MadDog5145
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Apparently there is something wrong with that slide (image), but I can't figure out what!
Any chemists out there? Need some help......
- Thread starter MadDog5145
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Apparently there is something wrong with that slide (image), but I can't figure out what!
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It's the yellow background
Should be darker?
Should be darker?
marvin
Headphoneus Supremus
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I think it's in the last line.
Quote:
The equation is:
Quote:
Acetic Acid is the weak acid, so [HA] = 0.03 mol at the start of the rxn.
NaOH is the strong base, so [OH-] = 0.01 mol.
After NaOH reacts with the Acetic Acid, you are left with:
[A-] = 0.01 mol, as the OH has stripped the H+ off of 0.01 mol of the Acetic Acid.
[HA] = 0.02 mol, as this is the remaining concentration of Acetic Acid.
So, the equation should be:
Quote:
and not
Quote:
as it was listed in the slide.
Quote:
| pH = 4.76 + log (0.01 / 0.03) = 4.28 |
The equation is:
Quote:
| pH = pKa + log ( [A-]/[HA] ) |
Acetic Acid is the weak acid, so [HA] = 0.03 mol at the start of the rxn.
NaOH is the strong base, so [OH-] = 0.01 mol.
After NaOH reacts with the Acetic Acid, you are left with:
[A-] = 0.01 mol, as the OH has stripped the H+ off of 0.01 mol of the Acetic Acid.
[HA] = 0.02 mol, as this is the remaining concentration of Acetic Acid.
So, the equation should be:
Quote:
| pH = 4.76 + log (0.01 / 0.02) = 4.46 |
and not
Quote:
| pH = 4.76 + log (0.01 / 0.03) = 4.28 |
as it was listed in the slide.
MadDog5145
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Thank you, I was so preoccupied with thinking there was something with the logs that I forgot about basic chemistry. Doh.
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