Question

An aqueous solution of potash alum gives
(A) two types of ions
(B) only one type of ion
(C) four types of ions
(D) three types of ions

Answer 1

In order to give the number of ions which are formed when dissolved in water, we must be aware of what a potash alum is. Potash alum is a chemical compound having a chemical formula of ${K_2}S{O_4}.A{l_2}{(S{O_4})_3}.24{H_2}O$. The IUPAC name for potash alum is Aluminium potassium sulphate dodecahydrate.

Complete Solution :
- Let us first see the potash alum. Potash alum is a chemical compound with the chemical formula of ${K_2}S{O_4}.A{l_2}{(S{O_4})_3}.24{H_2}O$. Potash alum is also known as Fitkari. The IUPAC name for potash alum is Aluminium potassium sulphate dodecahydrate. Potash alum is the most important constituent of Alum which is one of the most important coagulants used for the treatment of water. Let us now see some of the properties of Potash Alum. Potash alum is a crystal with octahedral structure. It is a present as a colourless solid. It is highly soluble in ${H_2}O$. Potash alum is acidic in nature and it can change the blue litmus paper into red. The taste of potash alum is astringent. Potash alum being a double salt of ${K_2}S{O_4}$ and $A{l_2}{(S{O_4})_3}$ will give three ions such as $A{l^{3 + }}$ , ${K^ + }$ and $SO_4^{2 - }$ when dissolved in water.
So, the correct answer is “Option D”.

Note: Potash alum can be used for various purposes such as
- Tanning- mainly used for leather tanning.
- Used for dyeing
- Fire retardant
- Blocking chemicals
- Used in medicines as an astringent and antiseptic
- For Culinary purposes.