Question

Which are the general properties of Bronsted acids?
This question has multiple correct options
A. They turn litmus red
B. They react with alkalis
C. They burn the skin
D. They contain H-atom replaceable with metal

Answer 1

Bronsted and Lowry proposed the Bronsted Lowry theory of acid base independently in 1923. It states that:
-An acid donates proton/hydrogen ions
-A base accepts protons/hydrogen ion

Complete step by step answer:
-So according to Bronsted-Lowry, acids and bases are defined by their proton donation or acceptance. A common bronsted reaction example is ammonia with water.
$N{H_3} + {H_2}O \to N{H_4}^ + + O{H^ - }$
-Here ammonia accepts ${H^ + }$so it's a bronsted base, and water donates ${H^ + }$ so it's bronsted acid. After the reaction,$N{H_4}^ +$ is called conjugate acid and the other called conjugate base. The terminology of the conjugate acid base can be understood if you reverse the reaction. Here,$N{H_4}^ +$ can give a proton hence it becomes an acid (in reverse reaction) and vice versa.
-Now, since bronsted acids are actual acids and give hydrogen ions, they turn litmus paper red.
-Alkalies have $O{H^ - }$ groups which can accept protons of bronsted acids and thus they react with alkalis.
-Bronsted acids by definition have hydrogen ions which when reaction with active metals is displaced and ${H_2}$ gas is released.
-But all bronsted acids are not strong. Strong acids are those which completely dissociate into ionic form when mixed in water like HCl. When HCl is added to water, it completely dissociates to ${H^ + }$ and $C{l^ - }$. It's a bronsted acid too as it releases ${H^ + }$. But $C{H_3}COOH$ is also a bronsted acid but it doesn't completely dissociate. $C{H_3}COOH$ gives $C{H_3}CO{O^ - }$ and${H^ + }$, but not completely and exists in equilibrium. Thus bronsted acids involve weak acids also, as they give ${H^ + }$ ions. But only strong acids can burn the skin, not weak acids. As said above, acetic acid doesn't burn the skin, even though it's a bronsted acid.

So the correct answer is options A, B, and D.

Note:

The compounds which act as acid in some reactions and base in other reactions are called amphoteric. For example, water is amphoteric and can act as both a Bronsted acid and a Bronsted base.