How do purple litmus solutions react when they encounter acidic substances and turn blue when they e

Substances that can indicate the acidity and alkalinity of the solution through color changes, such as litmus, phenolphthalein, methyl orange, etc., are called acid-base indicators. Acid-base indicators are generally weak organic acids. Litmus is taken as an example to illustrate the principle of color change of the indicator.

The ionization equilibrium of litmus is expressed as follows: Hin = in- +H+

The molecular form of Hin is red, while the acid ion is in- blue. When the concentration of H+ in the system is large, the equilibrium shifts to the left, and when it is mostly in the form of molecules, it appears red. When the concentration of OH- in the system is large, the equilibrium shifts to the right, and when the ionic form is the majority, it shows blue.

No new matter is generated. It is a matter of ionization equilibrium. No deterioration.

For details, see page 63 of the sophomore chemistry textbook.

CO2 + H2O = H2CO3 H2CO3 is an acidic substance, so the purple litmus test solution turns red after reacting with it. I had just studied chemistry and didn't know much.

Different complexes are formed.

It is an acidic solution that can make the purple litmus solution red, an alkaline solution that can make the purple litmus solution blue, and a neutral solution that can not make the purple litmus change color, and it is still purple, so fill in: acidic, alkaline, purple

The solution of acid or alkali can change the color of the purple litmus solution or phenolphthalein solution, but it is not necessarily the acid or alkali solution that can change the color of the purple litmus solution or phenolphthalein solution, but it may also be an acidic salt solution or an alkaline salt solution, such as sodium bisulfate (NaHSO4) solution, which can ionize H+ and make the litmus solution red.

For example, sodium bicarbonate (NaHCO3) solution can make purple litmus solution blue, but sodium carbonate is not a base, but a salt.

Not necessarily.

The acidic solution can turn the purple litmus solution red. However, acidic solutions are not necessarily acids, but may be salts, such as aluminum sulfate, ammonium nitrate, etc.

litmus solution

It turns red when it is acid, and blue when it is alkaline.

It should be possible to conclude then.

The solution that can make purple litmus reddening must be an acidic solution.

There is an ionization equilibrium in the litmus solution, and the equilibrium moves in the direction of molecule (red) when it is acid, and it moves in the direction of ionization (blue) when it is alkaline, so it turns red when it is acid, and blue when it is alkaline.

Litmus is an organic acid extracted from lichen plants with a complex composition. In a very dilute litmus solution, there is an equal amount of ions that make the solution blue and molecules that make the solution red, and the mixture of red and blue gives the litmus solution a purple color. In acidic solutions, it is mainly found in the form of red molecules; In alkaline solutions, it is mainly present in the ionic form of blue.

The acid-base indicator has the following equilibrium relationship in solution:

In different acidic and alkaline solutions, litmus exists in different forms. The color is also different.

Litmus is a commonly used indicator with a range of discoloration that is between. The fact that litmus acts as an indicator is due to the presence of litmus (C7H7O4N) in litmus. The principle is that litmus is also a weak acid, and there is a balance in aqueous solution as follows:

hz represents litmus molecule in a neutral solution: [hz]=[z-] in an acidic solution: due to the increase in [h+], the equilibrium shifts to the left, and the solution is red.

In alkaline solution: due to the increase of [OH-], the equilibrium shifts to the right, and the solution appears blue.

Purple litmus turns red when exposed to an acidic solution.

What makes the purple litmus solution reddened is the hydrogen ion H+.

Acids are compounds that dissociate the only cationic hydrogen ion in solution. Such as: HCl, H2SO4, HNO3, can decompose the only cation hydrogen ions. There are two most important keywords here: one is hydrogen ion, and the other is the only cation.

That is to say, if the compound is in solution, it can dissociate hydrogen ions, and at the same time can dissociate other cations, then the compound is not an acid, but is called an acidic solution. For example, NaHCO3 solution can dissociate hydrogen ions, but at the same time, it can also dissociate cation sodium ions, so NaHCO3 solution is an acidic solution, not an acid solution.

And because the acidic solution can also dissociate hydrogen ions, hydrogen ions can make the purple litmus solution red. Therefore, purple litmus will not only turn red when exposed to acid, but also when exposed to acidic solutions. Of course, an acid solution is naturally an acidic solution.

What color does litmus turn when it encounters acid, and you will understand it in a minute.

The purple litmus test solution turns red when it is acid, and it turns blue when it is alkaline.

Phenolphthalein is originally colorless, does not change color when encountering acid, and turns red when encountering alkali.

Here should be for the color to look more obvious, phenolphthalein does not change color when it encounters acid, can not test the acid, when it encounters alkali red, the phenomenon is obvious, purple litmus test solution turns blue when alkali, it is originally purple, and the process of alkali turning blue is not obvious. Blue and purple are about the same. The phenomenon of purple litmus solution turning red when it encounters acid is obvious, so purple litmus solution is usually used to test acid.

The test base is usually with phenolphthalein test solution.

The litmus discoloration range is pH

In the acid solution, the H+ concentration is OH-concentration, so pH 7, but the solution of pH 7 is not necessarily an acid solution, some salts are dissolved in water, making the solution acidic, it should be said that "the solution that can make the purple litmus solution red must be an acidic solution". "A solution that does not discolor the phenolphthalein solution may be an acidic solution, a neutral solution, or a weakly alkaline solution.

It may also be a neutral solution or a weakly alkaline solution".

False, must be soluble acids and bases, such as Cu(OH)2 insoluble in water and will not discolor phenolphthalein and litmus.

This statement is false, it should be said: not necessarily!

For example, sodium hydroxide is soluble in water, and the solution can make the phenolphthalein test solution appear red, because sodium hydroxide is soluble in water and can ionize oh-root ions. Alkalis that are insoluble in water cannot discolor phenolphthalein, such as:

Copper hydroxide cannot discolor phenolphthalein because it is insoluble in water and cannot ionize oh-root ions, so it does not have such properties, so it is soluble alkali that can discolor the indicator.

It is an alkaline solution, but not necessarily an alkaline solution, such as sodium carbonate solution, which can make purple litmus solution blue or colorless phenolphthalein red, sodium carbonate is salt!