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Chapter 9 Acids and Bases. Strengths of Acids and Bases Making Dilutions. Strengths of Acids and Bases. Strong acids completely ionize (100%) in aqueous solutions HCl + H 2 O H 3 O + + Cl - (100 % ions )
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Chapter 9Acids and Bases Strengths of Acids and Bases Making Dilutions LecturePLUS Timberlake
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) LecturePLUS Timberlake
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. NH3 + H2O NH4+(aq) + OH- (aq) acceptor donor + + LecturePLUS Timberlake
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
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
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
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)3and Mg(OH)2 Maalox: Al(OH)3and Mg(OH)2 Mylanta: Al(OH)3 and Mg(OH)2 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 LecturePLUS Timberlake
Dilutions • Add water • Volume increases. • New concentration is less than initial LecturePLUS Timberlake
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 = 0.025 L x 6.0 moles = 0.15 moles 1 L New volume = 25 mL + 75 mL = 100. mL = 0.100 L New molarity = 0.15 moles = 1.5 M 0.100 L 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
Solution SW 2 3) 1.0 M moles HCl = 0.250 L x 3.0 moles = 0.75 mole 1 L new M = 0.75 mole 1.0 M HCl 0.750 L (new volume) 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
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 % = 7.5 g sucrose = 3.0 % sucrose 250 mL (new volume) LecturePLUS Timberlake