Question

I am encountering an issue in my laboratory. My supervisor and I are currently faced with the task of neutralizing a volume of 60 liters of Aqua Regia, which contains suspended metals, at a concentration of 2% or lower. Our current approach involves using Granular Sodium Hydroxide (NaOH) as a neutralizing agent. However, we have observed that we often end up using excessive amounts of NaOH, resulting in an overly basic solution. Therefore, I seek guidance on the appropriate quantity of NaOH required to neutralize the Aqua Regia effectively.

Furthermore, I would like to inquire about the viability of preparing an aqueous solution of NaOH prior to its addition to the 60-liter drum. Will this method enhance the neutralization process?
Any advice is greatly appreciated.
EDIT: At my job we digest silver alloys and we use 10 mL of 30% HNO3 and 5 mL Concentrated HCl. When we filter to collect AgCl we use DI H2O and the amount that we use is not the same through out all of the filtering. So the concentration of the Aqua Regia is most like below 2%. I just used 2% as a guess really.

Answer 1

To neutralize Aqua Regia effectively, it is important to determine the exact concentration and perform a titration if necessary. Preparing an aqueous solution of NaOH before adding it to the drum can enhance the neutralization process.

Step-by-step explanation:

The task of neutralizing Aqua Regia, which contains suspended metals, can be approached by using Granular Sodium Hydroxide (NaOH) as a neutralizing agent. However, excessive amounts of NaOH often lead to an overly basic solution.

To determine the appropriate quantity of NaOH required, it is crucial to know the exact concentration of Aqua Regia. Additionally, preparing an aqueous solution of NaOH prior to its addition to the 60-liter drum can enhance the neutralization process.

To calculate the required quantity of NaOH, the concentration of Aqua Regia needs to be established accurately. If the Aqua Regia concentration is below 2%, it is necessary to perform a titration with a standardized solution of NaOH to determine the amount required for neutralization.

Preparing an aqueous solution of NaOH before adding it to the drum can improve the neutralization process. By dissolving the appropriate amount of NaOH in a known volume of water, you can have better control over the amount being added, allowing for more accurate neutralization.