1. Acids, Bases, and Solutions

2. Solution A solution is a homogeneous mixture.
It is made by dissolving a solute in a solvent.
Solvent dissolves solute.
Water dissolves salt.
Water is the solvent, salt is the solute.

3. Concentration
A measurement of the amount of solute that is dissolved in a given solvent.
Solvent dissolves solute.
Ways of expressing concentration
Molarity (M) = moles solute / liters solution
Molality (m) = moles solute / kg solvent

4. Example
What is the molarity of a solution when 3 moles of NaOH are dissolved in 6 liters of solution?
Molarity = moles solute / liter sol’n
= 3 moles NaOH / 6 L sol’n
= 0.5 M NaOH
What is the molarity of a solution when 20 grams of NaOH are dissolved in 5 liters of solution?
20 grams NaOH = 0.5 moles
= 0.5 moles / 5 L sol’n
= 0.1 M NaOH

5. Now you try
What is the molarity of a solution created by adding 48 grams of lithium hydroxide to enough water to make 3 liters of solution?
Answer: M LiOH
What is the molarity of a solution created by adding 18 grams of hydrochloric acid to enough water to make 2 liters of solution?
Answer: M HCl

6. More
How many grams of potassium hydroxide are required to make 8 liters of a 0.3 M potassium hydroxide solution?
134.4 grams KOH
How many milliliters of a 1.2 M sulfuric acid solution can be made with 9.8 grams of sulfuric acid?
83.3 mL

7. More
How many grams of calcium hydroxide is in 95 milliliters of a 0.5 M calcium hydroxide solution?
3.515
How many liters of solution is needed to make a 0.1 M hydrobromic acid solution with 88 grams of hydrobromic acid?
10.9

8. More
What is the molality of a solution created by adding 58 grams of magnesium hydroxide to 4 liters of water?
Answer: m Mg(OH)2
What is the molality of a solution created by adding 49 grams of sulfuric acid to 3 liters of water?
Answer: m H2SO4

9. Calculating Ion Concentration
Write the dissociation equation.
Determine the concentration of the solution.
Use dimensional analysis and stoichiometry to determine ion concentration.
Example:
What is the hydrogen ion concentration if 2 moles of sulfuric acid are dissolved in 6 liters of solution?
H2SO4 → 2H+ + SO42-
2 moles H2SO4
2 moles H+
= 0.67 M [H+]
6 L sol’n
1 moles H2SO4

10. Now you try
What is the hydrogen ion concentration of a 3 liter solution with 24.5 grams of phosphoric acid?
0.25 M [H+]
What is the hydroxide ion concentration of a 5 liter solution with 7.4 grams of calcium hydroxide?
0.04 M [OH-]

11. You try
What is the hydrogen ion concentration of a 0.2 molar phosphoric acid solution?
Answer: 0.6 M [H+]
What is the hydroxide ion concentration of a solution made by adding 34 grams of calcium hydroxide to enough water to make 2 liters of solution?
0.5 M [OH-]

12. Acids and Bases Acids produce hydrogen ions when dissolved in water.
HCl → H+ + Cl-
Have a pH less than 7.
Bases produce hydroxide ions when dissolved in water.
Ca(OH)2 → Ca2+ + 2OH-
Have a pH greater than 7
Pure water is neutral with a pH of 7

13. pH scale
Scale used to show hydrogen ion concentration [H+] in a solution.
pH scale ranges from 0-14.
pH < 7 acidic
pH > 7 basic
pH = 7 neutral
pH = -log [H+]

14. You Try Calculate the pH of the following hydrogen ion concentrations.
0.01 M [H+]
0.006 M [H+]
0.4 M [H+]
M [H+]

15. More
Calculate the pH of a 250 mL solution with 7.3 grams of hydrochloric acid.
pH = 0.10
Calculate the pH of a 475 mL solution with 19.6 grams of sulfuric acid solution.
pH = 0.075
Calculate the pH of a 1.6 Liter solution with 49 grams of phosphoric acid.
pH = 0.028

16. pOH scale
Scale used to show hydroxide ion concentration [OH-] in a solution.
pOH scale ranges from 0-14.
pOH > 7 acidic
pOH < 7 basic
pOH = 7 neutral
pOH = -log [OH-]
pH + pOH = 14
[OH-] = 10-pOH
[H+] x [OH-] = 1 x 10-14

17. Practice
What is the pOH of a 5 Liter solution with 148 grams calcium hydroxide solution?
pOH = 0.10 basic
What is the pOH of a 375 mL solution with grams of aluminum hydroxide? Is this solution acidic or basic?
pOH = 2.50 basic
What is the pH of a 50 mL solution with grams of magnesium hydroxide? Is this solution acidic or basic?
pH = 10.9 basic