Question

pH of a solution is $5.5.$ The $\left[ {{H}^{+}} \right]$ concentration of the solution is $\left[ antilog\text{ }of\text{ }0.5=3.125 \right]$
(A) $3.125\times {{10}^{-5}}M$
(B) $3.125\times {{10}^{-6}}M$
(C) $3.125\times {{10}^{-4}}M$
(D) $3.125\times {{10}^{-7}}M$

Answer 1

Hint: We know that by the definition of pH which is the measure of the hydrogen ion concentration or the acidity of the solution, the pH of the solution is calculated as the negative log of hydrogen ion concentration.

Complete answer:
The pH of the solution is the measure of the hydrogen ion concentration which in turns is the measure of its acidity. The pure water dissociates into equal concentrations of hydrogen ion and hydroxyl ion. When the hydrogen ion is in excess, the solution is considered as acidic and when the hydrogen ion is limited (hydroxyl ion) is in excess then the solution is basic in nature. 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. When conniving pH, remember that denotes molarity, Molarity remains expressed in units of moles of solute per liter of solution.
$pH=-log\left[ {{H}^{+}} \right]$
Thus, after substituting we get; $5.4=-log\left[ {{H}^{+}} \right]$
$~\left[ {{H}^{+}} \right]=antilog\left( -5.5 \right)=3.125\times {{10}^{-6}}M$
Therefore, the correct answer is Option B.

Note:
Remember that 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.