange ** 1. ** Based on the energy of the reagents and products ** - If the total energy of the reagent is higher than the total energy of the product, there will be energy release during the reaction, and the change in the heat is an exothermic reaction. For example, in a combustion reaction, when a flammable substance and oxygen react to form a product, the energy of the reaction is higher than the energy of the combustion product. The reaction releases heat, and the heat becomes negative. - When the total energy of the reagent is lower than the total energy of the product, the reaction needs to absorb energy to proceed. The change in the heat is an heat absorption reaction. For example, the reaction of water gas, carbon and water vapor reacted at high temperatures to form carbon dioxide and hydrogen. The reaction needed to absorb heat, and the heat would become positive. 2. ** From the perspective of chemical bonds ** - The essence of chemical reactions was the breaking of old chemical bonds and the formation of new chemical bonds. The breaking of chemical bonds absorbed energy, and the formation of chemical bonds released energy. If the energy absorbed by a bond breaking reaction is less than the energy released by the bond forming reaction, the reaction will be heat releasing and the change in the heat will occur. On the other hand, if the energy absorbed by the bond breaking reaction is greater than the energy released by the bond forming reaction, the reaction will be heat absorbing and the change in the heat will occur. For example, when hydrogen and oxygen react to form water, the energy absorbed by separating the chemical bonds in hydrogen and oxygen is less than the energy released by forming the hydrogen and oxygen bonds in water. Therefore, the reaction is an exothermic reaction, and the energetics become negative. ** 2. Judgment of reaction rate ** 1. ** Concentration of Reactants ** - Generally speaking, under the same conditions, the higher the concentration of the reagent, the more molecules of the reagent in the unit volume, the higher the probability of collision between molecules, and the faster the reaction rate. 2. ** Temperatures ** - When the temperature rises, the energy of the molecules increases, the speed of the molecules increases, and the frequency of effective collisions increases, thus accelerating the reaction rate. 3. ** Pressure (for reactions involving gases)** - When the pressure increased, the volume of the gas decreased, the concentration of the reagents increased, and the reaction rate increased. However, the effect of pressure on the reaction rate was essentially achieved by changing the concentration. 4. ** A catalyst ** - The catalyst could reduce the activation energy of the reaction, making it easier for the molecules to react, thus speeding up the reaction rate. There were also some kinds of catalyst that could slow down the reaction rate, but they were relatively rare. 5. ** Solid surface area (for reactions involving solid)** - The larger the surface area of the solid, the larger the area of contact with other reagents, and the faster the reaction rate. For example, when bulk and powdered solid react with other reagents, the reaction rate of the powdered solid is usually faster. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>