Homework Help: chemistry

Posted by Anonymous on Sunday, November 2, 2008 at 12:13pm.

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.

chemistry - DrBob222, Sunday, November 2, 2008 at 12:39pm
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.
chemistry - Anonymous, Tuesday, November 4, 2008 at 3:20am
lol, mcmaster first year chem quiz...i bet you anything that he/she is in life/health science...

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