(multiple choice)Calculate the pH of the solution resulting from the addition of 10.0 mL of 0.10 M NaOH.?

Calculate the pH of the solution resulting from the addition of 10.0 mL of 0.10 M NaOH to 50.0 mL of 0.10 M HCN (Ka= 4.9 X 10^-10) solution.
a. 5.15
b. 8.71
c. 5.85
d. 9.91
e. 13.0

I did this problem about 3 times and keep getting 9.13. PLZZZ HELP

Answer:
That's a tricky one!

Part of the HCN has been neutralized so the new conc. of HCN is 0.0667 M. There has also been CN- ions put into solution as the salt NaCN the conc of CN- is 0.01667 M.
So putting these concs into the equation for Ka and solving for [H+] then taking logs I got a pH of 8.706.
Better check this!
d
I get 12.22 :S. If (for some strange reason, though my uni chem textbook has done this a couple of times) you assume that the addition of the NaOH doesnt affect the volume (once again, i can not see why, but i have seen it done) then i get 11.3. the only way to get an answer off that list is if u use 10mL as the volume :S. and that is for e) 13.0

does anybody else have any clue?

Bad question?

The answers post by the user, for information only, FunQA.com does not guarantee the right.



More Questions and Answers:
  • In Tie Dying how can you distinguish a homogeneous mixture from a homogeneous mixture?
  • Distilled water ??
  • Which of the following is true of a buffer prepared w/ equal concentrations of an acid and its conjugate base?
  • Why do we find gold as an element rather than as a compound?
  • Do all fuels produce carbon dioxide, water and energy when burnt or combusted?
  • Which of the following is NOT typical of most organic compounds?
  • Homework help! pls...?
  • Can someone help with this Chem problem?
  • Hi to all..,Can you give me an investigatory project?.., Plss...?