Synthetic Solution: How much nitric acid to add?

[sorelN65]

I am making a synthetic solution to imitate a real life situation. I am adding calcium nitrate to the solution to meet a target calcium level of 334 ppm. However, using excel calculations the amount of calcium nitrate that is needed imparts a total of 522 ppm calcium. I am also adding 100 ppm calcium carbonate which will increase the levels of calcium. My supervisor said I need to add nitric acid to lower the calcium imparted by the calcium nitrate. How and why does that work? and what calculation do I need to do to figure out how much nitric acid I need to add? I have attached the excel spreadsheet I am working with.

[scooke]

Dear Sorel,

Adding nitric acid is neither required in the first place, nor would using it in any way decrease the amount of calcium available in the solution at those concentrations.  It is not clear whether your nitrogen values are for the compounds indicated or as nitrogen contributed by those compounds.

I’m not quite sure where you are going with this – it might be best to ask for more direction from the instructor. From your

data sheetI do NOT see any need for carbonate, so it is really just a way to add additional calcium. The ration of calcium to nitrate in Calcium Nitrate (Ca(NO₃)₂) is 40:124g, so adding 183mg of nitrate means that 59.0mg of calcium would be included. Thus, a “make up” of (394-59)=335mg of calcium would be needed for the target concentration. This would then come from 837.5mg of calcium carbonate (Ca:CO3 of 40:60). Nitric acid is not required at all.

Best regards,

Steven