posted by Anonymous .
Hydrocyanic acid (HCN) is a much weaker acid than nitrous acid (HNO2). The pH values of 0.1 M solutions of the potassium salts of these two acids were determined separately. The statement which describes these determinations most accurately is:
a. ) Both solutions are acidic, with the HCN acid-derived solution the more acidic.
b. ) Both solutions are acidic, with the HNO2 acid-derived solution the more acidic.
c. ) Both solutions are neutral.
d. ) Both solutions are basic, with the HNO2 acid-derived solution the more basic.
e. ) Both solutions are basic, with the HCN acid-derived solution the more basic.
If you can't reason through to the answer, why not just work the problem and see what the pH is for the two solutions.
For example, for the HCN:
CN^- + HOH ==> HCN + OH^-
Kb = Kw/Ka = (HCN)(OH^-)/(CN^-)
Plug in the values for Kw, Ka, and (CN^-) and solve for (OH^-). (Remember HCN = Y and OH = Y so the numerator is just Y^2.
Do the same for KNO2.
Y^2/0.1 = 1 x 10^-14/4.9 x 10^-10. You need to look up the value for Ka for HCN and HNO2. I'm using an OLD set of tables.
lol, mcmaster first year chem quiz...i bet you anything that he/she is in life/health science...