Final answer:
In an acid-base neutralization titration, the unknown concentration of the receiving solution can be calculated because, at the endpoint, the number of moles of acid equals the number of moles of base. Using the known concentration and volume of the standard solution, the concentration of the unknown solution can be calculated.
Step-by-step explanation:
In an acid-base neutralization titration, the unknown concentration of the receiving solution can be calculated because at the endpoint, the number of moles of acid is equal to the number of moles of base due to the stoichiometry of the neutralization reaction. By knowing the volume and concentration of the standard solution (the titrant), one can calculate the number of moles that have been added. Since the moles of acid and base are equal at the endpoint, this information can be used to determine the concentration of the unknown solution using the formula concentration × volume = moles.
It is important to note that different calculations may be involved when dealing with weak acids or bases, taking into account the equilibrium constant and the stoichiometry of the neutralization reaction, but the foundational concept remains that equivalence at the endpoint allows for the determination of the unknown concentration. The endpoint is usually indicated by a color change of an indicator added to the solution or by using a pH meter. For stronger acids and bases, a straightforward stoichiometric calculation can be used once the endpoint is reached.