Examples of bases with its properties are as follows −
Bases have pH value more than 7.
Aqueous solution of basic compounds undergoes ionization and can conduct electricity.
On reacting base with acids can produce salts.
The concentrated base or strong base is known as Caustic.
If base added to alkaline solution it has bitter taste.
Base get identify easily due to the presence of OH- ions.
On applying red litmus paper to basic solution it changes the colour into blue.
On adding to acids compounds base can react vigorously.
On adding base to water it can conduct electricity.
It is a slippery substance in nature.
The basic compounds get classified on the basis of its concentration, acidity and ionization degree.
There are three types of bases as per its acidity −
Monoacidic base – The compounds has only one hydroxide ion (OH-) and able to react with only one hydrogen (H+) ion. Examples: NaOH, KOH, etc.
Di-acidic base – The compounds has two hydroxide (OH-) ions and able to react with two hydrogen (H+) ions. Examples: $\mathrm{Ca(OH)_2}$.
Tri-acidic base: The compounds has three hydroxide (OH-) ion and can reacts with three hydrogen (H+) ions. Examples: $\mathrm{Al(OH)_3}$.
Types of bases according to its concentration −
Dilute base: Low concentration of base in solution. Example: Dilute KOH, dilute $\mathrm{Ca(OH)_2}$, etc.
Concentrated base: High concentration of base in solution. Example: Concentrated NaOH, concentrated $\mathrm{Mg(OH)_2}$, etc.
Types of base on it ionization degree −
Strong Base: The base which gets completely ionized in water solution is called strong base. Example: NaOH.
Weak Base: The base which does not completely get ionized into water solution is called weak base. Example: $\mathrm{NH_4OH}$.
Base like NaOH (sodium hydroxide) is used in preparation of rayon, paper, soap, etc.
$\mathrm{Mg(OH)_2}$ (magnesium hydroxide) is used as an antacid.
$\mathrm{Ca(OH)_2}$ (calcium hydroxide) is used as a dry powder mixture for painting and decoration. It is also used in bleaching powder.
$\mathrm{NH_4OH}$ (ammonium hydroxide) is used in laboratories.
The examples of the various bases are listed below.
$\mathrm{Ba(OH)_2}$ is a strong base. It is a di-acidic base. It can ionize completely on adding to water and can form OH- ion in water.
$\mathrm{NH_4OH}$ is a weak base. It is a monoacidic base. It cannot completely ionize on adding to water and form very less OH- ions in water solution.
NaOH is a strong base. It is a monoacidic base. It get completely dissociate into water. It is also known as caustic soda.
$\mathrm{Al_2O_3}$ can act both as acid and base as it is an amphoteric oxide. It can react with strong acid and form salt. Thus it acts like a base.
$$\mathrm{Al_2O_3 + 6 HCl\:\rightarrow\:2 AlCl_3 + 3 H_2O}$$
CaO is a strong base. It comes under solid bases. It is a metallic oxide. On reacting CaO with water solution it forms a strong base. It is also known as quicklime.
Figure 1: Strong bases with aqueous solution
$\mathrm{Al(OH)_3}$ is an amphoteric substance and acts as an acid as well as base. It acts as a weak base. It can react with strong acids.
KOH is a strong base because it can dissociate totally in water solution. It is monoacidic base and also known as caustic potash.
Ammonia can act as a lewis base as it can donate its extra electrons to lewis acid and shows basic character.
$\mathrm{Fe(OH)_3}$ is tri-acidic base. It acts as weak base as it get dissociate incompletely on adding to water solution.
The $\mathrm{Sr(OH)_2}$ is a strong base. The hydroxides of group 2nd elements like Sr, Ba and Ca can form strong base.
$\mathrm{Cu(OH)_2}$ is a weak base. It dissociate in very small amount on adding to water. Mostly of part is insoluble.
BaO is a strong base because it act as a very good proton acceptor.
$\mathrm{Ca(OH)_2}$ is a strong di-acidic base. It can completely ionize in water. It is also known as slaked lime.
$\mathrm{Pb(OH)_2}$ is a weak base as it is rarely soluble in water and form $\mathrm{Pb^{2+}}$ ions in weak acidic solution.
MgO act as an basic oxide as it can produce basic Mg(OH)2 on mixing in water.
$\mathrm{Mg(OH)_2}$ is a strong and di-acidic base. It gets ionized 100% in water solution.
RbOH is a monoacidic base. It is a strong base due to it 100% ionization in water.
BeO is an amphoteric compound. It can act both as an acid and a base.
$\mathrm{Zn(OH)_2}$ is a amphoteric substance. It can act both as acid and a base. On reaction with acid it can act as a base.
NaH is a strong base and dissociate completely on adding to water solution.
CsOH is a strong base. It is a monacidic base. Cesium is more electronegative due to which it act as strong base.
Figure 2: Weak bases
Basic compounds are the compounds which can accept protons from other compounds. Bases are differentiate as Lewis base, Arrhenius base or Bronsted-Lowry base. Basic solutions generally show pH value more than 7.
There are various types of bases like monoacidic, di-acidic, tri-acididc, etc. the strong base is that which can completely dissociate in water. The weak bases are those which get incompletely dissociates in water solution. CsOH, NaOH, RbOH, $\mathrm{Mg(OH)_2}$, etc. are the examples of strong bases. $\mathrm{NH_4OH, Cu(OH)_2, Pb(OH)_2}$, etc. are examples of weak bases.
Q1. How could you determine that the compound is basic in nature?
Ans. If the compound shows the ability to accept protons from other compound it shows a basic nature. Also basic compound is determined due to formation of hydroxide ions in aqueous solution.
Q2. What is di-acidic base?
Ans. The compounds which contain two hydroxide ions and can form bonds with two hydrogen ions are called di-acidic base.
Q3. What happen when basic compound added to water?
Ans. When basic compounds get added to water it get dissociates into ions and if OH- ions form it confirms its basic nature.
Q4. CsOH is a strong or weak base?
Ans. CsOH is a strong base because it can completely dissociate in water and form more OH- ions.
Q5. What is lewis base?
Ans. Lewis base is a species which can donates its electrons to a lewis acid.
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