Chemistry
posted by Anya on .
determine the pH of a 0.116 M Ba(OH)2 solution at 25 degrees C.
i keep getting 13.06 for this answer, but the answer is 13.37 :S
what i do is i take the negative log of the concentration which is 0.9355 which is pOH.
i know that pH = 14  pOH
so i get pH = 13.06
where am i going wrong ? :S
thanks for help in advance!

haha I'm guessing your studying off the old chemistry multiple choice exam for tommorow's chemistry exam at ryerson?

You assumed barium hydroxide is totally dissociated. The solubility product constant is 5E3.

Anya, do you know how to do number 4 on the final chemistry exam. Please tell me.

i figured it out, i have to multiple the concentration by 2 because of the 2 hydroxides right?
and yes i do know # 4
you want to convert 0.0354 mg/mL at 1 atm to mol/L at 0.00036 atm.
so :
(0.0354 mg/mL) x ( 0.00036)
= 1.2744 x 10^5 mg*CO / mL
then you just want to convert units)
1.27 *10^5 mg*CO/mL is 1.27 * 10 ^5 g/L
multiply that by 1 mole CO/ 28 g
yyou get 4.5 * 10 ^ 7 
Yeah I see what you did. I did the same thing in a slightly different way and got 4.5X10^5. I see my mistake now
you have:
P1/C1=P2/C2

P1=1 C1=0.0354
P2=0.00036 C2?

1/0.0354=0.00036/C2
then you cross multiplied and then converted the value 1.27X10^5 from grams to mols.
================================
Do you know how to do 6 can you tell me?