Loading....
Coupon Accepted Successfully!

 

The Concept of pH

In order to describe the acidity of a solution, scientists have devised the pH scale. The pH is defined as the negative log of the hydrogen-ion concentration.
 
pH = – log [ H+]

 

Example 9-1

What is the pH of a solution having a 1 x 10–2M hydrogen-ion concentration?

 

Solution

The formula for pH is pH = – log [ H+ ]. Substituting in this formula,

 

pH = – log (1 x 10–2) = 2

 

The pH of this solution is 2.
 

We can also find pH if we know the hydroxide-ion concentration.

 

pOH = – log [OH]
 

Since pH + pOH = 14, if we know the pOH, the pH can be easily calculated or vice versa.
 

 

Example 9-2

Find the pH of solution X, if it has a hydroxide-ion concentration of 1 x 10– 8M.

 

Solution

Since the hydroxide-ion concentration is 1 x 10– 8M, the pOH is 8. Since we know that pH + pOH is 14,

 

pH = 14 – 8 = 6

 

The pH value of solution Xis 6.
 





Test Your Skills Now!
Take a Quiz now
Reviewer Name