1. Chapter 9 Acids and Bases
Strengths of Acids and Bases
Making Dilutions
LecturePLUS Timberlake

2. Strengths of Acids and Bases
Strong acids completely ionize (100%) in aqueous solutions
HCl + H2O H3O+ + Cl- (100 % ions)
Strong bases completely (100%) dissociate into ions in aqueous solutions.
NaOH Na+ (aq) + OH-(aq)
(100 % ions)
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3. NH3, A Bronsted-Lowry Base
When NH3 reacts with water, most of the reactants remain dissolved as molecules, but a few NH3 reacts with water to form NH4+ and hydroxide ion.
NH H2O NH4+(aq) + OH- (aq)
acceptor donor
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4. Strong and Weak Acids and Bases
Strong acids
HCl, HNO3 , H2SO4
Most other acids are weak.
Strong bases
NaOH, KOH, and Ca(OH)2
Most other bases are weak.
LecturePLUS Timberlake

5. LecturePLUS Timberlake
Learning Check SW1
Identify each of the following as a
1) strong acid or base 2) weak acid
3) weak base
A. ___ HCl (aq)
B. ___ NH3(aq)
C. ___ NaOH (aq)
D. ___ H2CO3 (aq)
LecturePLUS Timberlake

6. LecturePLUS Timberlake
Solution SW1
Identify each of the following as a
1) strong acid or base 2) weak acid
3) weak base
A. _1__ HCl (aq)
B. _3__ NH3(aq)
C. _1__ NaOH (aq)
D. _2__ H2CO3 (aq)
LecturePLUS Timberlake

7. LecturePLUS Timberlake
Antacids
Used to neutralize stomach acid (HCl)
Many contain one or more weak bases
Alka-Seltzer: NaHCO3, citric acid, and aspirin
Di-gel: CaCO3 and Mg(OH)2
Gelusil: Al(OH)3 and Mg(OH)2
Maalox: Al(OH)3 and Mg(OH)2
Mylanta: Al(OH)3 and Mg(OH)2
LecturePLUS Timberlake

8. LecturePLUS Timberlake
More Antacids
Milk of Magnesia: Mg(OH)2
Rolaids: AlNa(OH)2CO3
aluminum sodium dihydroxy carbonate
Tums: CaCO3
Tempo: CaCO3, Al(OH)3, Mg(OH)2
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9. LecturePLUS Timberlake
Dilutions
Add water
Volume increases.
New concentration is less than initial
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10. Concentration of A Diluted Solution
A 25 mL sample of a 6.0 M KOH is diluted by adding 75 mL of water. Calculate the new concentration of the KOH solution.
Moles KOH = L x 6.0 moles = 0.15 moles
1 L
New volume = 25 mL + 75 mL = 100. mL = L
New molarity = moles = M
0.100 L
LecturePLUS Timberlake

11. LecturePLUS Timberlake
Learning Check SW 2
A 125 mL sample of a 3.0 M HCl is diluted by adding 250 mL of water. The new concentration of the HCl solution is
1) 8.0 M
2) 1.5 M
3) 1.0 M
LecturePLUS Timberlake

12. LecturePLUS Timberlake
Solution SW 2
3) 1.0 M
moles HCl = L x 3.0 moles = mole
1 L
new M = mole 1.0 M HCl
0.750 L
(new volume)
LecturePLUS Timberlake

13. LecturePLUS Timberlake
Learning Check SW 3
A 50.0 mL sample of 15% sucrose solution is diluted by adding 200. mL of water. The new concentration of the sucrose solution is
1) 3.0 %
2) 7.5 %
3) 10. %
LecturePLUS Timberlake

14. LecturePLUS Timberlake
Learning Check SW 3
A 50.0 mL sample of 15% sucrose solution is diluted by adding 200. mL of water. The new concentration of the sucrose solution is
1) 3.0 %
g sucrose = 50.0 mL x 15 g sucrose = 7.5 g
100 mL
new % = g sucrose = 3.0 % sucrose
250 mL
(new volume)
LecturePLUS Timberlake