Sodium bicarbonate, with the molecular formula NaHCO æ, is an inorganic compound. It is a white powder or fine crystal, odorless, salty, easily soluble in water, slightly soluble in ethanol (some say insoluble), and the aqueous solution is slightly alkaline. It is prone to decomposition when heated and slowly decomposes in humid air, producing carbon dioxide. It begins to decompose at around 50 ℃ and is completely decomposed when heated to 270 ℃. When exposed to acid, it strongly decomposes and produces carbon dioxide. Sodium bicarbonate is widely used in industries such as chemical, pharmaceutical, food, light industry, textile, and people's daily lives, playing an important role in the national economy
chemical property
Acidity and alkalinity
The aqueous solution of sodium bicarbonate exhibits weak alkalinity due to hydrolysis:
HCO3-+H2O ⇌ H2CO3+OH -. The pH value of a 0.8% aqueous solution is 8.3 .
React with acid
Sodium bicarbonate can react with acids, such as with hydrochloric acid:
NaHCO3+HCl=NaCl+CO2 ↑+H2O .
React with alkali
Sodium bicarbonate can react with bases, such as sodium bicarbonate reacting with sodium hydroxide: NaHCO3+NaOH=Na2CO3+H2O; When reacting with calcium hydroxide, if there is sufficient sodium bicarbonate, there are:
2NaHCO3+Ca (OH) 2=CaCO3 ↓+Na2CO3+2H2O;
If there is a small amount of sodium bicarbonate, there is:
NaHCO3+Ca (OH) 2=CaCO3 ↓+NaOH+H2O .
React with salt
1. Sodium bicarbonate can undergo double hydrolysis with aluminum chloride and aluminum chlorate, producing aluminum hydroxide, sodium salt, and carbon dioxide. The chemical equations are:
3NaHCO3+AlCl3=Al (OH) 3 ↓+3NaCl+3CO2 ↑;
3NaHCO3+Al (ClO3) 3=Al (OH) 3 ↓+3NaClO3+3CO2 ↑ .
2. Sodium bicarbonate can undergo double decomposition reactions with certain metal salt solutions, such as
2HCO3-+Mg2+=CO2 ↑+MgCO3 ↓+H2O .
Thermal decomposition
Sodium bicarbonate has stable properties at room temperature and is easily decomposed when heated. It begins to decompose at around 50 ℃ and completely loses carbon dioxide at 270 ℃. It remains unchanged in dry air and slowly decomposes in humid air.