Question

What is meant by strong bases? Classify the following into strong bases and weak bases.
$N{H_4}OH$ , $Ca{\left( {OH} \right)_2}$ , $NaOH$ , $KOH$ , $Mg{\left( {OH} \right)_2}$ .

Answer 1

Hint: Bases are the chemical species that release $O{H^ - }$ ions when dissolved in water. These can neutralize acid by reacting with hydrogen ions. Acids and base together react to form salts.

Complete step by step solution:
As we know bases are the substances which release $O{H^ - }$ ions when dissolved in water. Strong bases are those which get completely ionized when dissolved in water, i.e. it gets completely dissociated into ions. Whereas weak bases are those which get partially dissociated when dissolved in water. These bases are generally less reactive than strong bases. Also their electrical conductivity is lower than strong bases. $pH$ of strong bases lies between $10 - 14$ and for weak bases it lies between $7.3 - 10$ .
$N{H_4}OH$ is ammonium hydroxide. It is also known as ammonia water, ammonia solution, ammonia liquor, aqua/aqueous ammonia. It does not get completely ionized when dissolved in water, so it is considered a weak base.
$Ca{\left( {OH} \right)_2}$ is calcium hydroxide. It is also called slaked lime or hydrated lime. It dissociates completely when dissolved in water, so it is considered a strong base.
$NaOH$ is sodium hydroxide. It is also known as caustic soda. It dissociates completely when dissolved in water, so it is considered a strong base.
$KOH$is potassium hydroxide. It is also known as caustic potash. Like $NaOH$ it is a strong base.
$Mg{\left( {OH} \right)_2}$ is magnesium hydroxide. It does not get completely ionized when dissolved in water, so it is considered a weak base.
According to our classification: Strong base - $NaOH$, $KOH$, $Ca{\left( {OH} \right)_2}$
Weak base - $N{H_4}OH$, $Mg{\left( {OH} \right)_2}$

Note: To solve such questions write the symbol of cation on the left side and write its charge just below it. Similarly write the symbol of anion on the right side and its charge below it. Charge on the anion will be equal to the number of atoms of cation and charge of cation will be equal to the number of atoms of anion. Combining all these things we will get the chemical formula of the desired compound. Also remember to reduce the molecules to the smallest integer.