Question

What is the difference between a concentrated and a dilute acid?

Answer 1

A concentrated acid is a species whose concentration is (typically) GREATER than `1*mol*L^-1`; whereas a...........

Explanation:

..........whereas a dilute acid is a species whose concentration is LESS than `1*mol*L^-1`. Note that this definition of acidity does not take into account whether protonolysis is complete or incomplete; i.e. `HF` and `HOAc` can BOTH be quite concentrated. Nevertheless, these are both quite weak Bronsted acids, i.e. the equilibrium......

`HX(aq)+H_2O(l)rightleftharpoonsH_3O^+ + X^-`

............lies somewhat to the left.

For sulfuric acid, the equilibrium lies to the right........

`H_2SO_4(aq) + 2H_2O(l) rarr 2H_3O^+ + SO_4^(2-)`

Given the definition advanced above, any solution of `H_2SO_4(aq)` whose concentration is LESS than `0.5*mol*L^-1` with respect to `H_2SO_4(aq)` would therefore be classified as a dilute acid. Why
`0.5*mol*L^-1` and not `1.0*mol*L^-1`. You should check your syllabus with regard to this definition; the cut-off point is arbitrary.

An important practical tip when you deal with conc. acids: when you dilute a strong acid with water IT IS ALWAYS ACID TO WATER, and NEVER WATER TO THE ACID. Why? Because if you spit in strong acid it will spit back.