On the question of the rate of chemical reactions, the question of the rate of chemical reactions

Question 1 Hydrochloric acid contains hydrogen ions.

Sulfuric acid contains hydrogen ions.

Nitric acid contains hydrogen ions.

A option with a different concentration of hydrogen ions cannot be selected.

Question 2 Because of the excess of ZN powder, as long as the total amount of hydrogen ions is not changed, the total amount of hydrogen will not change option a, sodium sulfate solid water absorption will increase the concentration of sulfuric acid and accelerate the reaction, so it cannot be selected.

Option b: Adding water to reduce the concentration of sulfuric acid and slowing down the reaction is the correct option.

Option C adds a solution of potassium sulfate, which only increases the total amount of sulfate, while the concentration of hydrogen ions decreases, and the total amount remains the same, so C is also correct.

Let's be clear: the rate of chemical reaction is proportional to the ion concentration, which means that all other things being equal, the greater the ion concentration, the faster the reaction rate. Hydrochloric acid HCl only has H ions and H2SO4 sulfate has H ions, nitric acid also has only H ions, so B is right.

The second question, the first review of the question said that in order to slow down the rate of the reaction, but do not affect the total amount of hydrogen generated, the slowdown rate means that it can reduce the ion concentration, and does not affect the total amount of hydrogen, that is to say, the added substances do not reflect with h ions, a sodium sulfate solid can not slow down the rate b is to reduce the ion concentration c is a solution, there is water in the solution, which is equivalent to adding water, and potassium sulfate does not react with h ions.

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1.The reaction with sodium hydroxide and calcium carbonate mainly depends on the concentration of hydrogen ions, hydrochloric acid and sulfuric acid are one is, of course, different. In option b, nitrate does not produce a slightly soluble precipitate like sulfate, which reduces the reaction rate, and the reaction rate is the same if the concentration of hydrogen ions is the same.

2.The function of water is to reduce the concentration of hydrogen ions, but the amount of hydrogen ions remains largely unchanged, so water can; The solvent of potassium sulfate solution is water, so it is a principle, and it is possible that high concentrations of sulfate will also have an effect on the reaction, but it does not need to be considered in the college entrance examination stage.

Option A of the first question, when the acid reacts with the base, it is not the acid-base concentration that is looked at, but the hydrogen ion and hydroxide concentration, and the concentration of bisulfate ions per liter is greater in moles, so the reaction rate is different.

In the second question A, because it is a solid sodium sulfate, when sodium sulfate is added, it will dissolve in water, so that the sulfuric acid becomes concentrated, and when the concentrated sulfuric acid reacts with zinc powder, sulfur dioxide gas will be generated, which will affect the total amount of hydrogen produced, but this is not the case in BC.

1. After the reversible reaction increases the concentration of reactants, when the equilibrium is re-reached, the concentration of the product also increases, so both V positive and V inverse will increase.

2, According to the ideal gas equation, the pressure in PV=NRT is actually the partial pressure of a particular gas. For example, air, one atmosphere. Then the oxygen pressure in it is actually only one atmosphere.

As mentioned above, the pressure is increased, and the volume and temperature of the container remain unchanged, because the overall pressure should be increased by filling the fixed container with inert (gas that does not participate in the reaction), but the partial pressure of the reaction gas does not change at all, so the concentration does not change. , so the rate does not change.

The conversion rate should be the amount of the reactant that has reacted to the total amount of the reactant. Therefore, when a reactant is added, the equilibrium moves in the direction of the positive reaction, and the amount of the reactant that has been reacted by the rest of the reactants increases, and the total amount of reactants does not change, so the conversion rate increases. The added reactants, that is, changing the reaction conditions, are obtained by the equilibrium movement principle (that is, the chemical equilibrium always moves in the direction of the change of weakening conditions), and the changed conditions can only weaken, not cancel, so the amount of reactants and the total amount of reactants increase at the same time, but the increase of the total amount of reactants is greater than the increase of the amount of reactants that have reacted, so the conversion rate decreases.

