Neutralizing nitric acid with sodium bicarbonate

A. Please pull out a chemistry book to check my recollection, but let's see. The reaction is probably:

HNO₃ + NaHCO₃ => NaNO₃ + H₂O + CO₂

If this is correct then it takes one part of sodium bicarbonate to neutralize one part of nitric acid.

5 percent nitric is probably not a whole lot heavier than water, so 100 gallons equals 834 pounds of solution equals 42 pounds of nitric acid.

So the amount of bicarbonate you need is 42 pounds times the molecular weight of bicarbonate divided by the molecular weight of nitric acid. I figure about 56 pounds.

I assume that this is about double-checking the amount you calculated by scaling up from the beaker sized titration you did under a lab hood before you even began dreaming about working with 100 gallons of the stuff :-)

A. John,

The easiest way to answer your question would be to do a small scale experiment (1 gal, or so), then do the math.

Just a follow up point. I'm not sure what (if any) experience you've had at neutralizing. And, while 5% isn't extremely strong, be careful...slowly add the Sodium Bicarbonate to your nitric to see what, if any, reaction you are going to get.

A. Hi Marc,

Your colleague Randal Fowler would have a heart attack (or his dawg would) if he heard YOU saying 'add the bicarb to the acid'. Tut, tut! Mind you ,laws and regs, etc., are made to protect the illiterati ... isn't there a saying LAWS ARE TO BE BLINDLY OBEYED BY FOOLS BUT ACT AS A GUIDE TO WISE MEN?

However, because the nitric was so weak, I, too, would have thought of carefully adding the bicarb to neutralize it.

A. If you don't feel qualified don't do it! Nitric-hydrofluoric acid treatments carry risks and demand knowledge, skills, and protective equipment. Specialists can be contacted for on-site projects like this.

Calculations are only a guide to give you a ballpark estimate of how much chemical to buy. As Marc says, titrating a small volume and scaling up is the way to do it. But 25% nitric and 5% HF would mean you will need about six times as much neutralizer as for a 5 percent solution (I didn't do a real calculation, I just multiplied by 6).

A. Hi Alan,

I would have thought that the best controls to prevent staining is the quality of the rinse water, especially the last two rinses. I would personally use distilled or demineralised water in the final rinses, including the hot rinse. I would control the water by conductivity, keeping the water below 150 microsiemens.

To me the bicarbonate is a neutraliser only and will not prevent staining.

A. Hi Gurudip. Mixes that have been made accidentally like this have no use or value. After accidentally making a dangerous chemical, please don't try to now find a use for it. Neutralize it with baking soda [in bulk on eBay or Amazon [affil links] under careful supervision -- which clearly means not having the people who created it attempt to neutralize it :-)

The neutralization process will gas and foam enormously, so a lot of time will be required. I hope management is carefully investigating this accident and installing at least two separate levels of checks to prevent it from happening again; it could have been a catastrophe. Good luck!

Regards,