 |
 |
Sodium Hydroxide and Sulfuric Acid
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
Click here to return to the Chemistry Archives
| |
Update: June 2012
|
|
