Question

Concentration of hydronium ions change during dilution of an acid. For true add 0 and for false add 1.

Answer 1

Hint: Hydronium ion is complex formed by the proton released from acid and the water molecule. Upon dilution, the total volume of the solution increases. However, the hydronium ions remain the same. Try to relate the increase in volume to the existing concentration of hydronium ions. By this you can identify if the concentration will change or not.

Complete Solution :
- Dilution is the process of decreasing the concentration of a solute in the given solution. This can be done by simply adding more solvent like adding more water to an aqueous solution.
- It is important to note that in the process of dilution, only solvent is added and not solute substance.
- The same relationship is applicable to gases as well as a vapor that are diluted in air. However, the mixing of gases and vapors is not a simple task unlike the case of liquids.
The relationship can be given as :
${{\text{c}}_{\text{1}}}\text{ x }{{\text{V}}_{\text{1}}}\text{ = }{{\text{c}}_{\text{2}}}\text{ x }{{\text{V}}_{\text{2}}}$

Where,
${{\text{c}}_{\text{1}}}$ is the initial concentration of solute
${{\text{c}}_{2}}$ is the final concentration of solute
${{\text{V}}_{\text{1}}}$ is the initial volume of solution
${{\text{V}}_{2}}$ is the final volume of solution

- We will now apply the above formula to answer the question. Dilution of acid by adding the solvent increases the volume of the solution. However, the amount of solute remains the same.
- Due to this the final concentration of the hydronium ions upon dilution will be lesser than the initial concentration.
Therefore, the statement concentration of hydronium ions changes during dilution of an acid is true and the correct answer is '0'.

Note: Dilution of an acid increases its conductivity. This is because upon addition of extra solvent, the volume for the acid to dissociate increases. This is the reason why even weak acids dissociate completely at infinite dilution.