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Name: Kerry
Status: educator
Grade: N/A
Location: NJ
Country: N/A
Date: October 2006

Question:
In a neutralization reaction of NaOH and H2SO4, because there are 2 acidic Hydrogens do you multiply the number of moles by 2?



Replies:
Kerry, Yes, that should work with sulfuric acid and sodium hydroxide, but not all acids and bases are strongly acidic or basic. Acids like acetic acid (vinegar), carbonic acid and others do not dissociate 100% and weak bases like sodium bicarbonate do not dissociate 100% either. If you mix a weak acid and base together and just used mole ratios, then your pH would be off (not neutral) because you are creating a buffer system and would need to titrate to a particular pH with a strong acid or base. Also, the second ionization of sulfuric acid is not anywhere near as strong as the first, but NaOH will neutralize it. If you are neutralizing these substances for disposal, then you will be fine with a pure mole ratio, but if you are doing pH sensitive chemistry, then I would check the pH with a probe first just to make sure.

Matt Voss


I am not sure exactly what neutralization reaction you are referring to. If you start with let's say 1 molar H2SO4 and start titrating it with 1 molar NaOH the pH will start to increase. The degree of ionization of the two hydrogens in H2SO4 is different. When you have added about 1 mol of NaOH you will observe a "break" in the pH vs. amount of NaOH added. That is due to the neutralization of the first H+ in the sulfuric acid. What remains is largely HSO4(-1). If you then continue to add another mol of NaOH the pH will continue to increase, and when you have added a second mol of NaOH you will again see a "break" in the pH vs. amount of NaOH added. This is due to the neutralization of the second H+ in the sulfuric acid. What is left then is a solution of 2 Na(+1) ions and 1 mol of SO4(-2). If I have correctly understood your question, then the short answer is yes.

Unknown


Kerry,

Since both protons in H2SO4 are acidic protons relative to NaOH, both H's will react with NaOH. Thus, a balanced chemical reaction is written as:

H2SO4 + 2NaOH = Na2SO4 + 2H2O

This indicates that 2 moles of NaOH are needed to fully react with 1 mole of H2SO4 (per mole of reaction).

Greg (Roberto Gregorius)


Yes. To neutralize 2 moles of sulfuric acid requires 4 moles of sodium hydroxide.

Richard Barrans
Department of Physics and Astronomy
University iof Wyoming



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