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

Hint: 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.