1. pH P ractice Practice Problem # 1 © Mr. D. Scott; CHS If the hydrogen ion concentration of a solution is 2.5 x 10 -5 M, what is the pH of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pH = -log [H + ] Step 2 Substitute & solve. pH = -log [H + ] pH = -log (2.5 x 10 -5 ) pH = 4.602059 Step 3 Check sig-figs & round. pH = 4.60 Level 1

2. pH P ractice Practice Problem # 2 © Mr. D. Scott; CHS If the hydrogen ion concentration of a solution is 3.71 x 10 -8 M, what is the pOH of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pH = -log [H + ] pOH = pK w -pH Step 2 Substitute & solve. pH = -log [H + ] pH = -log (3.71 x 10 -8 ) pH = 7.4306 Step 3 Check sig-figs & round. pOH = 6.569 pOH = pK w -pH pOH = 14 – 7.4306 pOH = 6.5694 3 sig-figs Level 1

3. pH P ractice Practice Problem # 3 © Mr. D. Scott; CHS If a solution has [OH - ] = 4.7 x 10 -4 M, what is the pH of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pOH=-log[OH - ] pH = pK w -pOH Step 2 Substitute & solve. pOH = -log [OH - ] pOH = -log (4.7 x 10 -4 ) pOH = 3.3279 Step 3 Check sig-figs & round. pH = 10.67 pH = pK w -pOH pH = 14 – 3.3279 pH = 10.6721 2 sig-figs Level 1

4. pH P ractice Practice Problem # 4 © Mr. D. Scott; CHS If a solution has a pH of 3.75, what is the [OH - ] of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pOH = pK w -pH [OH - ]= 10 -pOH Step 2 Substitute & solve. pOH = pK w -pH pOH = 14 - 3.75 pOH = 10.25 Step 3 Check sig-figs & round. [OH - ] = 5.6 x 10 -11 M [OH - ] = 10 -pOH [OH - ] = 10 -10.25 [OH - ] = 5.623 x 10 -11 2 sig-figs Level 1

5. pH P ractice Practice Problem # 5 © Mr. D. Scott; CHS If a solution has a pOH of 11.49, what is the [H + ] of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH [OH - ]= 10 -pOH [H + ]=K w ÷[OH - ] Step 2 Substitute & solve. [OH - ] = 10 -pOH [OH - ] = 10 –11.49 [OH - ] = 3.236 x 10 -12 Step 3 Check sig-figs & round. [H + ] = 3.1 x 10 -3 M [H + ] = K w ÷[OH - ] [H + ] = 10 -14 ÷ 3.236 x 10 -12 [H + ] = 3.090 x 10 -3 2 sig-figs Level 1

6. pH P ractice Practice Problem # 6 © Mr. D. Scott; CHS If a solution has a [H + ] of 2.2 x 10 -1, what is the pOH of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH [OH - ]= K w ÷[H + ] pOH=-log[OH - ] Step 2 Substitute & solve. [OH - ] = K w ÷[H + ] [OH - ] = 10 -14 ÷ 2.2 x 10 -1 [OH - ] = 4.545 x 10 -14 Step 3 Check sig-figs & round. pOH = 13.34 pOH = -log[OH - ] pOH = -log(4.545 x 10 -14 ) pOH = 13.3424 2 sig-figs Level 1

7. pH P ractice Practice Problem # 7 © Mr. D. Scott; CHS If a solution has a [OH - ] of 8.4 x 10 -15, what is the pH of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pOH=-log[OH - ] pH = pK w -pOH Step 2 Substitute & solve. pOH = -log [OH - ] pOH =-log(8.4 x 10 -15 ) pOH = 14.0757 Step 3 Check sig-figs & round. pH = -0.076 pH = pK w -pOH pH = 14 – 14.0757 pH = -0.07572 2 sig-figs Level 1

8. pH P ractice Practice Problem # 8 © Mr. D. Scott; CHS If a solution has a pOH of 14.52, what is the [H + ] of the solution? Step 1 Identify the steps to be taken to solve. [H + ] [OH - ] pH pOH pH = pK w -pOH [H + ] = 10 -pH Step 2 Substitute & solve. pH = pK w - pOH pH = 14 – 14.52 pH = -0.52 Step 3 Check sig-figs & round. [H + ] = 3.3 M [H + ] = 10 -pH [H + ] = 10 -(-0.52) [H + ] = 3.311M 2 sig-figs Level 1