Sodium carbonate and hydrochloric acid reaction

Sodium carbonate, people generally call it "soda", note that it is "soda" rather than "baking soda", "baking soda" is sodium bicarbonate, which is often used to ferment steamed buns. Although these two things sound similar, their uses are very different. The reaction between sodium carbonate and hydrochloric acid is a key point in teaching, and it also has certain significance in actual production and life applications. The reaction between sodium carbonate and hydrochloric acid is described in detail below.

Sodium carbonate, commonly known as soda, pure alkali, washing alkali, chemical formula: Na2CO3, usually white powder, a strong electrolyte. Density is 2.532g/cm3, melting point is 851°C, easily soluble in water, with the general properties of salt. Sodium carbonate is a weak acid and strong alkali salt. Na2CO3 produced by chemical methods is purer than natural alkali, so people call it "pure alkali". Pure alkali is an important large-tonnage chemical raw material.

I remember that the chemical formula of sodium carbonate (pure alkali) is Na2CO3, commonly known as pure alkali, also known as soda, alkali ash, an important basic chemical raw material, and the main product of the pure alkali industry. It is usually a white powder, easily decomposed at high temperature, easily soluble in water, and the aqueous solution is alkaline. Pure alkali will deliquesce in humid air, slowly absorb carbon dioxide and water, and partially turn into sodium bicarbonate, so the packaging must be tight, otherwise it will absorb moisture and agglomerate. Sodium carbonate reacts with water to form three hydrates: Na2CO3·10H2O, Na2CO3·7H2O, and Na2CO3·H2O. Among them, Na2CO3·10H2O is the most stable, and the heat of dissolution in water is very small. It is mostly used in the photographic industry, and its trade name is carbon oxide. Na2CO3·10H2O is also called crystal alkali. In the past, crystal alkali was often used for household washing and wool washing, so it was also called "washing alkali."

The discussion on the experiment of the reaction of sodium carbonate and sodium bicarbonate with hydrochloric acid has always attracted the attention of teachers and is one of the indispensable teaching contents in both new and old textbooks. Based on an in-depth analysis of the direct purpose and indirect significance of this experiment, combined with the new high school chemistry curriculum, further discussions and analyses are conducted on issues such as reaction rate, reaction mechanism, reaction heat effect and identification methods in existing research.

An experiment on page 32 of the first volume of the People's Education Press full-time senior high school textbook (compulsory) "Chemistry": Add 3 mL of dilute hydrochloric acid to each of two test tubes, and put two small balloons filled with 0.3 g of Na2CO3 or NaHCO3 powder on the mouth of the two test tubes. Pour the Na2CO3 and NaHCO3 in the balloon into the test tube at the same time and observe the reaction phenomenon. "Chemical Education" and "Chemical Teaching" have also published relevant research papers many times to improve this experiment. It can be seen that this experiment is one of the focus issues in high school chemistry teaching.