Answer and Explanation:
To determine how much solid sample you should add to reach the second endpoint at 15 mL of NaOH, we need to understand the concept of the second endpoint and how it relates to the concentration of the solid sample.
The second endpoint is reached when all of the analyte has reacted with the titrant. In this case, the analyte is the solid sample, and the titrant is NaOH. The reaction between the solid sample and NaOH can be represented as follows:
Solid Sample + NaOH → Reaction
To calculate the amount of solid sample needed to reach the second endpoint, we need to consider the stoichiometry of the reaction. The stoichiometry tells us the ratio of reactants in the balanced chemical equation.
However, since we don't have the balanced equation or any additional information about the reaction, it's not possible to provide a specific answer to the question. We would need more details, such as the molar ratio between the solid sample and NaOH, to calculate the exact amount of solid sample needed.
If you have more information or specific values related to the reaction, please provide them, and I'll be happy to assist you further in calculating the amount of solid sample required.