Chemistry SM-1232Week 7 Lesson 1

Dr. Jesse ReichAssistant Professor of Chemistry

Massachusetts Maritime AcademyFall 2008

Class Today• YES class on Friday• Chapter 13 HW due, quiz due• Today Chapter 14: Acids and Bases

Acids

• Properties include:• Sour taste• Dissolve many metals• Turn litmus paper red• Can have strong smells

Typical Acids

• Sulfuric Acid• Nitric Acid • Acetic Acid• Carboxylic acids• Citric Acid• Malic Acid• Hydrochloric Acid• What’s common to all acid names?

Bases

• Properties:• Bitter taste• Feel slippery• Turn litmus paper blue• Some have strong smells

Typical Bases

• Sodium hydroxide• Potassium hydroxide• Magnesium hydroxide• Sodium bicarbonate• Sodium sulfate• Lithium phosphate• (ammonia)• What are common pieces to base names?

Acid and Base Definitions

• 1: Arrhenius Definition• Acid: produces H+ ions in aqueous solutions,

also just called protons• Base: produces OH- ions in aqueous solutions

Arrhenius acid

• HCl H+ + Cl-• H2SO4 2H+ + SO4

2-

• H3PO4 3H+ + PO43-

Hydronium ion

• H+ when in water reacts with water to make an hydronium ion

• H+ + H2O H3O+

Arrhenius Base

• A compound that produces OH- ions when dissolved in water.

• NaOH Na+ + OH-

• Mg(OH)2 Mg2+ + 2OH-

Typical Bases

• NaOH, sodium hydroxide• KOH, potassium hydroxide• NaOCH3, Soidum methoxide• Calcium Carbonate

Bronsted-Lowry Definition

• This definition rests on the transfer of H+ ions.• Bronsted acid is a proton H+ donor• Bronsted base is a proton H+ acceptor

Acid Example

• HCl + H2O H3O+ + Cl-

• H2SO4 +2 H2O 2H3O+ + SO42-

Base

• NH3 + H2O NH4+ + OH-

• NaOH Na+ + OH-

Amphoteric

• Water is amphoteric because it can act like an acid or base.

• HCl + H2O H3O+ + Cl-

• NH3 + H2O NH4+ OH-

Conjugate Acid-Base Pairs

• NH3 + H2O NH4+ + OH-

• Base, acid conjugate acid, conjugate base

• On the left NH3 gained it’s a base

• H2O gave H+ it’s a base

• On the right, now NH4+ has an H+ to give so it’s

the conjugate acid• OH- lost the H+ so now it’s the conjugate base

Acid Base Reactions

• Neutralization• Acid Reactions• Base Reactions

Neutralization

• Most common reaction!• For Arrhenius acid Base Reactions:• Acid + Base = Water + Salt

• For Bronstead acid base reactions:• AcidH+ + Base- conjugate base- + conjugate acid+

Arrhenius Acid base Reactions

• HCl + NaOH H2O + NaCl

• H2SO4 + 2 KOH 2 H2O + K2SO4

• Label the acid, base, salt and water

Bronstead Acid-Base Reactions

• HCl + NH3 NH4+ + Cl-

• Label the acid, base, conjugate acid, and conjugate base

Fancy Neutralization

• HCl + NaHCO3 H2CO3 + NaCl

• H2CO3 H2O + CO2

Acid Reactions

• Acids eat metals• 2HCl + Mg H2 + MgCl2

• H2SO4 + Zn H2 + ZnSO4

• 2HCl + Fe H2 + FeCl2

Acids eat oxides

• 2HCl + K2O 2 KCl + H2O• 2HBr + MgO H2O + MgBr2

Base Reactions

• Bases dissolve a few metals• 2 NaOH + 2Al + 6H2O 2NaAl(OH)4 + 3 H2

Work over break

• 14.4-14.7 copy example problems. They are a pain. They will take time. Plan for it. Be sure to read in chapter 14 up through page 509.