Question
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!
I don't even know how to start this problem, I'm totally lost please help!
Answers
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.
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.
Devin
ph=10.3
Molly B
The pH is not 10.3
Molly B
I got that the pH equals 2.67 is this number correct?
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.
Cat
The correct pH is 3.17
DrBob222
3.17 is correct.