Question

If acetic acid and hydrochloric acid of the same concentration are taken, which among the two is a stronger acid and why?

Answer 1

Hint: since the concentrations are the same of both acids, just look upon the dissociating nature and the one which is dissociating completely will be stronger acid. One of the acids dissociates partially and the other dissociates completely. So fully dissociating will give out more Hydrogen ions in the solution and therefore will be the stronger one.

Complete Step by step answer:
In the question, the two acids are compared and both are having equal concentration. Now we need to find out which one is the stronger acid.
A strong acid is defined as the one which dissociates completely in the solution and gives out all of its \[{H^ + }\]ion very fast and whereas a weak acid is defined as the one which dissociates partially when dissolved and does not give its all of its \[{H^ + }\] ion very easily.
Few examples of strong acids are like \[HCl,{\text{ }}{H_2}S{O_4},{\text{ }}HN{O_3}\] etc. and examples of weak acids are \[C{H_3}COOH\], Oxalic acid etc.
Now in this question the acid \[HCl\] and \[C{H_3}COOH\] are taken along with equal concentration and we know that acidity of solution will depends on the amount of \[{H^ + }\] ions it is having.
Now the concentration is the same then we will look at their nature i.e. strong and weak and we know \[HCl\]is strong acid and \[C{H_3}COOH\] is a weaker acid.
Because the HCl dissociates as: \[HCl{\text{ }} \to {\text{ }}{H^ + }{\text{ }} + {\text{ }}C{l^ - }\]
Whereas acetic acid dissociates as \[C{H_3}COOH{\text{ }} \rightleftharpoons {\text{ }}C{H_3}CO{O^ - }{\text{ }} + {\text{ }}{H^ + }\]
So, we see that acetic acid is dissociating partially and Hydrochloric acid is dissociating completely which makes it a strong acid because it will give out a greater number of \[{H^ + }\] ions.
(Concentration is the same so we will look upon the dissociating nature and the one giving higher \[{H^ + }\] ions will be stronger one.)

Therefore, the correct answer is Hydrochloric acid will be stronger one.

Note: There are few acids which should be known to students like basic examples of strong acid, weak acid and similar in base i.e. strong base, weaker base. If we want to compare their strength, it could be done on the basis of pH in which we use concentration of Hydrogen ions.