To drive the reaction towards the product (ester), then add a bit more acid.
You need to add enough acid to keep the pH slightly acidic.
In your equation, we are adding nitric acid to this material.
When one adds acid or base to a buffer the ratio of the two concentrations change.
Be aware that when you add acid to the cooking water, as with juices, the rice takes longer to cook.
Clean filtered air still usually contains CO2, which can add acid.
Adding acid would be like touching it with a dry sponge that sucks up some of the water.
I also believe that adding weak acid to copper sulfide will not do much of anything.
Milk fat is separated from proteins by adding sulfuric acid.
The problem is if you add too much acid.