[sfgiants13]

You transferred 20. mL of acetic acid solution to an Erlenmeyer flask and added 2 drops of phenolphthalein solution. You filled your buret with 0.10 M NaOH so that the initial buret reading was 1.20 mL. After titrating your sample to the faint-pink phenolphthalein endpoint, the final buret reading was 16.95 mL.

a) How many moles of NaOH were delivered to the flask?

Moles of NaoH =  M x L = .10M  * .01575 L

b) What is the concentration of the acetic acid solution?

= .16 moles HAc/(.0020L) = 8.0 M

I submitted those and they are both wrong.  Where am I going wrong?

[sjb]

You transferred 20. mL of acetic acid solution to an Erlenmeyer flask and added 2 drops of phenolphthalein solution. You filled your buret with 0.10 M NaOH so that the initial buret reading was 1.20 mL. After titrating your sample to the faint-pink phenolphthalein endpoint, the final buret reading was 16.95 mL.

a) How many moles of NaOH were delivered to the flask?

Moles of NaoH =  M x L = .10M  * .01575 L

Maybe they needed this calculation actually worked out?

b) What is the concentration of the acetic acid solution?

= .16 moles HAc/(.0020L) = 8.0 M

I submitted those and they are both wrong.  Where am I going wrong?

Where have you got 0.16 mol of acetic acid from?
Can you write a balanced equation for your reaction?

[sfgiants13]

.16 moles NaOH *  1 mole HAc/1 mole NaOH = .16 moles HAc

It's a 1:1 of NaOH+HAc-----Ac+H20+Na

[sfgiants13]

Ok I think I might've done this wrong.  For the 1st part, is it 1.575 x 10^-3 mols, then just that divided by .02L to get that molarity?

[Borek]

is it 1.575 x 10^-3 mols, then just that divided by .02L to get that molarity?

Numbers look OK this time. Next thing to consider are significant numbers.

[sfgiants13]

Alright got it...thanks!  Don't know what I did the 1st time to screw up that bad but it's all good now.