briefly explain why excess HCl and NaOH solutions must be collected for treatment before disposal, but the titration solution from a completed titration can be safely poured into the drain, diluting with a large amount of water.
because
Excess HCl (hydrochloric acid) and NaOH (sodium hydroxide) solutions need to be collected for treatment before disposal due to their corrosive and potentially harmful nature. Here's why:
1. Excess HCl Solution: Hydrochloric acid is a strong acid. When it comes into contact with surfaces, such as pipes or drains, it can cause corrosion and damage. Therefore, it is essential to collect the excess HCl solution separately and treat it properly to neutralize its acidity before disposal. This prevents potential harm to the environment and infrastructure.
2. Excess NaOH Solution: Sodium hydroxide is a strong base. If excess NaOH solution is poured down the drain, it can increase the pH levels of water dramatically, potentially causing harm to aquatic life. Therefore, collecting and treating the excess NaOH solution ensures that it can be neutralized before being safely disposed of, preventing any negative impact on the environment.
On the other hand, the titration solution from a completed titration is typically safe to be poured into the drain, but with precautions. Here's why:
1. Dilution with Water: The titration solution, which usually consists of water and the analyte being titrated, is mixed with a small amount of standardized solution (e.g., HCl or NaOH) during the titration process. Once the titration is complete, the quantity of standardized solution added in comparison to the total volume of the solution is usually minimal. Pouring this solution down the drain with a large amount of water helps to dilute it to safe concentrations.
2. Neutral Nature: The titration solution is usually neutral or close to neutral after the titration is completed. The addition of the standardized solution during the titration process aims to reach the equivalence point where stoichiometrically, the acid and base quantities balance, resulting in a neutral solution (pH 7). Therefore, the titration solution does not pose significant hazards, and diluting it with water further reduces any potential risk before disposal.
However, it is always recommended to check local regulations and guidelines regarding the disposal of chemicals and follow proper procedures accordingly.