Soda
The chemical composition of soda is sodium carbonate. Sodium carbonate (Na2CO3) is also called soda or soda powder.
The sodium carbonate hydrate with crystalline water is called sodium carbonate hydrate. There are three kinds of sodium carbonate hydrate: sodium carbonate hydrate (Na2CO3 H2O), sodium carbonate heptahydrate (Na2CO3 7H2O) and sodium carbonate decahydrate (Na2CO3 10H2O).
Anhydrous sodium carbonate is white powder, soluble in water and alkaline in aqueous solution. It has a strong hygroscopicity and can absorb water in the air and form hard blocks. Sodium carbonate decahydrate is a colorless crystal. When placed in air at room temperature, it will lose crystalline water and become sodium carbonate monohydrate. Whether sodium carbonate decahydrate or sodium carbonate monohydrate, heating will turn into anhydrous sodium carbonate. Sodium carbonate is stable and does not decompose easily when heated.
Carbon dioxide can be released when acid is encountered:
Na2CO3+2HCl=2NaCl+H2O+CO2_, the reaction speed is slower than that of baking soda with acid.
It can react with CaCl2 solution:
Na2CO3+CaCl2=CaCO3+2NaCl
In chemical plants, people inject carbon dioxide into the water solution of soda to make baking soda:
Na2CO3+CO2+H2O=2NaHCO3.
Sodium carbonate is the most widely used of the three kinds of soda. As a basic chemical raw material, soda is widely used in medicine (medical treatment for gastric acid excess), paper making, metallurgy, glass, soap, textile, petroleum, dyestuff and other industries. In daily life, soda also has many uses, such as it can be used directly as a detergent, steamed bread when adding some soda, can neutralize the acidic substances produced in the fermentation process.
Sodium bicarbonate
Sodium bicarbonate (NaHCO 3), a common name for sodium bicarbonate, is a white fine crystal. Its solubility in water is less than that of sodium carbonate. Sodium bicarbonate is weak alkaline when it dissolves in water.
Sodium bicarbonate can react with acid:
NaHCO 3+HCl=NaCl+CO 2+H 2,the reaction is rapid.
Reaction with alkali, such as NaOH:
NaHCO 3+NaOH= Narammed CO 3+H 2
Reaction with calcium hydroxide: Sodium bicarbonate dosage should be small and excessive.
A few:
Ca(OH)2+NaHCO 3= CaCO 3_+NaOH+H_2
Overdose:
Ca(OH)2+2NaHCO 3= Narammed CO 3+CaCO 3+2H 2O
Sodium bicarbonate does not react with CaCl2 solution.
Sodium bicarbonate is unstable and the solid begins to decompose gradually at above 50 ~C: 2NaHCO 3=() Na2CO3+H_2+CO_2_
Double hydrolysis of Al3+ occurs:
Al3++3HCO 3-= Al(OH)3_+3CO 2_
Sodium bicarbonate is widely used. It can be directly used as raw material in pharmaceutical industry to treat hyperacidity. It can also be used in film making, tanning, mineral processing, smelting, metal heat treatment, as well as in the fiber and rubber industries. One of the most widely used loosening agents in food industry is used to produce biscuits, pastries, steamed bread, etc. It is a carbon dioxide generator in soda drinks. It can be compounded with alum as alkaline fermentation powder or with soda as civil lime. It can also be used as butter preservative. Fire fighting equipment is used for the production of acid and alkali fire extinguishing agents and foam extinguishing agents. Rubber industry uses it with alum, H blooming agent to play the role of uniform blooming for rubber, sponge production. Metallurgical industry is used as flux for ingot casting. Machinery industry is used as forming aids for casting steel (sand turning) sand moulds. Printing and dyeing industry is used as fixing agent, acid-base buffer and rear treatment agent for dyeing and finishing of fabrics. The addition of baking soda in dyeing can prevent the yarn from producing colored flowers. Pharmaceutical industry is used as raw material of acid-making agent.
Sodium thiosulfate
Soda is the common name of sodium thiosulfate (Na2S2O3. 5H2O), also known as "Haibo". Soda is a colorless and transparent crystal, with weak alkalinity, soluble in water, but not in alcohol.
Sodium thiosulfate is obtained by co-cooking sodium sulfite and sulphur in industrial use and refined by recrystallization.
Na2SO3+S+5H2O = Na2S2O3.5H2O
It loses crystalline water by weathering in dry air above 33 C. It is relatively stable in neutral and alkaline solutions and decomposes rapidly in acidic solutions.
Na2S2O3+2HCl=2NaCl+H2O+S_+SO2_
Sodium bicarbonate has strong complexing ability and can form complex with silver bromide. Reaction mode:
AgBr+2Na2S2O3=NaBr+Na3 [Ag(S2O3)2], according to this property, it can be used as fixing agent. During phase washing, excessive soda reacts with silver bromide in the non-photosensitive part of the film and converts into soluble Na3 [Ag (S2O 3) 2], removing AgBr and fixing the developing part.
Soda also has strong reducibility and can reduce chlorine and other substances. Na2S2O3+4Cl2+5H2O = H2SO4+2NaCl+6HCl, so it can be used as dechlorination agent for bleached cotton fabric. Similarly, iodine stains on fabrics can also be removed.
In addition, soda is also used for tanning leather, electroplating and extracting silver from ores.
