When doing questions, I always don t know the factors that affect the rate of chemical reactions

For chemical reactions with gas participation, when other conditions remain unchanged (except volume), the pressure increases, that is, the volume decreases, the concentration of reactants increases, the number of activated molecules per unit volume increases, the number of effective collisions per unit time increases, and the reaction rate accelerates; Otherwise, it decreases. If the volume is constant, the rate of the pressurized reaction (adding gases that do not participate in this chemical reaction) will not change.

Because the concentration does not change, the number of activated molecules per unit volume does not change. However, when the volume remains the same, the reactants are added, which is also pressurized, and the concentration of reactants is increased, and the rate will also increase. If the volume is variable, the constant pressure (adding gases that do not participate in this chemical reaction) reduces the reaction rate.

Because the volume increases, the amount of reactant substances does not change, the concentration of reactants decreases, and the number of activated molecules per unit volume decreases.

Temperature conditions As long as the temperature is raised, the reactant molecules gain energy, so that some of the original low energy molecules become activated molecules, which increases the percentage of activated molecules, so that the number of effective collisions increases, so the reaction rate increases (the main reason). Of course, as the temperature increases, the rate of molecular motion accelerates, and the reaction will increase as the number of molecular collisions of reactants per unit time increases

Catalyst The use of positive catalysts can reduce the energy required for the reaction, so that more reactant molecules become activated molecules, greatly increasing the percentage of reactant molecules per unit volume, thereby increasing the reactant rate thousands of times. Negative catalysts are the opposite. Catalysts can only change the rate of chemical reactions, but not the equilibrium of chemical reactions.

Conditional concentration When other conditions are the same, increasing the concentration of reactants increases the number of activated molecules per unit volume, thereby increasing the effective collision and the reaction rate, but the percentage of activated molecules remains unchanged.

Other factors Increasing the surface area of a certain amount of solid (such as crushing) can increase the reaction rate, and light can generally increase the rate of some reactions; In addition, ultrasound, electromagnetic waves, solvents, etc., also have an effect on the reaction rate.

Factors include: temperature, catalyst, contact area of reactants, etc

The rate of chemical reaction is made up of the following components: v

Forward and inverse: The rate of the chemical reaction indicates whether the rate of the positive reaction or the rate of the reverse reaction is inverted.

Species of substances: For different substances, the reaction rate may have different values, so it is necessary to mark the species of the substance to distinguish different reaction rates, for example, for N2+3H2=(reversible)=2NH3, V(N2) and V(NH3) represent the reaction rate expressed by nitrogen and the reaction rate expressed by ammonia, respectively.

Numerical value: The most basic component of the reaction rate, through which the speed of the reaction can be compared.

Units: The commonly used units are mol (l·s) and mol (l·min), and we must carefully model and distinguish the units when doing the questions, especially the problem of judging the reaction rate of the chain must unify the units and then compare the numerical size, which is converted to 1mol (l·s) = 60mol (l·min).

(1) The concentration of pure liquids and solids is regarded as constant, and the change in their amount does not affect the rate of chemical reaction. However, the size of the particles causes the size of the contact area to change, so the reaction rate is affected.

2) Solid and liquid substances, since the pressure changes have little effect on their volume, so the effect of pressure on their concentration can be regarded as constant, and the pressure has no effect on the rate of chemical reactions without the participation of gases.

3) The increase in temperature increases whether it is an endothermic reaction or an exothermic reaction, and whether it is a positive reaction rate or a reverse reaction rate.

4) For chemical reactions with the participation of gases, there are the following cases:

At constant temperature: compressing the volume of the reaction system leads to an increase in the induced pressure, which in turn leads to an increase in the concentration of reactants, which in turn leads to an increase in the reaction rate.

At constant temperature, for constant volume closed containers:

a.The filling of gas reactants leads to an increase in the concentration of gas reactants (as well as an increase in pressure), which leads to an increase in the reaction rate.

b.The addition of "inert" gas causes an increase in the total pressure of the gas, but the concentration of the gas reactants does not change, so that the reaction rate does not change.

At constant temperature and pressure: the filling of "inert" gas causes the volume of the reaction system to increase, which in turn causes the concentration of gas reactants to decrease, which leads to a decrease in the reaction rate.

5) When other things being equal, the chemical reaction rate is accelerated by using a catalyst.

6) In addition, light waves, electromagnetic waves, ultrasonics, solvents, etc. can also affect the rate of chemical reactions.

In general, the rate of chemical reaction is related to the following factors:

1.Concentration The higher the concentration, the faster the reaction rate;

2.Contact area The larger the contact area, the faster the reaction rate;

3.Catalyst In general, catalysts can greatly speed up the reaction rate;

4.Temperature In general, the higher the temperature, the more intense the molecular movement and the faster the reaction rate;

5.Pressure A reaction in which gas is involved or generated and the number of molecules changes before and after the reaction, usually the change in pressure has a great impact on the reaction rate.

The factors that affect the rate of chemical reactions are:

1. Reaction temperature;

2. The concentration of liquid drugs;

3. The contact area between solid drugs and liquid drugs; (granular or powdery) 4. Pressure;

The answer I worked out was d

The conversion rate of the specific process: a is, so the reactive formula can be listed:

1/2a + n/2b = m/2c

Because of the gas equation:

PV Nrt, when v, r, and t are constants, the pressure P is only related to the number of gas molecules n, and is proportional.

Total number of molecules before reaction:

1 n (because there is no reaction and no c generation, m 0).

Total number of molecules after reaction:

1/2 + n/2 +m/2

Ratio of the number of molecules before and after the reaction:

1 2 + n 2 + m 2) (1 + n) = 4 3 simplified:

5 + 5n = 3m

Only in the d option, n=2, m=5, conforms to the simplified equation, so the answer is d

d because a(g) + nb(g) = mc(g).

Start the 1 n 0 process.

The remainder is because (1+n) (

The solution is m (n+1)=5 3

So m n = 5 2

It can be seen from the option that it is d

1. The higher the temperature, the faster the reaction rate;

2. The catalyst accelerates the reaction rate;

3. The larger the contact area of the reactants, the faster the reaction rate.

Hello landlord: 1. Other conditions are certain, [the higher the temperature], the greater the molecular energy, and the faster the reaction rate.

2. For H2O2 and Mno2 as positive catalysts, [with positive catalysts] can accelerate the reaction rate (negative catalysts.

slows down the reaction rate).

3. The contact area of zinc powder with HCl is larger than that of zinc particles, so the reaction opportunity increases, resulting in the acceleration of the reaction rate.

The contact area with the reactant increases

I'm glad to answer for you, [] is the focus, and the rest is to strengthen memory.