Calculations in pH and pOH I

 Hello fam! You must have noticed that there was no lesson updated on our page yesterday. This is due to the fact that I have been ill since the weekend and I am currently taking as much rest as possible. I am recovering gradually. I was advised to take out the whole of yesterday to rest hence I was of duty and couldn’t deliver the lesson for yesterday. 


Like I said in on Sunday, we shall look at mathematical examples of pH, pOH, pKa and pKb. Let’s get started with two examples today.

Example 1;

Find the pH of 0.0025 M HCl solution

Solution;

The first thing that must come to our mind is that HCl is a strong acid hence it completely dissociates in water. Since it dissociates completely, we do not need an ICE table in order to determine the pH. The ICE table would otherwise be necessary when we are dealing with a weak acid.


We now use the formula;

pH = -log[H^+]

Where we have;

[HCl] = [H^+] = [Cl^-] =  0.0025 M 

pH = -log(0.0025 M)

pH = 2.6


Example 2;

What is the hydrogen ion concentration of a solution of pH 8.34?


Solution;

Let us recall that the basic mathematical definition of pH is;

pH = -log(H^+)

Taking the antilogarithm;

(H^+) = Antilog (-pH)

= Antilog (-8.34)

=4.57 * 10^-9 M 

We shall take further examples for the next four days after which we shall move on to another topic.


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