1. Strong Acid-Base Calculations
Acids & Bases
Lesson 6
Strong Acid-Base Calculations

2. Strong Acids & Bases Calculations

3. Strong Acids & Bases Calculations
When we consider strong acids and bases, remember this:
They ionize 100%
In other words, [strong acid] = [H3O+]
[strong base] = [OH-]
When you mix the acid with the base, consider which concentration of H3O+ or OH- is in excess.

4. Strong Acids & Bases Calculations
Part I: strong acid or strong base only in water Part II: Mixing the strong acid and the strong base together.

5. Part I: strong acid or strong base only in water

6. 1. Calculate the pH of 0.40 M HI.
HI  H+ + I-
0.40 M M M
pH = -Log[H+]
pH = -Log[0.40]
pH = 0.40

7. 2. Calculate the pH of 0.030 M Ba(OH)2.
Ba(OH)2  Ba2+ + 2OH-
0.030 M M M
pOH = -Log[OH-]
pOH = -Log[0.060]
pOH = 1.22
pH pOH =
pH =
pH =

8. Try: Calculate the pH of 0.020 M Mg(OH)2

9. 3. Calculate the pH of 100. 0 mL of 1. 0 M HCl after. 300. 0 mL of
3. Calculate the pH of mL of 1.0 M HCl after mL of water is added to it.
HCl  H+ + Cl- M
M M
pH = -Log[H+]
pH = -Log[0.25]
pH = 0.60

10. Try: Calculate the pH and pOH of 200. 0 mL of 2. 0 M HCl after 300
Try: Calculate the pH and pOH of mL of 2.0 M HCl after mL of water is added to it.

11. Part II: Mixing solutions of the strong acid and the strong base together.
Helpful hints:
Start as always by getting your [H3O+] And [OH-]
Hydronium ion and Hydroxide ion will neutralize each other, however if there is extra of one of the two…
Find the excess/extra you have.
If you have extra [OH-], your solution will be basic.
- If you have extra [H3O+], your solution will be acidic.

12. Example: 200. 0 mL of 0. 200 M HCl is mixed with 400. 0 mL of
Example: mL of M HCl is mixed with mL of M NaOH. Calculate the pH of the new solution.

13. TRY: calculate the final [H3O+], [OH-] and new pH in a solution formed when mL of 1.5 M HNO3 is added to 250.0mL of 0.80 M KOH

14. example How many moles of HCl(g) must be added to 40. 0mL of 0
example How many moles of HCl(g) must be added to 40.0mL of M NaOH to produce a solution having pH= , if it is assumed that there is no change in volume when the HCl is added?
p.143 example

16. TRY: How many moles of HCl(g) must be added to 30. 0mL of 0
TRY: How many moles of HCl(g) must be added to 30.0mL of M Ca(OH)2 to produce a solution having pH= , if it is assumed that there is no change in volume when the HCl is added?

17. Example: calculate the pH resulting from mixing 25. 0 mL of 0
Example: calculate the pH resulting from mixing 25.0 mL of M Ba(OH)2 with mL of M HCl.
Q60

19. TRY: calculate the pOH resulting from mixing 50. 0 mL of 0
TRY: calculate the pOH resulting from mixing 50.0 mL of M Sr(OH)2 with 35.0 mL of a solution containing g of HCl.

21. Ex: A chemist has 2. 000 L of 0. 00120 M KOH soltuion
Ex: A chemist has L of M KOH soltuion. What mass of HCl(g) would have to be added to the KOH solution to produce a solution having a pH of ? assume no change in volume occurs.

23. Homework:
p.143 #58, 59, 62, 63, 64, 66,67.