Question

How do we dilute concentrated hydrochloric acid to give $10\% \;HCl$?

Answer 1

An acidic solution which has a small quantity of water and a large quantity of acid is referred to as concentrated acid while the acidic solution in which the amount of water is more than the amount of acid is known as dilute solution.

Complete answer:
To dilute a concentrated acid, we should add the concentrated acid to water slowly with continuous stirring. The dilution of the concentrated hydrochloric acid to prepare $10\% \;HCl$ can be done in following ways:
1. $\% \dfrac{V}{V}$ method:
In this case, the concentration of the solution is expressed in terms of volume. So, when 10mL of concentrated hydrochloric acid is diluted with 90mL of water, then the total volume of the solution will be 100mL and therefore, we would express the concentration of the solution as $10\% \dfrac{V}{V}\;HCl$.
2. $\% \dfrac{W}{W}$ method:
In this case, volume of the considered chemical is disregarded and the concentration of the solution is expressed in terms of weight. So, if we would take 10g of concentrated hydrochloric acid in 90g of water then we can express it as $10\% \dfrac{W}{W}\;HCl$.
vThus, we can conclude that in order to give $10\% \;HCl$, we would need to dilute the concentrated hydrochloric acid in water in the ratio $1:9$.**

Note:
It is important to note that we should never add water to acid because the reaction is highly exothermic and the solution may splash out onto our skin which is highly corrosive and may cause severe burns to our skin. Hence, we should always add acid to water slowly.