What is the pH of sodium bicarbonate and sodium carbonate after hydrolysis

Because a large amount of hydroxide will be produced during hydrolysis, sodium bicarbonate will also be ionized to produce hydrogen ions, and hydrogen ions and hydroxide will be neutralized together, so the alkalinity is weak, and the pH value will become low.

Sodium carbonate [497-19-8](Na2CO3), molecular weight. The purity of chemicals is mostly above (mass fraction), also known as soda ash, but the classification belongs to salt, not alkali. Also known as soda or soda ash in international **.

It is an important organic chemical raw material, mainly used in the production of flat glass, glass products and ceramic glaze. It is also widely used in household washing, acid neutralization, and food processing.

Sodium bicarbonate (Nahco), commonly known as baking soda. White fine crystals, less soluble in water than sodium carbonate. It is an industrial chemical with low toxicity.

Solids above 50 begin to gradually decompose to produce sodium carbonate, carbon dioxide and water, and completely decompose at 440. Sodium bicarbonate is an acid salt formed after neutralization of strong alkali and weak acid, which is weakly alkaline when dissolved in water. This property allows it to be used as a leavening agent in the food production process.

Sodium bicarbonate will remain sodium carbonate after action, and too much use will make the finished product have an alkaline taste.

Because they differ in their ionic composition.

Both carbonate and bicarbonate undergo hydrolysis, but.

One sodium carbonate molecule can ionize two sodium hydroxide molecules, while one sodium bicarbonate molecule can only ionize one sodium hydroxide molecule;

Compared with carbonate, bicarbonate will also be ionized, ionizing hydrogen ions, making it less alkaline;

It can be explained from the formation of matter. An alkaline sodium carbonate molecule is combined with an acidic carbonic acid molecule to form two basic sodium bicarbonate molecules. So one part sodium carbonate molecule is stronger than two parts sodium bicarbonate molecule.

So the pH of sodium carbonate is greater than that of sodium bicarbonate.

Sodium carbonate. The degree of hydrolysis is greater than sodium bicarbonate.

It is based on the concentration of the same substance.

The alkalinity of the next two is judged.

For strong bases and weak acids.

In the case of salt, hydrolysis is greater than ionization, indicating that the solution is alkaline.

The specifics can be explained by the degree of hydrolysis (primary hydrolysis and secondary water) and ionization.

1) For NaHCO3, bicarbonate.

Hydrolysis and ionization occur.

Hydrolysis equation: HCO3-+H2O=H2CO3+OH-, OH- will be released, making the solution alkaline;

The ionization equation: HCO3-=(CO3)2-+H+, H+ will be released, making the solution acidic;

However, since the hydrolysis of bicarbonate is greater than ionization, C(OH-)>C(H+), so the sodium bicarbonate solution is alkaline.

Note: Hydrolysis or ionization here generally refers to the hydrolysis or ionization of the corresponding weakly acidic acid. )

2) For Na2CO3, hydrolysis of carbonate occurs.

CO3)2-+H2O=HCO3-+OH-, which will release OH- and make the solution alkaline;

HCO3-+H2O==H2CO3+OH-, which also releases OH-, but the degree of secondary hydrolysis is much smaller than that of primary hydrolysis (negligible);

Of course, at this time, the bicarbonate obtained by first-stage hydrolysis will also be ionized in the field to obtain H+, but with the first hydrolysis reaction.

Mainly. Secondary hydrolysis and especially ionization of bicarbonate can be ignored. Therefore, the Na2CO3 solution is alkaline.

It can be seen from the above that the degree of hydrolysis of sodium carbonate and sodium bicarbonate can be reflected by their primary hydrolysis, and the amount and concentration of the hydrolyzed oh- substance can reflect the degree of hydrolysis, that is, the alkalinity of the two can be judged by the amount concentration of the same substance, because the alkalinity of sodium carbonate is much greater than that of sodium bicarbonate at the amount concentration of the same substance, so the degree of hydrolysis of sodium carbonate is greater than that of sodium bicarbonate.

The acid corresponding to sodium bicarbonate is carbonic acid, which is a weak acid and is a weak electrolyte. According to the hydrolysis definition of salt, the weak ions in the salt combine with hydrogen ions or hydroxide ions ionized by water to form a weak electrolyte. Clearly meets the definition and can be hydrolyzed.

Hydrolysis equation: NaHCO3 + H2O=NaOH + H2CO3 hydrolysis ion equation: HCO3- +H2O=OH- +H2CO3 The same is often examined as the hydrolysis of sodium carbonate.

Summary. The reason why the second step of hydrolysis is not considered when finding the pH of sodium carbonate is that because the hydrolysis reaction of sodium carbonate is very fast, in actual operation, sodium carbonate has been fully hydrolyzed, that is, its pH value is only affected by the one-step hydrolysis reaction.

Therefore, when finding the pH of sodium carbonate, the second step of hydrolysis is not considered.

The reason why the second step of hydrolysis is not considered when calculating the pH of sodium carbonate is that due to the rapid hydrolysis reaction of sodium carbonate, in practice, sodium carbonate has been hydrolyzed in its entirety, that is, the pH value of its parsley is only affected by the one-step hydrolysis reaction. Therefore, when seeking the pH of sodium sodium in carbonic acid, the second step of hydrolysis is not considered.

How to find the concentration of H ions electrolyzed by water in salt corresponding to weak acid and weak base.

The H+ concentration of water electrolysis in the salt corresponding to the weak acid and weak alkali can be obtained by the titration method. The specific steps are as follows:1

Add the sample to a certain amount of dilute sulfuric acid and add an appropriate amount of indicator; 2.Add an appropriate amount of standard socks to touch NaOH solution and stir well until the reaction is equilibrate; 3.Measure the pH value with a pH test strip or pH electrode; 4.

The H+ concentration is calculated from the pH value.

The pH of the salt corresponding to the weak base is 9, and what is the concentration of H ions ionized by water.

The H+ concentration can be calculated according to the pH value, and the following formula can be used: H+ concentration = 10 (-pH) Therefore, when pH = 9, H+ concentration = 10 (-9) =

Ionized water and electricity?

Yes. The pH of sodium acetate is 9, and the concentration of hydroxide ions ionized by water is 10 to the minus 9 power.

Sodium acetate has a pH of 9, which indicates that it is a strong acid with a high amount of H+ ions. When water ionizes, it produces H+ and OH- ions, but because the concentration of H+ ions is too large, the concentration of OH- ions is very low. Based on kw = [h+][oh-] 10 -14, it can be inferred that the front [h+] 10 -9, i.e., the hydroxide or root ion concentration of 10 ionized by water is minus ninth.