# Chemistry

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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!

• Chemistry -

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.

• Chemistry -

ph=10.3

• Chemistry -

The pH is not 10.3

• Chemistry -

I got that the pH equals 2.67 is this number correct?

• Chemistry -

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.

• Chemistry -

The correct pH is 3.17

• Chemistry -

3.17 is correct.

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