Coupon Accepted Successfully!


Strong Acids and Bases

Strong acids such as HNO3, HCl, and HI dissociate almost completely. If we were asked to predict the direction of such a dissociation reaction, we should say that the direction of reaction favors the dissociation of the acid. The dissociation of HI is shown below:

image\24990 ch 9.png

Since there is complete dissociation for every mole of HI present, equal number of hydronium ions are formed. You may be wondering whether protons can be supplied by the water molecules that are present. Usually this supply is negligible (the self-ionization of water is extremely low) compared to the concentration of the strong acid present. But this may not be always the case. Think about an instance when the proton contribution of water is significant in an acidic solution such as that of hydrogen iodide. When you have a strong acid solution which is very dilute, water does contribute protons significantly compared to that of the strong acid present.
Now let's consider a strong base such as potassium hydroxide. Let's say the solution is 1 x 10–3M. Since KOH is a strong base, it dissociates completely. So we can confidently say that the concentration of hydroxide-ion formed is also 1 x 10–3M. Just like the strong acid, we can ignore the possibility of hydroxide-ion formation from water, since the self-ionization of water is negligible. Since the OH concentration is 1 x 10–3, the pOH is 3. From this, we can say that the pH of this solution is close to 11, since pH + pOH = 14.


A pH value below 7 is acidic, a pH value above 7 is basic, and a pH value 7 is neutral.

Table 9-1

Some Examples Of Strong Acids
Sulfuric acid H2SO4
Nitric acid HNO3

Hydrochloric acid

Hydrobromic acid HBr
Hydroiodic acid HI
Perchloric acid HClO4
Chloric acid HClO3

Some Examples Of Strong Bases

Lithium hydroxide LiOH
Sodium hydroxide NaOH
Potassium hydroxide KOH
Cesium hydroxide CsOH
Calcium hydroxide Ca(OH)2
Strontium hydroxide Sr(OH)2
Barium hydroxide Ba(OH)2

Test Your Skills Now!
Take a Quiz now
Reviewer Name