Chemical carbon dioxide is an acidic gas, why can t you make the litmus solution red

co2+h2o-->h2co3

h2co3-->h+

hco3-hco3---h+co3

Because there is an ionization equilibrium constant in the ionization of 2,3 in the aqueous solution, you can check the table, you can calculate the total ionized hydrogen ions in the two steps of ionization, and because the litmus solution has a certain indication range, it needs a certain concentration of H+ to change its color, and in the above reaction, the ionized H+ does not have enough concentration, so it fails to make the indicator produce obvious color changes, so although carbon dioxide is an acidic gas, its aqueous solution is extremely acidic, so it cannot make the litmus solution red.

The principle that the indicator can change color is that the substances it contains react with H ions to form colored substances, because the concentration of H ions is low, and the substances generated are less, so it seems that there is no change in color.

It must be an acid that can make the litmus solution red, carbon dioxide is just an acidic gas, it is not an acid yet, it can only turn red after dissolving in water to produce carbonic acid.

Carbon dioxide melt produces a small amount of carbonic acid Carbonic acid is a weak acid.

If it is only soluble in water, there will be no color change, so it is not the reason for the water tolerance, and naturally it cannot be proved that it is carbonic acid that makes the litmus change color, nor can it prove that carbon dioxide is acidic.

Carbon dioxide dissolves in water to form carbonic acid and is highly volatile, and it becomes carbon dioxide and water again as soon as carbonic acid is formed.

Only when it is dissolved in water to form carbonic acid, it can turn red.

Purple litmus. The test solution turns red because the purple litmus regains its purple color after CO2 H2O H2CO3 is heated, and the reason is: H2CO3 (heated) CO2 H2O is added to activated carbon.

The solution gradually becomes colorless and transparent due to the adsorption of litmus molecules by activated carbon.

Problem solving ideas: according to the reaction of carbon dioxide and water to form carbonic acid, carbonate leakage is acidic, so that the purple litmus test solution turns red for analysis;

Carbon dioxide is passed into the purple litmus test solution, and the carbon dioxide is combined with water to form carbonic acid, which is acidic, making the purple litmus juice turn red before the test.

So choose d Comments:

Topics for this question: Chemical properties of carbon dioxide

Test Center Comments: This question examines the chemical properties of carbon dioxide and the discoloration of the indicator, and the acid makes the litmus red, and the litmus turns red

The chemical reaction equation of carbon dioxide and water reaction is: CO2+H2O=H2CO3; Acid can make the purple litmus solution red, purple litmus will change color when it meets acid or alkali, red when it is acid, and blue when it is alkaline, so carbon dioxide gas can make purple litmus solution red

So the answer is:

Correct Carbon dioxide gas can turn purple litmus solution red, because CO2 reacts with water to form acid, carbonic acid, and carbonic acid can make purple litmus red.

co2 + h2o==h2co3

After carbon dioxide is introduced into the old litmus test solution, and then the solution is heated, the phenomenon that occurs is: () starvation.

a.Turn red.

b.First it becomes rotten and envy red and then purple (correct answer).

c.It turns red first and then colorless.

d.It turns blue first and then purple.

Carbon dioxide is then introduced into the purple litmus solution, and the phenomenon is: the purple litmus solution turns red, because the carbon dioxide is combined with water to form carbonic acid, and the literal expression of the reaction is: carbon dioxide + water carbonic acid Then, heated, the observed phenomenon is that the red color fades and returns to purple, indicating that the carbonic acid is unstable, and the reaction text expression is:

Carbonic acid carbon dioxide + water

Therefore, the answer is: purple litmus solution turns red, carbon dioxide + water carbonic acid, red fades and returns to purple, carbon dioxide carbonate + water

In my opinion, carbon dioxide is able to turn litmus solution red.

Here's a look at the litmus discoloration mechanism.

Limus is a weak organic acid with a relative molecular weight of 3300, which changes its conjugate structure and changes color under the different actions of acid-base solutions. That is, in solution, as the acidity and alkalinity of the solution change, its molecular structure changes and presents different color changes:

In acidic solutions, molecules are the main form of their existence, giving the solution a red color; (The balance shifts to the left due to the increase in [h+]).

In the alkaline solution, the ionization equilibrium of litmus hydrolysis shifts to the right, and the acid ions produced by ionization are the main form of its existence, so the solution is blue; (The balance shifts right due to the increase in [oh-]).

In a neutral solution, molecules and acid ions coexist, resulting in a purple color. （[hz]=[z-]）

CO2 is an acidic oxide that reacts with water to form carbonate H2CO3, which can make the "purple" litmus "test solution" red.

CO2 cannot turn "dry" purple litmus "test strips" red (because there is no water and no carbonic acid can be generated).

CO2 is introduced into the "purple" litmus "test solution", which turns red (note to distinguish the "purple", "test strip", and "test solution" above).