Presentation is loading. Please wait.

Presentation is loading. Please wait.


Similar presentations

Presentation on theme: "ACIDS AND BASES"— Presentation transcript:


2 Section 18.1 Introduction to Acids and Bases
Identify the physical and chemical properties of acids and bases. Classify solutions as acidic, basic, or neutral. Compare the Arrhenius and Brønsted-Lowry models of acids and bases. Different models help describe the behavior of acids and bases. Section 18-1

3 Some common acids: Sulfuric acid, H2SO4 Hydrochloric acid, HCl
Nitric acid, HNO3 Carbonic acid, H2CO3 Phosphoric acid, H3PO4 Acetic acid, HC2H3O2

4 Some common bases: Sodium hydroxide, NaOH Calcium hydroxide, Ca(OH)2
Potassium hydroxide, KOH Magnesium hydroxide,Mg(OH)2 Aluminum hydroxide, Al(OH)3 Ammonia, NH3

5 The Arrhenius Model The Arrhenius model states that an acid is a substance that contains hydrogen and ionizes to produce hydrogen ions in aqueous solution, and a base is a substance that contains a hydroxide group and dissociates to produce a hydroxide ion in solution. Section 18-1

6 The Arrhenius Model (cont.)
Arrhenius acids and bases HCl ionizes to produce H+ ions. HCl(g) → H+(aq) + Cl–(aq) NaOH dissociates to produce OH– ions. NaOH(s) → Na+(aq) + OH–(aq) Some solutions produce hydroxide ions even though they do not contain a hydroxide group. Section 18-1

7 Properties of Acids and Bases (cont.)
The usual solvent for acids and bases is water—water produces equal numbers of hydrogen and hydroxide ions in a process called self-ionization. H2O(l) + H2O(l) ↔ H3O+(aq) + OH–(aq) The hydronium ion is H3O+. Section 18-1

8 Properties of Acids and Bases (cont.)
All water solutions contain hydrogen ions (H+) and hydroxide ions (OH–). An acidic solution contains more hydrogen ions than hydroxide ions. A basic solution contains more hydroxide ions than hydrogen ions. Section 18-1

9 The Brønsted-Lowry Model
The Brønsted-Lowry Model of acids and bases states that an acid is a hydrogen ion donor, and a base is a hydrogen ion acceptor. The Brønsted-Lowry Model is a more inclusive model of acids and bases. Section 18-1

10 The Brønsted-Lowry Model (cont.)
A conjugate acid is the species produced when a base accepts a hydrogen ion. A conjugate base is the species produced when an acid donates a hydrogen ion. A conjugate acid-base pair consists of two substances related to each other by donating and accepting a single hydrogen ion. Section 18-1

11 The Brønsted-Lowry Model (cont.)
Hydrogen fluoride—a Brønsted-Lowry acid HF(aq) + H2O(l) ↔ H3O+(aq) + F–(aq) HF = acid, H2O = base, H3O+ = conjugate acid, F– = conjugate base Section 18-1

12 The Brønsted-Lowry Model (cont.)
Ammonia— Brønsted-Lowry base NH3(aq) + H2O(l) ↔ NH4+(aq) + OH–(aq) NH3 = base, H2O(l) = acid, NH4+ = conjugate acid, OH– = conjugate base Substances that can act as acids or bases are called amphoteric. Section 18-1

13 Water is amphoteric: HCl + H2O  H3O+ + Cl-1 NH3 + H2O  NH4+1 + OH-
Acts as both an acid and a base Water is amphoteric: HCl + H2O  H3O+ + Cl-1 Proton acceptor NH3 + H2O  NH OH- Proton donor



16 Monoprotic and Polyprotic Acids
An acid that can donate only one hydrogen ion is a monoprotic acid. Only ionizable hydrogen atoms can be donated. Section 18-1

17 Monoprotic and Polyprotic Acids (cont.)
Acids that can donate more than one hydrogen ion are polyprotic acids. Section 18-1

18 Properties of Acids Acids are proton (hydrogen ion, H+) donors
Acids have a pH lower than 7 Acids taste sour Acids effect indicators Blue litmus turns red Methyl orange turns red Acids react with active metals, producing H2 Acids react with carbonates Acids neutralize bases

19 Acids Effect Indicators
Blue litmus paper turns red in contact with an acid. Methyl orange turns red with addition of an acid

20 Acids React with Active Metals
Acids react with active metals to form salts and hydrogen gas. Mg + 2HCl  MgCl2 + H2(g) Zn + 2HCl  ZnCl2 + H2(g) Mg + H2SO4  MgSO4 + H2(g)

21 Acids React with Carbonates
2HC2H3O2 + Na2CO3 2 NaC2H3O2 + H2O + CO2

22 Effects of Acid Rain on Marble (calcium carbonate)
George Washington: BEFORE George Washington: AFTER

23 Properties of Bases Bases are proton (hydrogen ion, H+) acceptors
Bases have a pH greater than 7 Bases taste bitter Bases effect indicators Red litmus turns blue Phenolphthalein turns purple Solutions of bases feel slippery Bases neutralize acids

24 Bases Effect Indicators
Red litmus paper turns blue in contact with a base. Phenolphthalein turns bright pink in a base.

25 A B C D Section 18.1 Assessment A conjugate acid is formed when:
A. a base accepts a hydrogen ion B. an acid accepts a hydrogen ion C. an acid donates a hydrogen ion D. a base donates a hydrogen ion A B C D Section 18-1

Download ppt "ACIDS AND BASES"

Similar presentations

Ads by Google