If I had a pH 10 in a 100ml solution of water and 93% sodium hydroxide how much mg/l of 93% sulfuric acid would we need to use to reach a pH of 4.

From my dated college chem books and a lot of google searching i know

1.) One mole of sulfuric acid will neutralize two moles of sodium hydroxide, as follows:

$$\ce{2NaOH + H2SO4 → Na2SO4 + 2H2O}$$ (the result is two water and one salt)

2.) 1 Gallon = 3785.41 mL or 378.541 L

3.) pH + POH = 14

4.) In one minutes time we will have 100 gallons or 378541ml (100 gallons * 3785.41 = 378541 mL)

5.) pH = 10 (of our water/sodium hydroxide solution.)

6.) The hydronium ion concentration can be found from the pH by the reverse of the mathematical operation employed to find the pH.

 10^(-pH) = hydronium ion concentration

 hydronium ion concentration = 10^-10 = 1e-10 M or 0.0000000001 mol/l

 378.541 L * 0.0000000001 mol/l = 3.78541e-8 moles

 we need a hydronium ion concentration of 10^-4 which is 0.0001 mol/l

How do i put this all together?


closed as off-topic by R.M., M.A.R., airhuff, Buttonwood, Todd Minehardt May 18 '17 at 20:29

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  • $\begingroup$ If you could use simple step by step with labeling each step would be amazing, I know I am asking a lot and I do not know if this is possible given my lack of variables. Any help is much appreciated. $\endgroup$ – ID10T_ERROR May 17 '17 at 21:14
  • $\begingroup$ After more research I have been told this is a titration curve problem and my concentration of sodium hydroxide needs to be known? $\endgroup$ – ID10T_ERROR May 18 '17 at 3:30
  • $\begingroup$ This is impossible to calculate unless you know the buffering capacity of the input. At best you could neutralize the added sulfuric acid, but that would only bring you back to around the input pH. (And you're also correct that it would be good to know the concentration of the sodium hydroxide solution.) $\endgroup$ – R.M. May 18 '17 at 17:49
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    $\begingroup$ Also, why are you asking us (random yahoos on the Internet that we are)? This sounds like a situation where you really should be having a certified Chemical Engineer signing off on this process. If you have a Chemical Engineer involved, I'd recommend asking them to do the calculations, to make sure you get them right for the particulars of your situation. If you don't have one involved in the process, I'd suggest you recommend to your boss that you hire one as a consultant, to make sure you don't mess things up in a holy-shit-we-are-getting-a-massive-fine/injured-someone type way. $\endgroup$ – R.M. May 18 '17 at 17:56
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    $\begingroup$ I'm voting to close this question as off-topic because it's asking about a situation which requires a licensed professional. We can not safely answer questions for your specific situation and you should consult someone with the appropriate certifications. $\endgroup$ – R.M. May 18 '17 at 18:00