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### Topic: Titration Calculation w/ Sodium Acetate  (Read 29622 times)

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#### sundrops

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##### Titration Calculation w/ Sodium Acetate
« on: October 27, 2005, 12:25:35 AM »
I have a 10.00mL solution of 0.2000M CH3COONa is titrated with 0.1000M HCl to the equivalence point.
Write out the equation, calculate the volume HCl required and calculate the pH of the solution at its equivalence point.

Ok, I'm still learning this whole titration thing so bear with me guys, and let me know if I'm doing this right.

I'm not too sure about my Equation...

CH3COONa + H20 + HCl <-> H30+ + CH3COO- + NaCl
but what do i do with my NaCl? do i simply disregard it like I would with the water in my ICE table?

so i used M1V1=M2V2

so, (0.2M)(0.01L)=(0.1M)V2
V2 = 0.02L HCl

and to get my pH, I need my concentration of H+, so I can use pH=-log[H+], however I don't know my Ka value, nor do I know how much [H+] I have because I'm not sure about my equation so I cannot form my ice table either. I'm stuck.

Hopefully there's someone out there who understands titration equations.

#### mike

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #1 on: October 27, 2005, 12:29:58 AM »
Quote
CH3COONa + H20 + HCl <-> H30+ + CH3COO- + NaCl

CH3COONa + HCl ----> CH3COOH + NaCl
« Last Edit: October 27, 2005, 12:30:50 AM by mike »
There is no science without fancy, and no art without facts.

#### mike

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #2 on: October 27, 2005, 12:35:16 AM »
What is ICE table?

Your volume of 0.02L looks right.

Wouldn't the pH be 7 if it is a neutralisation?
There is no science without fancy, and no art without facts.

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #3 on: October 27, 2005, 12:38:23 AM »
thanks,

the reaction goes to completion? no equilibrium?
in that case is there a Ka value?

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #4 on: October 27, 2005, 12:39:22 AM »
how do you know that it is a neutrlization?

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #5 on: October 27, 2005, 12:42:35 AM »
is it because HCl is such a strong acid that the reaction goes to completion?

an ICE table is where you record the initial, the change, and finally the equilibrium concentrations of your products and reactants.

#### mike

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #6 on: October 27, 2005, 12:44:47 AM »
I would have thought it would go to completion, how did you measure the endpoint?
There is no science without fancy, and no art without facts.

#### mike

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #7 on: October 27, 2005, 12:57:43 AM »
Sorry I think you are right, at equivalence the solution will be slighly acidic.

pKa of actetic acid is about 4.76 I think
« Last Edit: October 27, 2005, 12:58:45 AM by mike »
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#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #8 on: October 27, 2005, 12:59:57 AM »
I haven't found the equivalence point yet, these are PRE-lab questions.   but in lab we will be using phenolpthalein.

so maybe the equivalence point being when 0.02L HCl has been used.

assuming that that is the case, how do I go about finding pH? I'm not given a pKa or a Ka value, or is there a may to determine the concentration of H+ produced? because I could just do the -log of [H+] and find pH that way...

any ideas?

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #9 on: October 27, 2005, 01:13:40 AM »
How do you know the pKa value?

so could I just go like this:

Ka = 10^(-pKa)
Ka = 1.78E-5

and then I really dont know what to do.
what do i do with the salt? how do i determine my pH?
I'm soooo lost.

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #10 on: October 27, 2005, 01:25:33 AM »
Please, can anyone help me find the pH of this solution?

I have no clue how to go about finding it...

#### mike

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #11 on: October 27, 2005, 01:29:30 AM »
I don't know how you can find it without knowing the pKa or the concetration of the final solution. Weak base strong acid titrations are more complicated than strong acid base titrations.

There is no science without fancy, and no art without facts.

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #12 on: October 27, 2005, 01:33:49 AM »
thx anyways...

I'll keep trying...

#### sundrops

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #13 on: October 27, 2005, 02:35:44 AM »

I can;t figure it out.... does anyone have any ideas on finding ph?

#### AWK

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##### Re:Titration Calculation w/ Sodium Acetate
« Reply #14 on: October 27, 2005, 02:39:35 AM »
Ka values you should find in physicochemical tables.
For calculation of the final pH treat the solution as pure diluted acetic acid.
Its concentarion is 0.06667 M (1/3 of staring comcentarion of sodium acetate)
AWK