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Chapter 19 Acids and Bases.

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Presentation on theme: "Chapter 19 Acids and Bases."— Presentation transcript:

1 Chapter 19 Acids and Bases

2 TEKS (G) define acids and bases and distinguish between Arrhenius and Bronsted-Lowry definitions and predict products in acid base reactions that form water; (H) understand and differentiate among acid-base reactions, precipitation reactions, and oxidation-reduction reactions; (I) define pH and use the hydrogen or hydroxide ion concentrations to calculate the pH of a solution; and

3 Properties of Acids and Bases
Tastes sour reacts with metals to produce hydrogen gas Reacts with carbonates to produce carbon dioxide conducts electricity so are good electrolytes Turns blue litmus red Has a pH between 0-6 Reacts with a base to produce salt and water Tastes bitter Slippery conducts electricity Turns red litmus blue Reacts with an acid to produce salt and water Has a pH above 7

4 Ions in Solution contains more H+ ions than OH- ions H+ > OH-
Acidic Solution Neutral solutions Basic Solution contains more H+ ions than OH- ions H+ > OH- neither acidic or basic equal # of H+ and OH- ions H+ = OH- contains more OH- ions than H+ ions H+ < OH-

5 Arrhenius vs Bronstead-Lowry
an acid is a substance that ionizes to produce hydrogen ions in aqueous solution States that an acid is a hydrogen-ion donor a base dissociates to produce a hydroxide ion in aqueous solution a base is a hydrogen-ion acceptor

6 Amphoteric Substances
Amphoteric- a substance that can act as both acids and bases Ex: Water When HF dissolves in water, water acts as base When NH3 dissolves in water, water acts as acid

7 Strong Acids vs Weak Acids

8 19.2 Strengths of Acids Strong Acids Weak Acids
acid that ionizes completely acid that ionizes only partially in dilute aqueous solutions Ex: HC2H3O2, H2CO3 Good conductors of electricity, makes great electrolytes Ex: HCl, HNO3, H2SO4 Poor conductors of electricity Reactions shown with  Reactions shown with >

9 Strong Base vs Weak Base

10 19.2 Strengths of Bases Strong Base Weak Base
dissociate completely into metal ions and hydroxide ions Ex: NaOH, Ca(OH)2 ionizes only partially in dilute aqueous solutions to form conjugate acid of the base and hydroxide ion Ex: CH3NH2

11 19.3 What is pH? Pure water contains equal numbers of H+ and OH- ions
Kw = [H+] [OH-] Use 1.0x10-14 M for Kw

12 Ion Product Constant of Water
Ion Product Constant of Water- Kw- the value of the equilibrium constant for water At 298 K, Kw is 1.0 x 10-14 Kw = [H+] [OH-]

13 pH pH- the negative logarithm of the hydrogen ion concentration
pH = -log [H+]

14 Math Calculations pH + pOH = 14 pH= -log(H+)
pH when given pOH = 14- (-log OH)

15 pH Scale pH below 7 is an acid pH above 7 is a base pH = 7 is neutral

16 pH of Common Substances
Timberlake, Chemistry 7th Edition, page 335


18 pH Scale

19 19.4 Neutralization Neutralization Reaction- acid & base react to produce a salt & water a Double-Replacement Reaction Salt- an ionic compound formed from the cation of a base & anion of an acid

20 Acid-Base Indicator- a compound that changes color as it is placed in either an acid or base


22 Titration The process in which an acid-base neutralization reaction is used to determine the concentration of a solution of unknown concentration.

23 End Point The point at which an indicator used in a titration changes color

24 Buffers A solution that resists changes in pH when limited amounts of acids and bases are added.

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