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Topic: how to use ICE table properly?  (Read 6377 times)

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Offline m0on

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how to use ICE table properly?
« on: October 01, 2009, 01:29:58 AM »
we have this lab for Ka of ethanoic acid (vinegar) and im really confused about the reaction and ICE table

we did titration NaOH with ethanoic acid and found the pH graph using CBL units

then the teacher gave us this reaction to use in ICE table:

CH3COOH > H + CH3COO

but y isnt it CH3COOH + NaOH > watever comes here

anyways, when i make ICE, i calculated the initial moles of ethanoic acid, and for H and CH3COO they'll be 0 (thats wat the teacher said).
 
1-but i dont know how to calculate the change of moles for all of them.

2-i also dont know what this step (4b) says: Using the initial pH recorded, calculate the hydronium ion concentration of
the ethanoic acid solution. (whcih pH shoud i use?)

this is what i got so far

          CH3COOH                 H            CH3COO
I           .98                        0                0

C

E

for a link of the lab procedure.. here it is:
http://www.stemnet.nf.ca/courses/chem3202/unit02_org03_ilo07/c3_lab_04.pdf

and the step 4B, i odnt get it


help me please

Offline Borek

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Re: how to use ICE table properly?
« Reply #1 on: October 01, 2009, 03:38:43 AM »
but y isnt it CH3COOH + NaOH > watever comes here

Because you use ICE table to calculate pH of pure caetic acid BEFORE the titration, that is, before NaOH was added.

Quote
1-but i dont know how to calculate the change of moles for all of them.

From simple stoichiometry - for example, if x moles of H+ appear, exactly x moles of acetic acid dissociated.
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