Question

An acid is added to water to make 30ml of a solution with a $pH$ of $6.5$ if the solution is then diluted the total volume of $300{\text{ }}ml$ what will be the value of $pH$?
A. $6.5$
B. between $6.5{\text{ }}\;and\;{\text{ }}7$
C. $7.5$ because the hydrogen ion concentration is decreased by a factor of $10$
D. either $A$ or $B$depending upon what acid was used but is impossible.

Answer 1

In this question we have to justify the value of $pH$ which changes accordingly when something is added in the solution. As given in the question acid is added to water to make a solution then the solution gets diluted, thus the $pH$values will be changed, as the concentration changes.

Complete step by step solution:
The term “$pH$” is an acronym used for the “potential of hydrogen.” It is a unit of measurement which can be done to represent the concentration of hydrogen ions into a solution. This $pH$ unit was firstly introduced by a biochemist namely Soren Peter Lauritz Sorensen.
When an acid is added to water to make of a solution with a$pH$ of $6.5$ if the solution is then diluted the total volume of $300ml$ then the solution will be diluted and the changes in the $pH$ value takes place.
Thus the $pH$ value of $300ml$ solution is in between $6.5{\text{ }}\;and\;{\text{ }}7$

Hence, option C is correct.

Note: It is usually done to characterize the concentration of hydrogen ions in a solution during titrations. One can also calculate dilution of a solution or a sample by dilution factor which can be done by dividing the final volume by the initial volume of the solution.