Junior Chemistry Purple Stone Core Test Solution and What Reactions Will Change Color 5

Litmus: When less than red.

Purple. Greater than blue.

Phenolphthalein: less than colorless.

Pink. More than 10 red.

Junior high school chemistry only requires me to remember that litmus turns red when it is acid, and it turns blue when it is alkaline.

This is useful in concept judgment questions, big inference questions, and ion coexistence questions.

ps;Concentrated sulfuric acid drops onto the litmus paper and turns black (dehydrated).

Hydrogen peroxide drops onto litmus paper and turns white (bleaching).

Note that it is a test strip.

More, acidic solutions (HCI, H2SO4...).It is red, alkaline solution (NaOH, Ca(OH)2....blue, and neutral violet (NaCl) (solution must be added to it).

Purple litmus is red when it is acid, and blue when it is alkaline.

Used to help determine the acidity or alkalinity of the liquid (but the exact pH value cannot be known) The liquid is dipped in a clean glass rod and dropped into the purple litmus solution. 1.If the test solution is red, it means that the liquid is acidic; 2.

If the test solution is blue, it means that the liquid is alkaline; 3.If it is purple, it is neutral. 4.

It can distinguish H2SO4, NaCl, Ca(OH)2 at one time Purple litmus test solution is one of the acid-base indicators for junior high school chemistry professors.

It is purple litmus, purple litmus and acidic solution are red and alkali are blue and blue.

The premise is that the substance to be tested must be soluble.

When exposed to acidic solutions (note that they are acidic solutions such as salts NH4NO3, not just acidic solutions) turn red.

In case of alkaline solution (ditto, such as salt Na2CO3) turns blue.

It does not change color in case of neutral objects.

Litmus turns red when exposed to acid and blue when exposed to alkali.

I have a mantra.

Phenolphthalein does not change when it encounters acid, and it becomes red and bright when it encounters alkali.

Litmus and litmus are endlessly varied, turning blue when exposed to alkali and red when exposed to acid.

Acidic and alkaline solutions.

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

Just study hard and run here to find the answer?

Both litmus and phenolphthalein are acid-base indicators that can be used to test whether the solution is acidic? Or is it an alkaline solution?

The litmus solution was originally purple, but it turned red when it encountered an acidic solution, and it turned blue when it encountered an alkaline solution, and it did not change color when it encountered a neutral solution, and it was still the original purple.

The phenolphthalein solution turns red when it encounters an alkaline solution, and it does not change color when it encounters an acidic or neutral solution, and it is still colorless.

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.

Chemical changes. Both litmus and phenolphthalein are acid-base indicators, and they are a weak organic acid. In solution, as the acidity and alkalinity of the solution change, the molecular structure of the indicator changes and shows different colors.

Litmus (denoted by HL) can be ionized in aqueous solution as follows: HL red H+ L-blue.

In acidic solutions, red molecules are the main form of existence, and the solution appears red; In alkaline solutions, the ionization equilibrium shifts to the right, and blue ions are the main form of existence, and the solution appears blue; In a neutral solution, red molecules and blue acid ions exist at the same time, so the solution appears purple.

Litmus is soluble in water, insoluble in alcohol, and the discoloration range is pH

Purple. Description:

1. If the test solution is red, it means that the liquid is acidic;

2. If the test difference macro liquid is blue, it means that the liquid is alkaline;

3. If it is purple (that is, the solution does not change color), it is neutral.

1. If the test solution is red, it means that the liquid is acidic;

2. If the test solution is blue, it means that the liquid is alkaline;

3. If it is purple (that is, the solution does not change color), it is neutral.

Litmus is a commonly used acid-base indicator with a discoloration range between pH = and color; It 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; 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.

Phenolphthalein. Chemical name: 3,3-bis(4-hydroxyphenyl)-1(3H)-isobenzofuranon.

Molecular formula: C20H14O4

Molecular weight: phenolphthalein is a weak organic acid, which has a colorless lactone structure in a solution at pH and a red quinone structure at pH. The quinone or quinone type of phenolphthalein is very unstable in alkaline media, and it will slowly be converted into a colorless carboxylate form; When encountering a more concentrated lye, it will immediately transform into a colorless carboxylate formula.

When a small amount of sodium hydroxide is encountered, it becomes 3,3-bis(4-benzoquinone)-1(3h)-isobenzofuranon, which is red; (Due to the difference in the absorption spectra of quinone and phenol, because the electron cloud of quinone is obviously no longer tire-shaped, but a carbonyl group with a considerable density of two electron clouds at both ends of the Western envelope structure).

Sodium hydroxide was overdosed to generate 3,3-bis(4-phenoxy)-1(3H)-isobenzofuranone disodium salt.

Litmus blue-purple powder. It is a blue pigment extracted from plants, which can be partially dissolved in water and appear blue. 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 the following equilibrium in aqueous solution: Hz represents litmus molecules.

In neutral solution: [Hz]=[z-].

In acidic solutions: Since [H+] is larger, 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.

Preparation of litmus solution] (1) Dissolve with hot alcohol to remove impurities and pour the alcohol away. (2) Add water to dissolve litmus, stir, stand and filter. (3) The filtrate is diluted to 1% to obtain litmus test solution.

Plagiarism is strictly prohibited!