Question

Which one is stronger acid $HCl$ or ${H_2}S{O_4}$ .

Answer 1

Hint : An acid is any hydrogen-containing substance that is capable of donating a proton that is a hydrogen ion to another substance. A base is defined as a molecule or ion able to accept a hydrogen ion from an acid. Acidic substances are identified by their sour taste. Acids are known to turn blue litmus red. Bases are identified by their bitter taste and a slippery texture. Bases are known to turn red litmus blue.

Complete Step By Step Answer:
As we know, acids are hydrogen containing substances that are capable of donating ${H^ + }$ ions.
Hence, both $HCl$ and ${H_2}S{O_4}$ are strong acids when compared to other acids.
When we dissolve $HCl$ in water , it dissociates completely into ${H^ + }$ and $C{l^ - }$ ions .When we dissolve ${H_2}S{O_4}$ in water it dissociates partially into ${H_3}{O^ + }$ and $HSO_4^ -$ ions respectively.
However, $HCl$ is stronger than ${H_2}S{O_4}$ .This is mainly because of the difference in the basicity of both the acids .The pKa of $HCl$ is known to be $- 6.3$ and that of ${H_2}S{O_4}$ is $- 3.0$ .These values tells us that $HCl$ is more acidic as it donates a proton easily.
The pKa value tells us how many acidic ions a substance will produce in a solution. It indicates how many protons dissociate to form hydronium ions. The lower the pKa, the stronger the acid will be.
Hence, we can say that $HCl$ is more acidic than ${H_2}S{O_4}$ .

Note :
Litmus indicator solution is known to turn red in acidic solutions and blue in alkaline solutions. It turns purple in neutral solutions. Litmus indicator solution is usually used to determine the acidity or basicity of a solution.