The core of Le Chatre's principle is that the conditions of change can only be weakened, not canceled, a bit like the change in the magnetic flux of a physical quantity.

The total amount has increased, and the conversion rate has of course decreased, which is equivalent to a larger denominator.

This should be seen in conjunction with the chemical equilibrium expression, and these contents are in the chemical reaction principles in the high school elective, so I won't say more.

The total amount is more, but the reaction is not synchronized with the increase, so the conversion rate is reduced.

The relative density of hydrogen is a mixture of nitrogen and hydrogen.

m-mixed = n2 28

h2 2 so n(n2): n(h2)=:3

Volume ratio of nitrogen to hydrogen entering the vessel: 1:3

n2 + 3h2 <*****> 2nh3

n up x 3x 0

n becomes y 3y 2y

n-flat x-y 3x-3y 2y

Ammonia accounts for 25%: 2y [(x-y)+(3x-3y)+2y]=25% y x=2 5

Nitrogen conversion rate: y x = 40%.

The ratio of the pressure before and after the reaction (x+3x) [(x-y)+(3x-3y)+2y]=

Density ratio before and after the reaction: density ratio = m mixing ratio.

So: (28x+3x*2) 4x: [x-y)*28+(3x-3y)*2+2y*17]=(34 4): 34=1:4

It can be seen that the average molar mass of the mixture is n2:h2=1:3 by the cross method, with nitrogen 1mol, ammonia 3mol, container volume 1L, n2+3h2====2NH3

Initial concentration 1 3 0 reaction concentration x 3x 2x equilibrium concentration 1-x 3-3x 2x because (2x) (1-x+3-3x+2x)=25%, x=

So (1) 1:3

2) (3) The volume of the container is constant, and the pressure ratio is equal to the quantity ratio of the total gaseous substance, that is, 4::4 (4) density = m v, and the mass and container volume are unchanged, so it is 1:1

The reason why chemical reactions are endothermic is because the energy required to break the chemical bond is greater than the energy released by the formation of the chemical bond;

And the chemical bond formed here is also the chemical bond that is broken by the reverse reaction;

So the key lies in the fact that the chemical bond energy of the two reactions breaking here is different;

That is, the energy required is different, one needs more energy, and the other needs less energy;

If you need a lot of energy, you raise the temperature for him, that is, increase the energy**, he will always not dislike it, but if he needs less energy, his demand for energy is not so great, and if he gives more, it will be wasted;

It can be understood in this way that the endothermic reaction has a large energy demand, and the exothermic reaction has a small energy demand and a large demand, so the change in heat is more obvious;

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The change in a concentration before and after the reaction is 1 mol l

The rate is mol lmin

The reaction rate is proportional to the coefficient, then.

v(a)：v(c)===2 ：n== ：

n==3 consumes a as mol

then n(b)== mol is generated

Option b can convert the rate of different substances into the same substance according to the coefficient ratio of the chemical equation, and then compare.

Convert all four options to the rate at which substance A is converted (note that the units should be uniform, all converted to mol (l min)).

a + 3b ⇔ 2c + 2d

a．v(a)=

b．v(b)＝

Because a and b are 1:3 reactions.

So the rate of a at this point is: v(a)= 3 = mol (l s) = =24 mol (l min).

c v(c)=

Because A and C are 1:2

So the rate of a at this point is: v(a)= 2 = mol (l min).

d v(d)=

Because a and d are 1:2

So the rate of a at this point is: v(a)= 2 = mol (l s) = * 60 = 3 mol (l min).

From this, it can be seen that option B has the highest rate, so choose B

I don't understand hi

A converts all these options to the speed of b, respectively.

So a fastest.

b Note that the unit is unified, and the reaction rate of the rest of the substances is calculated based on one substance.