Chemistry SM-1232 Week 7 Lesson 1

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.