Question

Ammonia is the most common and well-known weak base. A sample of household ammonia has a pH of 11.8. Determine its concentration

Answer 1

Answer:

The concentration is 1.58*10^-12 M

Explanation:

Step 1: Data given pH of ammonia = 11.8

pH = -log[H+] = -log[H3O+]

Step 2: Calculate the concentration

2H20(l) ⇆ H3O+ + OH-

Kw = [H3O+][OH-]

-pKw = log[H3O+] + log[OH-] = log 10^-14

-14 = log[H3O+] + log [OH-]

14 = - log[H3O+] - log[OH-]

14 = pH + pOH

[H3O+] = 10^-11.8

[H3O+] = [H+] = 1.58 * 10^-12 M

The concentration is 1.58*10^-12 M

Answer 2

The given question is incomplete. The complete question is:

A sample of household ammonia has a pH of 11.50. What is the hydronium ion concentration of this solution?

Answer: The hydronium ion concentration of the solution is $1.58\times 10^{-12}M$

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. Acids have pH ranging from 1 to 6.9 and bases have pH ranging from 7.1 to 14.

$NH_3+H_2O\rightarrow NH_4^++OH^-$

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

$11.8=-log [H^+]$

$[H^+]=antilog(-11.8)$

$[H^+]=1.58\times 10^{-12}M$

Thus hydronium ion concentration of this solution is $1.58\times 10^{-12}M$