If a small amount of the following solids is added to dilute sulfuric acid, the pH value of the solu

Answer: AA: Magnesium oxide reacts with dilute sulfuric acid to form magnesium sulfate (strong acid and weak alkali salt) and water, and the solution is acidic after the reaction.

B: Potassium carbonate reacts with dilute sulfuric acid to form potassium sulfate (strong acid and strong alkali salt) and water, and the solution is neutral after the reaction.

C: Barium hydroxide reacts with dilute sulfuric acid to form barium sulfate (insoluble) and water, and the solution is neutral after the reaction.

D: Barium oxide reacts with dilute sulfuric acid to produce barium sulfate (insoluble) and water, and the solution is neutral after the reaction.

To sum up, only after the A reaction the solution continues to be acidic, and the pH changes the least, so the answer is A

In essence, the four substances can be reacted with hydrogen ions to form corresponding salts, which consume hydrogen ions in the solution and increase the pH of the solution. However, in this problem, the sulfuric acid and solid reaction are used, and the barium sulfate produced by D will wrap the barium oxide to prevent the reaction from proceeding, so the pH does not change much.

The solubility of barium hydroxide is much greater than that of barium oxide, which can be approximated as a liquid-phase reaction and can be carried out to the end.

This question mainly examines whether the reaction can be carried out to the end, rather than the hydrolysis of the product. In the presence of strong acids and bases, there is basically no need to consider the pH change due to hydrolysis.

A. MGO+H2SO4=MGSO4+H2O basic oxide reacts with strong acid.

B, K2CO3 + H2SO4 = K2SO4 + H2O + CO2 C, BA (OH) 2 + H2SO4 = BASO4 + 2H2OD, Bao + H2SO4 = BaSO4 + H2O In summary, B, strong acid and alkali salt and gas C, D precipitation and water. pH neutral.

A strong acid and weak alkali salt, (who is strong and who is sexual, this is the teacher's memory mantra of the occasion) is acidic, the pH does not change much, choose A

dBarium oxide reacts with dilute sulfuric acid to form BaSO4 covering the solid surface, preventing the reaction from proceeding, and it is basically not reacting, so the pH value of the solution does not change much.

It should be DB, C is alkaline, obviously not.

and D and H2SO4 form BaSO4 precipitate. A and H2SO4 generate MgSO4 and cannot be removed.

So I think D

a。The resulting magnesium sulfate is a strong acid and weak alkali salt, and the rest are neutral.

no enough information to answer:

1, A small amount of mean how much?the same weight or the same equivalent of each chemcial?

2, dilute sulphuric acid means dilute and how much dilute sulphuric acid?

3, stiring when adding in?

4, how much you wait to measure the ph after you added a small amount of solids?

If they are equivalent and wait until they react, then the answer is a

Physical method, add water, dilute the solution.

Chemical methods. 1, Add iron, consume sulfuric acid after the reaction, produce hydrogen and ferrous sulfate plus metal, produce hydrogen.

2. Add calcium carbonate to generate calcium sulfate and carbon dioxide, water, consume sulfuric acid and add weak acid to generate weak acid and salt.

3, Add sodium hydroxide to produce sodium sulfate, water, consume sulfuric acid and alkali to produce salt and water.

A physical method – adding water.

Three chemical methods – the addition of active metals, basic oxides, alkalis.

Physical Method: Add water.

Chemical method: add alkali, add weak acid, strong alkali salt, add .........I can't think of it.

Physical Add water.

Chemical: add alkali, add carbonate, add active metal.

The following solids are put into dilute sulfuric acid, and the acidity of dilute sulfuric acid will not be significantly weakened is barium chloride.

Potassium carbonate, sodium hydroxide and calcium oxide are all alkaline and will neutralize with sulfuric acid, reducing the concentration of hydrogen ions. Barium chloride reacts with sulfuric acid to form a barium sulfate precipitate, and at the same time produces hydrochloric acid, which is more acidic than sulfuric acid, so its acidity does not weaken.

First, pH = -LG (C(H+)) that is, pH = 1 itself refers to C(H+) = in solution, so it is.

In the second and a a, sulfate ions and barium ions are precipitated; The solution in b that turns the purple hail test solution red, the solution sail becomes acidic, so the bicarbonate ion is not good; C hydrogen ions, nitrate ions are nitric acid, which react with AI to release no or no, so it is wrong. then select D

3rd, 3fe2+

4h+no₃=3fe3+

no(g)2h o, the ion equation will also work, you can combine it yourself.

Fourth, copper ions and sulfur ions form Cus, which is extremely insoluble in water.

The concentration of hydrogen ions in the sulfuric acid solution of a pH=1 is, and the amount of substances containing hydrogen ions in the solution of 1L is not sock, and the number of H+ contained is , so A is wrong;

b The carbon-carbon bond in the benzene molecule is a unique bond, and there is no carbon-carbon double bond in the molecule, so b is wrong;

c is not a standard condition, and the molar volume of the gas under the standard condition cannot be used to calculate the amount of a substance mixed with CO2, so c is wrong;

Dt, the Ksp=4 10-8 of MgCO3, then the concentration of magnesium ions in the saturated MgCO3 solution at this temperature is: C(Mg2+)=

mol l = 2 10-4mol l, the amount of substances containing magnesium ions in 1 L saturated MGC3 solution is 2 10-4mol, and the number of mg2+ contained is 2 10-4

na, so d is correct;

Therefore, choose D

Option B; Because the concentrated sulfuric acid is diluted with water, the solute remains unchanged and the solvent increases, so the mass fraction of the solute in the solution becomes [small], that is, the option "does not match the reality" is b; Concentrated sulfuric acid is diluted with water, and the acidity is weakened, so the pH of the solution becomes larger, correct.

In the process of dilution of concentrated sulfuric acid with water, the following changes are inconsistent with the actual B, and the mass fraction of the solute in the solution becomes larger. The dilution process is when the solute mass becomes smaller.

Option B, but the solvent increases, but the solute does not change.

An increase in pH indicates a decrease in the concentration of hydrogen ions.

a Not reflected.

b reflected, but the concentration of hydrogen ions did not change, so the acidity did not change.

c The reaction consumes the hydrogen ions and the pH increases.

d Unresponsive.

Answer: c

It will react with dilute hydrochloric acid to form a salt solution, which will cause a large change in pH value, and the salt solution of d will not reflect hydrochloric acid, so the pH value will change the least extent.

The chemical equation of A: Na2CO3+2HCl=2NaCl+H2O+CO2 The chemical equation of B: CaO+2HCl=CaCl2+H2OC:

Ba(OH)2+2HCl=BACl2+2H2OD does not react.

Answer: DA: Sodium carbonate B: Calcium oxide C: Barium hydroxide These three substances all react with hydrochloric acid and consume H+, while D: Magnesium sulfate does not react with hydrochloric acid.

The answer is that all the substances in it can react with hydrochloric acid and change the pH value, and D does not participate in the reaction and exists in ionic form with minimal change in the pH value.

Obviously all are alkaline, d is neutral.