Question

Which has a higher $pH$ value-$0.01M$ $NaOH$ or $0.1M$ $NaHC{O_3}$?

Answer 1

$pH$ is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions are measured to have lower $pH$ values than basic or alkaline solutions. The $pH$ scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution. This is because the formula used to calculate $pH$ approximates the negative of the base $10$ logarithm of the molar concentration of hydrogen ions in the solution.

Complete answer:
$pH$ is a measure of how acidic or basic water is. The range goes from $0$ to $14$, with $7$ being neutral. pH of less than $7$ indicates acidity, whereas a pH of greater than $7$ indicates a base. $pH$ is really a measure of the relative amount of free hydrogen and hydroxyl ions in the water.
To calculate the $pH$ of $0.01M$ $NaOH$
First we calculate the $pOH$, because when we dissolve the $NaOH$ in water $NaOH$ dissociates into $N{a^ + }$ and $O{H^ - }$.
$\Rightarrow pOH = - \log [O{H^ - }]$
$\Rightarrow pOH = - \log [0.01] = 2$
We know that the
$\Rightarrow pH + pOH = 14$
$\Rightarrow pH = 14 - 2 = 12$
So, the $pH$ of $0.01M$ $NaOH$ is $12$
And the $pH$ of $0.1M$ $NaHC{O_3}$ is $8.3$
So, the $pH$ of $0.01M$ $NaOH$ is higher than $0.1M$ $NaHC{O_3}$.

Note:
Indicators may be used to measure $pH$, by making use of the fact that their color changes with $pH$.Visual comparison of the color of a test solution with a standard color chart provides a means to measure $pH$ accurate to the nearest whole number. More precise measurements are possible if the color is measured spectrophotometrically, using a colorimeter or spectrophotometer. Universal indicator paper is made from absorbent paper that has been impregnated with universal indicator. Another method of measuring $pH$is using an electronic $pH$ meter.