Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: zeshkani on October 02, 2006, 10:06:49 PM
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i have very quick question.
What would be the titration error if you used phenolphthalein as the indicator for the titration of a 25.00 mL solution of 0.08943 M ammonia with 0.1000 M HCl?
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Huge. Show us what you think and we will tell you why.
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here
.08943M* .025L / .1 * 1000 = 22.357mL
THEN
.08943-x =x2
x= square root of the Kb(1.8e-5)*.08943
x=1.6e-6
-log(1.6e-6)
=5.79 pOH
= 14-5.79
=8.21 pH
then from here i dont know where to go ?
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You must describe what you are doing. I can help, but I don't want to waste my time guessing what you did and why.
here
.08943M* .025L / .1 * 1000 = 22.357mL
THEN
.08943-x =x2
Are these two connected in some way, or just thrown at random?
8.21 pH
If I guess correctly what you trying to do - you are wrong.
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well dont we have to multiply the [.08943] by the (.025L) then divide by .1 then multiply by 1000ml = to give the amount of ml need to reach the equ.pt. which cam out to be 22.357
then
do the
Initial = .08943 0 0
Equ = .08943-x x x
x2= Kb of ammonia * .08943M
x = square root of Kb * .08943M
which gives us the [OH] CONCENTRATION
take the -log(of the[OH]
which is the pOH ?
then just take 14- pOH
which gives pH
and from here on iam trying to do this but i dont know if iam right or wrong
([OH] - .08943M) - .08943 / ([OH]-.08943)*100 = .001789% ???
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well dont we have to multiply the [.08943] by the (.025L) then divide by .1 then multiply by 1000ml = to give the amount of ml need to reach the equ.pt. which cam out to be 22.357
Are you using it in further calculations, or have you calculated it just to calculate it?
Initial = .08943 0 0
Equ = .08943-x x x
x2= Kb of ammonia * .08943M
x = square root of Kb * .08943M
which gives us the [OH] CONCENTRATION
take the -log(of the[OH]
which is the pOH ?
then just take 14- pOH
which gives pH
and from here on iam trying to do this but i dont know if iam right or wrong
([OH] - .08943M) - .08943 / ([OH]-.08943)*100 = .001789% ???
You are calculating some pH. pH of what? What for?
What is definition of titration error?