Tuesday, April 30th: “A” DayWednesday, May 1st: “B” Day

AgendaHomework questions/collectFinish section 15.2Section 15.2 workday:

Practice pg. 545: 1,2,4Sec. 15.2 review, pg. 547: #1-12Concept Review: “Acidity, Basicity, and pH”Quiz over section 15.2 next time…

Measuring pH

We know how to calculate the pH from the [H3O+] or [OH-], but can we calculate the [H3O+] or [OH-], if we know the pH?

You bet your buttons we can!

Measuring pH

The pH equation may be rearranged to calculate the hydronium ion (H3O+) concentration from the pH.

[H3O+] = 10−pH

Sample Problem C, pg. 545Calculating [H3O+] and [OH-] from pH

What are the concentrations of the hydronium and hydroxide ions in a sample of rain water that has a pH of 5.05?

[H3O+] = 10−pH

[H3O+] = 10-5.05

[H3O+] = 8.91 X 10-6 MKw = [H3O+] [OH-] = 1.00 X 10-14

(8.91 X 10-6 M) [OH-] = 1.00 X 10-14

[OH-] = 1.12 X 10-9 M(3 sig figs)

Additional ExampleIf the pH of a solution is 8.1, what is [H3O+] in the

solution? What is the [OH-] in the solution?[H3O+] = 10−pH

[H3O+] = 10 –8.1

[H3O+] = 7.9 X 10-9 MKw = [H3O+] [OH-] = 1.00 X 10-14

(7.9 X 10 -9) [OH-] = 1.00 X 10-14

[OH-] = 1.3 X 10-6 M(2 sig figs)

Section 15.2 Workday

Practice pg. 545: #1,2,4Section 15.2 review: Pg. 547: #1-12Section 15.2 concept review: “Acidity, Basicity,

and pH”

Quiz over section 15.2 next time…