1L of a buffer composed of acetic acid and sodium acetate has a pH of 4.3 (total molarity=0.0774) what is the capacity of 200mL of the buffer to survive an addition of HCl without changing by more than 0.4 pH units?
i am so lost please help!
i know you use the henderson hasselbach equation but i don't know what to do...
I would approach it this way but you go through the calculations. I will be using estimates and approximations.
4.3 = 4.74 log b/a
b/a = about 0.36 or
base = 0.36*acid
You have the molarity of 0.0774 and that tells you
acid + base = 0.0774.
This equation and the ratio above will allow you to calculate M acid (HAc) and base (Ac^-). After you know base and acid I would determine mols of each in 200 mL. The problem doesn't give a concn of HCl; I would assume they mean concn HCl which is 12M.
Next add 0.4 to the pH and calculate the ratio of acid to base. Subtract 0.4 from the pH and determine the ratio of acid to base. Using those numbers, make an ICE chart (two ICE charts--one for the + and one for the -) and use that to determine how much 12M HCl can be added.
If you have trouble, following these suggestions down to the ICE chart, show what you've done and I can help you through that last part. It's difficult to describe until you get there.