Question

Determine the hydroxide ion concentration in a solution that is: 1 × 10-4 M HCl. (kw = 1.0 X10-14)

Answer 1

Answer: The hydroxide ion concentration in a solution is $1\times 10^{10}M$

Explanation:

pH or pOH is the measure of acidity or alkalinity of a solution.

pH is calculated by taking negative logarithm of hydrogen ion concentration.

$pH=-\log [H^+]$

$HCl\rightarrow H^++Cl^{-}$

According to stoichiometry,

1 mole of $HCl$ gives = 1 mole of $H^+$

Thus $1\times 10^{-4}$ moles of $HCl$ gives =$\frac{1}{1}\times 1\times 10^{-4}=1\times 10^{-4}$ moles of $H^+$

$K_w=[H^+][OH^-]$

$10^{-14}=[1\times 10^{-4}][OH^-]$

$[OH^-]=1\times 10^{10}M$

Thus the  hydroxide ion concentration in a solution is $1\times 10^{10}M$