Question

How do you determine pH of a solution ?

Answer 1

It helps us to define how acidic or basic the solution is. If the pH of the solution $\;7$is less than, then it is acidic and if the pH of the solution is more than $\;7$, then it is the basic solution. In the same way, if the pH of the solution is equal to $\;7$, then the solution is neutral.

Complete step by step answer:
pH is a measure of in what way acidic or basic a chemical solution is. The pH measure runs from $0{\text{ }}to{\text{ }}14$—a value of seven is measured neutral, less than seven acidic, and greater than seven basic.
pH is the negative base $10$ logarithm (on a calculator) of the hydrogen ion concentration of a solution. To calculate it, take the log of a given hydrogen ion concentration and converse the sign.
Here's a more detailed review of how to compute pH and what PH means with high opinion on hydrogen ion concentration, acids, and bases.
Review of Acids and Bases
There are some ways to describe acids and bases, but pH definitely only refers to hydrogen ion concentration and is pragmatic to aqueous (water-based) solutions. While water dissociates, it produces a hydrogen ion and a hydroxide. See this chemical equation lower.
${H_2}O{\text{ }} \leftrightarrow {\text{ }}{H^ + }\; + {\text{ }}O{H^ - }$
When conniving pH, remember that denotes molarity, M. Molarity remains expressed in units of moles of solute per liter of solution. If you are specified concentration in any other unit than moles (mass percent, molality, etc.), renovate it to molarity in instruction to use the pH formula.
The relationship between pH and molarity can be articulated as:
${K_w}\; = {\text{ }}\left[ {{H^ + }} \right]\left[ {O{H^ - }} \right]{\text{ }} = {\text{ }}1x{10^{ - 14}}\;$at $25^\circ C$
for pure water $\left[ {{H^ + }\left] {{\text{ }} = {\text{ }}} \right[O{H^ - }} \right]{\text{ }} = {\text{ }}1x{10^{ - 7}}$
${K_w}\;$is the dissociation constant of water
Acidic solution: $\left[ {{H^ + }} \right]{\text{ }} > {\text{ }}1x{10^{ - 7}}$
Basic solution:$\;\left[ {{H^ + }} \right]{\text{ }} < {\text{ }}1x{10^{ - 7}}$
Example- Find the pH of a $0.03{\text{ }}M$ solution of hydrochloric acid, HCl.
Recollect, Hydrochloric acid is a strong acid that dissociates conferring to a $1:1$ molar ratio into hydrogen cations and chloride anions. So, the concentration of hydrogen ions is accurately the same as the concentration of the acid solution.
Sol:
$\left[ {{H^ + }\;} \right] = {\text{ }}0.03{\text{ }}M$
$pH{\text{ }} = {\text{ }} - {\text{ }}log{\text{ }}\left( {0.03} \right)$
$pH{\text{ }} = {\text{ }}1.5$

Note:
To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). The pH is then calculated with the expression: $pH\; = {\text{ }} - {\text{ }}log{\text{ }}[{H_3}{O^ + }]$