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Topic: Acetic Acid Titrant  (Read 9675 times)

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Offline FouRRaW

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Acetic Acid Titrant
« on: May 30, 2006, 10:37:54 PM »
Okay, so, we did a lab at school.  Using acetic acid (CH3OOH) as the titrant and NaOH as the concentration we tried to figure out.  I was just wondering if it's correct to write out this equation as the following since we need to figure out the products that are a result.


CH3OOH + NaOH =

So is this correct, can i use this as the equation (obviously I'd figure out the products from this)
Thank You

Offline mike

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Re: Acetic Acid Titrant
« Reply #1 on: May 30, 2006, 11:33:57 PM »
Yes
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Offline Will

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Re: Acetic Acid Titrant
« Reply #2 on: May 31, 2006, 10:59:39 AM »
Okay, so, we did a lab at school. Using acetic acid (CH3OOH) as the titrant and NaOH as the concentration we tried to figure out. I was just wondering if it's correct to write out this equation as the following since we need to figure out the products that are a result.

CH3OOH + NaOH =

So is this correct, can i use this as the equation (obviously I'd figure out the products from this)
Thank You
Yes

OMG mike! :o
Acetic acid is CH3COOH! ;)

Offline FouRRaW

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Re: Acetic Acid Titrant
« Reply #3 on: May 31, 2006, 10:18:57 PM »
Lol, sorry for forgetting the C in acetic acid.  Ya so a friend of mine told me that we don't need to include the Na part of the NaOH.
So then it would just be CH3COOH + OH  = CH3 COO- + H2O

Now i'm just wondering.. Question is ..

When a weak acid is titrated using a strong base as the titrant, the titrated mixture will be basic at the equivalence point. Based on the equation i put above, why is this true??

Attempt: My guess is that . the reaction won't go all the way to the way forward.  Cause it's not a strong acid on the reactants side, and the equilibrium is at the equivalence point. (So does a weak acid always mean it's on the basic side when confronted with a strong base?)

Thank You


Offline mike

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Re: Acetic Acid Titrant
« Reply #4 on: May 31, 2006, 10:39:18 PM »
Attention to detail, I like that ;-)

I think you can assume that the reaction is driven to completion by the strong base.
« Last Edit: May 31, 2006, 10:49:51 PM by mike »
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Offline utramos

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Re: Acetic Acid Titrant
« Reply #5 on: May 31, 2006, 10:49:33 PM »
CH3COOH + OH-  = CH3 COO- + H2O
Yes thats correct because thats the net ionic equation

For the reaction of a weak acid with a strong base, you must write the molecular formula of the acid rather than simply H+ because the dissociation of the acid in water is incomplete, Instead the acid exists primarily as athe neutral molecule.

Andrew Ramos

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College of Arts & Science
Inorganic Chemistry

Offline FouRRaW

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Re: Acetic Acid Titrant
« Reply #6 on: May 31, 2006, 11:06:42 PM »
Sorry, i'm still confused as to why it's Basic??
Like where did the surplus of OH- Ions come from?

Offline mike

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Re: Acetic Acid Titrant
« Reply #7 on: May 31, 2006, 11:08:54 PM »
Because at equivalence you would have neutralised all of the acid and only have OH- in solution = basic
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Offline FouRRaW

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Re: Acetic Acid Titrant
« Reply #8 on: May 31, 2006, 11:13:46 PM »
Wow, i must be stupid, didn't the reaction run to completion? And it's basic, is the H2O+
part basic??And why, if it is??
Thanks

Offline utramos

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Re: Acetic Acid Titrant
« Reply #9 on: May 31, 2006, 11:27:35 PM »
this is what i am assuming u had your burret full of NaOH probably a known concentration(strong base) and your sample of acetic acid Unknown concentration beneath with probably an indicator which turns pink when the concentration is nuetralized


Heres an example..
25ml sample of acetic acid is titrated and found to react with 94.7ml (amount being titrated) of .200m NaOH what is the molarity of the acid

NaOH + CH3COOH ----> CH3COONa + H20

(200 mol / L)(.0947 L )= .01894 mol of NaOH = .01894 CH3COOH

Molarity= .01894mol  = .758 m concentration of acid
              .0250 L


hopes this helps with what your trying to do...
A titration will all come to completion unless u do not add enough acid or base
Andrew Ramos

The University of Toledo
College of Arts & Science
Inorganic Chemistry

Offline FouRRaW

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Re: Acetic Acid Titrant
« Reply #10 on: May 31, 2006, 11:33:16 PM »
that's pretty much what our experiment was except that acetic acid was the titrant and the sodium hyrdroxide was the unknown concentration

Offline mike

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Re: Acetic Acid Titrant
« Reply #11 on: May 31, 2006, 11:45:40 PM »
Quote
Wow, i must be stupid, didn't the reaction run to completion? And it's basic, is the H2O+
part basic??And why, if it is??
Thanks

I am confused by this question.

Also if acetic acid was your titrant then what were you using for observation of end point? Colour change to indicate acid solution or just the disappearance of colour to signify basic solution completely neutralised?

One way or the other you are in essence neutralising the acid with base or base with acid to form a neutral solution and then the addition of the titrant will usually change the solution to either acid or basic (whichever is the opposite of what you started with). For example if your NaOH suddenly changes colour (with appropriate indicator) to signify it is now acidic then you know you have reached the end point.
There is no science without fancy, and no art without facts.

Offline FouRRaW

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Re: Acetic Acid Titrant
« Reply #12 on: May 31, 2006, 11:51:35 PM »
Ok that makes sense.  I think i can go from there.
thanks

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Re: Acetic Acid Titrant
« Reply #13 on: June 01, 2006, 03:13:21 AM »
I think you can assume that the reaction is driven to completion by the strong base.

You can't.

At the equivalence point you have a solution of salt of weak acid - which means you have a weak base (CH3COO-) in the solution. It will react with water making solution slightly basic.

Whether it means that reaction didn't proceed to the end or whether neutralization/hydrolyzis are separate process is a question on semantic, not on chemistry ;)
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Offline mike

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Re: Acetic Acid Titrant
« Reply #14 on: June 01, 2006, 03:30:34 AM »
So why is this not assuming the reaction has gone to completion? Surely the reaction must reach completion to become basic?

« Last Edit: June 01, 2006, 03:37:06 AM by mike »
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