Asked by Molly B

If the Ka of a monoprotic weak acid is 4.5x10^-6 what is the pH of a .10M solution of this acid.

I don't even know how to start this problem, I'm totally lost please help!
Answered by DrBob222
Step 1. Write and balance the equation.
Step 2. Complete the ICE chart (initial, change. equilibrium).
Step 3. Write the Ka expression.
Step 4. Substitute the E line of the ICE chart into Ka expression and solve for the unknown.

.........HA ==> H^+ + A^-
I........0.1....0......0
C........-x.....x......x
E......0.1-x....x......x

Ka = (H^+)(A^-)/(HA)

4.5E-6 = (x)(x)/(0.1-x)
Solve for x = (H^+), then convert to pH.
Answered by Devin
ph=10.3
Answered by Molly B
The pH is not 10.3
Answered by Molly B
I got that the pH equals 2.67 is this number correct?
Answered by DrBob222
I don't get 2.67. If you will show your work I will find the error. I agree the answer isn't 10.3.
Answered by Cat
The correct pH is 3.17
Answered by DrBob222
3.17 is correct.
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