Bases are those chemical species which can donate electrons, accept protons or can release hydroxide ions in aqueous solution.
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NaOH, Ca(OH)2, Na2CO3, NH3, LiOH, KOH, CsOH, Ba(OH)2, RbOH, NaNH2, NaH, SiO2, Al2O3, MgO, CaO, LiCO3 on silica, KNH2 on alumina, BaO, BeO, KCN etc.
We can see many examples of bases in everyday life as well. Many substances or chemicals which we use in our daily life are actually bases such as drain cleaner, detergent, lubricating grease, baking soda or baking powder, soaps, toothpaste, mouth wash, chewing gum, hair dye, pesticides etc.
General properties of bases are listed below –
Bases are slippery when dissolved in aqueous medium.
They taste bitter.
Aqueous solution of bases changes the color of red litmus paper into blue.
Bases give hydroxide ions on dissociation in water.
Alkali are those bases which can dissolve in water.
The pH level of bases ranges between 8-14.
Bases can react with acids and form salt and water.
Aqueous solution of bases can conduct electricity.
Bases can react with indicators such as litmus paper, phenolphthalein pink, bromothymol blue and methyl orange etc.
Bases can be classified on the basis of three factors acidity, concentration and degree of ionization.
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Bases also show acidity which depends on the number of hydroxyl ions it contains. Bases can be divided into three types based on acidity –
Mono Acidic Base – Base that contains only one hydroxyl ion and combines with one hydrogen ion is called a mono acidic base. For example, NaOH, KOH etc. are mono acidic bases.
Diacidic Base – Base that contains two hydroxyl ions and combines with two hydrogen ions is called di acidic base. For example, Ca(OH)2, Mg(OH)2 etc. are di acidic bases.
Triacidic Base – Base that contains three hydroxyl ions and combines with three hydrogen ions is called triacidic base. For example, Al(OH)3, Fe(OH)2 etc. are triacidic bases.
Bases can be classified in two types based on their concentration in their aqueous solution –
Concentrated Base – In these types of bases concentration of base is higher in the solution. For example, concentrated NaOH solution etc.
Diluted Base – In these types of bases concentration of base is relatively lower in their aqueous solution. For example, Dilute NaOH, dilute KOH etc.
Bases can be classified on the bases of their degree of ionization in the solution. It is also known as strength of base. It depends on the number of hydroxyl ions it produces when dissolved in water. Bases are of two types based their degree of ionization –
Strong Base – A base that dissociates completely or up to a high extent in water is called a strong base. For example, NaOH, KOH etc.
Weak Base – A base which doesn’t dissolve completely or dissociates up to very low extent is called a weak base. For example, NH4OH etc.
Bases are used in various fields. Few uses of bases are listed below –
Bases are used in manufacturing of soaps, toothpastes, paper, rayon etc.
It is largely used in the baking industry.
It is used in bleaching powder and used in cleaning purposes.
It is used in cleaning of sulfur dioxide.
It is used in whitewash.
It is used in the detergent manufacturing industry.
NH4OH is used to remove grease stains from clothes.
Chalk and oven cleaners are produced by bases.