Baking soda is sodium bicarbonate, also known as acid sodium carbonate. It is an acid salt with the chemical formula NaHCO3. White fine crystals, the solubility in water is less than sodium carbonate. The solid begins to decompose gradually to produce sodium carbonate, carbon dioxide and water above 50℃, and completely decomposes at 270℃. Sodium bicarbonate is an acid salt formed by the neutralization of a strong base and a weak acid, and it appears weakly alkaline when dissolved in water. This feature is often used as a leavening agent in the food production process. Sodium bicarbonate will leave sodium carbonate after its action. Too much use will make the finished product have an alkaline taste.
1. Physical properties
Sodium bicarbonate is pure white crystals of sodium bicarbonate, or fine crystals of opaque monoclinic system.
The proportion is 2.159. Odorless, salty, soluble in water, slightly soluble in ethanol.
Its aqueous solution is slightly alkaline due to hydrolysis and easily decomposes when heated. It decomposes rapidly above 65°C, and completely loses carbon dioxide at 270°C.
No change in dry air, and slowly decomposes in moist air.
Solubility: 7.8g/100mL, 18 °C; 16.0g/100mL, 60°C 16.0g/100mL.
2. Chemical properties
(1) React with HCl: NaHCO3(aq)+HCl(aq)——→NaCl+H2O(l)+CO2↑
(2) Reaction with NaOH: NaHCO3(aq)+NaOH(aq)——Na2CO3+H2O(l)
(3) Double hydrolysis with AlCl3: 3NaHCO3(aq)+AlCl3(aq)——→Al(OH)3(s)+3CO2(g)+3NaCl
(4) Double hydrolysis with Al2(SO4)3: Al2(SO4)3+6NaHCO3==3Na2SO4+2Al(OH)3↓+6CO2↑
(5) React with CaCl2: 2NaHCO3+CaCl2=Ca(HCO3)2+2NaCl
(6) React with calcium hydroxide:
Small amount: 2NaHCO3(aq)+Ca(OH)2(aq)——→Na2CO3+CaCO3(s)+2H2O(l)
(7) Thermal decomposition: 2NaHCO3(s)—△→Na2CO3(s)+H2O(g)+CO2↑(g)Tags: NaHCO3, soda