# Warm-up Write a paragraph explaining how concentration of Warm-up Write a paragraph explaining how concentration of hydrogen ion and hydroxide ion effect pH. Give examples to support your explanation. What is pH? Acid Base [H+] = [OH-]

[H+] Acidic Basic Neutral pH = 7 [OH-]

Le Chateliers Principle [H3O+] [OH-] = 1 x10-14 Water: [H3O+] = [OH-] [H3O+] [OH-] = 1 x10-14 [H3O ] = 1 x10 M + -7

[OH-] = 1 x10-7 M Example 1: If the concentration of hydrogen ion in an unknown solution is 1 x10-13 M, what is the concentration of hydroxide? Example 2 [H3O+] = ? [OH-] = 1 x10-3 M

Is this substance acidic or basic? pH scale : measures acidity/basicity Sren Sorensen (1868 - 1939) ACID BASE

10x 10x10x 0 1 2 3 4

5 6 7 8 9

10 11 12 13 14 NEUTRAL 100x Each step on pH scale represents a factor of 10. pH 5 vs. pH 6 pH 3 vs. pH 5 pH 8 vs. pH 13

(10X more acidic) (100X different) (100,000X different) What is the formula for pH? pH = -log [H+] Acid Base [H+] = [OH-]

[H+] Acidic Basic Neutral pH = 7 [OH-]

Example 3 [H+] = 9.22 x10-8 M What is the pH of this substance? Example 4 [H+]= 5.39x10-8 M What is the pH of this substance? What about OH-? pOH = -log [OH-]

Acid Base [H+] = [OH-] [H+] Acidic Basic Neutral pH = 7

[OH-] Example 5 [OH- ] = 9.87 x10-3 M What is the pOH of this substance? Example 6 [OH- ]= 4.73x10-10 M What is the pOH of this substance?

How are pH and pOH related? pH + pOH = 14.00 pH = -log [H+] pOH = -log [OH-] Example 7 The pH of an unknown substance is 11.68. What is the pOH of this substance?

Example 8 The pOH of an unknown substance is 7.05. What is the pH of this substance? pH Calculations pH pH = -log[H3O+]

[H3O+] [H3O+] = 10-pH pH + pOH = 14 pOH [H3O+] [OH-] = 1 x10-14 pOH = -log[OH-]

[OH-] [OH-] = 10-pOH Challenge! What is the concentration of hydrogen ions in a solution with a pH of 6.96?