7. Consider a solution of formic acid (
HCHO
2
) and sodium formate (
NaCHO
2
), at pH=3.70. After the addition of 0.015 moles of
HNO
3
, the pH decreases by 0.12. What are the initial molarities of
HCHO
2
and
CHO
2
-
, if the
K
a
of
HCHO
2
is
1.8x10
-4
?
Challenge: Test yourself! Enter the answers below and if correct, jump into Section 14: Titration Curves. If you do not feel comfortable with buffers, you should try working through the question before working through the next series of questions, which is a guide through the solution.
Molarity of
HCHO
2
, Molarity of
CHO
2
-
: (Do
not
include units)
M ;
M