Monday, April 14, 20081. Chapter 17 Quiz

2. Notes Section 18.1 – Oxidation-Reduction

3. Homework – Reading Analysis – Section 18.1

Types of ReactionsTypes of Reactions

What were the types of reactions What were the types of reactions we talked about back in chapter 8?we talked about back in chapter 8?

PrecipitationPrecipitation Acid-baseAcid-base CombustionCombustion SynthesisSynthesis Decomposition Decomposition

Classify the reaction type Classify the reaction type for each of the following:for each of the following:

Forest fireForest fire Rusting steelRusting steel Gasoline in carGasoline in car Metabolism of foodMetabolism of food BatteriesBatteries

All of these are types of oxidation/reduction reactions.

OxidationOxidation

What do you think happens in these What do you think happens in these reactions? What does the word sound like?reactions? What does the word sound like?

Called oxidation because ‘O’ is added to Called oxidation because ‘O’ is added to elementelement

Originally used to describe combustion- Originally used to describe combustion- reaction of substances with oxygen in the reaction of substances with oxygen in the airair

When substances lost oxygen, they were When substances lost oxygen, they were reduced in mass reduced in mass called reduction called reduction reactionsreactions

Metal/Nonmetal Metal/Nonmetal ReactionsReactions

oo oo +1 -1+1 -1

2Na(s) + Cl2Na(s) + Cl22(g) (g) 2NaCl(s) 2NaCl(s)

Na Na e-e- Cl Cl NaNa++ClCl--

DrawingDrawing

Recall how we drew this transfer Recall how we drew this transfer of electrons.of electrons.

An electron is transferred from An electron is transferred from the sodium to the chlorinethe sodium to the chlorine

Oxidation-Reduction Oxidation-Reduction ReactionsReactions Reactions in which one or more Reactions in which one or more

electrons are transferredelectrons are transferred Also called Redox reactionsAlso called Redox reactions Oxidation is defined as the loss of Oxidation is defined as the loss of

electronselectrons Reduction is defined as the gain Reduction is defined as the gain

of electronsof electrons

Oxidation / ReductionOxidation / Reduction

OIL RIG – OIL RIG – OOxid. xid. IIs s LLoss, oss, RReduc. educ. IIs s GGainain

LEO the Lion goes GER – LEO the Lion goes GER –

LLose ose EElectrons lectrons OOxidationxidation

GGain ain EElectrons lectrons RReductioneduction

Oxidation / ReductionOxidation / Reduction

4Fe + 3O4Fe + 3O22 2Fe 2Fe22OO33

What is oxidized? What is reduced?What is oxidized? What is reduced?

Zn + ClZn + Cl22 Zn Zn2+2+ + 2Cl + 2Cl--

Practice Problem 18.1Practice Problem 18.1

2Cu + O2Cu + O22 2CuO 2CuO

2Cs + F2Cs + F22 2CsF 2CsF

Oxidation/ReductionOxidation/Reduction

Do metals gain or lose electrons?Do metals gain or lose electrons? Are they oxidized or reduced?Are they oxidized or reduced? Do some metals lose electrons more Do some metals lose electrons more

easily than others?easily than others? If you put Cu(s) in Mg(NOIf you put Cu(s) in Mg(NO33))22, will Cu , will Cu

lose e- and Mg gain them to become lose e- and Mg gain them to become Mg?Mg?– Which metal wants to get rid of e- more?Which metal wants to get rid of e- more?

Will a Reaction Occur?Will a Reaction Occur?

Magnesium wants to get rid of Magnesium wants to get rid of electrons more so it won’t take electrons more so it won’t take them away from copperthem away from copper

How do we know?How do we know? Electronegativities page 403Electronegativities page 403 Mg 1.2, Cu 1.9Mg 1.2, Cu 1.9 How about Mg and Fe(NOHow about Mg and Fe(NO33))22??