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Strong bases form an integral part of the chemistry syllabus. These are the bases that get wholly dissociated in water to release OH– ions. The properties of the strong bases help to determine their behaviour when mixed with another strong base or a weak acid. Further, it is easy to find the pH of the mixture of a weak acid and strong base based on these properties.

Let us know all about the mixture of two strong bases, the pH of the mixture of these strong bases, etc. Not to miss are quick, frequently asked questions at the end that help students overcome their doubts without the need for any additional learning material. Let us start with the definition of solid bases.

What is a strong base?

Bases tend to release OH– ions more than the H+ ions when added to water. Hence, the difference between acids and bases is that acids release more H+ ions while bases release more OH- ions. The strength of the strong base depends on the proton accepting capacity of the base when dissolved in the aqueous solution of water. 

Some of the strong bases are:

  • Strontium hydroxide or Sr(OH)2
  • Barium hydroxide or Ba(OH)2
  • Calcium hydroxide or Ca(OH)2
  • Caesium hydroxide or CsOH
  • Rubidium hydroxide or ROH
  • Lithium hydroxide or LiOH
  • Potassium hydroxide or KOH
  • Sodium hydroxide or NaOH

A mixture of two strong bases

Let us understand the mixture of two strong bases, base 1 and base 2.

Let V1 be the volume and N1 be the normality of the strong base 1.

Let V2 be the volume and N2 be the normality of the strong base 2.

The ionic concentration of base 1 and base 2 is represented by N1V1 and N2V2.

The concentration of H+ ions is N = N1V1 + N2V2 / V1 + V2.

The concentration of OH- ions is N = N1V1 + N2V2/ V1 + V2.

[ H+ ] = (10)- 14 / OH-

The pH of the mixture of a weak acid and strong base

The quick steps to analyse the pH of the mixture of a weak acid and strong base are:

  • Determine the type of acids or bases used in the formation of the mix.
  • Write the balanced equation for the reaction to calculate the number of molecules.
  • Calculate the equilibrium composition of the mix.
  • Calculate the pH of the mixture of a weak acid and strong base.

Example of strong base: LiOH – lithium hydroxide

LiOH or lithium hydroxide is a strong base. No moles of LiOH get undissolved in water, and it dissociates in water completely. It releases large amounts of the OH- ions which have the tendency to accept the protons. This accumulation of the proton acceptors in the aqueous solution of lithium hydroxide makes it a strong base.

The chemical equation indicating the dissociation of Lithium ions in water to form an aqueous solution is:

LiOH + H20 à Li+ (aq) + OH- (aq)

It is only a forward reaction, and there is no possibility of a backward reaction in the case of Lithium hydroxide. Further, Li+ being the weak conjugate acid of LiOH, it doesn’t have the ability to react with OH- ions or the water molecules. Hence, the split ions Li+ and OH- remain in the aqueous solution without responding further.

Conclusion

The overview of the mixture of two strong bases helps determine their behaviour in the aqueous solution. The strong bases dissociate completely in the water while releasing OH- ions. The strong bases can be derived from removing protons from neutral molecules. All strong bases are suitable proton acceptors as OH- can be fetched by eliminating the H+ ions from H2O.

The strength of the base refers to the ability to release OH- ions or accept the protons from the H20 molecule. Further, it is easy to understand the pH of the mixture of a weak acid and strong base, which depends on the elevated concentrations of the weak acid or the strong base.Â