1

EXCHANGEEXCHANGEGas-FormingGas-FormingReactionsReactions

REACTIONSREACTIONS

2

3

Gas Forming ReactionsGas Forming Reactions

4

EXCHANGEEXCHANGEAcid-BaseAcid-BaseReactionsReactions

REACTIONSREACTIONS

5

Solutions that conduct

electricity are called

ELECTROLYTESStrong

electrolytes dissociate completely

(or nearly so) into ions.

Aqueous Solutions

6Aqueous Solutions

Acids that ionize only to a small extent are called

weak electrolyte..

CH3CO2H(aq) ---> CH3CO2-(aq)

+ H+(aq)

7

Aqueous Aqueous SolutionsSolutions

Some compounds dissolve in water but do not conduct electricity.

They are called

nonelectrolytes.

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

8

Know the strong Know the strong acids & bases!acids & bases!

9

9

Strong AcidsANION

10

Base OH- in waterBase OH- in water

BASESBASES

NaOH(aq) ---> Na+(aq) + OH-(aq)

NaOH is a strong base

11

BASESBASESBASESBASES

CaO(s) + HCaO(s) + H22O(liq) O(liq) Ca(OH) Ca(OH)22(aq)(aq)

Metal oxides are basesMetal oxides are bases

CaO in water. Indicator shows solution is basic.

12

ACIDSACIDSACIDSACIDSNonmetal oxides can be acidsNonmetal oxides can be acids

COCO22(aq) + H(aq) + H22O(l) O(l) H H22COCO33(aq)(aq)

SOSO33(aq) + H(aq) + H22O(l) O(l) H H22SOSO44(aq)(aq)

and can come from burning coal and oil.and can come from burning coal and oil.

13

Acid-Base ReactionsAcid-Base Reactions

The “driving force” = water.The “driving force” = water.

Net ionic equationNet ionic equation

OHOH--(aq) + H(aq) + H++(aq) (aq) H H22O(l)O(l)

This applies to ALL reactions of This applies to ALL reactions of

STRONGSTRONG acids and bases. acids and bases.

14

EXCHANGEEXCHANGE:: Precipitation ReactionsPrecipitation Reactions

REACTIONSREACTIONS

15

IONIC COMPOUNDSCompounds in Aqueous Solution

Most redox reactions are in water — aqueous solutions - and involve ionic compounds

KMnO4 in water K+(aq) + MnO4-(aq)

16

Insoluble products: Precipitation formation

17

Precipitation ReactionsPrecipitation ReactionsPrecipitation ReactionsPrecipitation Reactions

The “driving force”= The “driving force”= solid.solid.

PbPb(NO(NO33))22(aq) + 2 K(aq) + 2 KII(aq) (aq) 2 KNO2 KNO33(aq) + (aq) + PbIPbI22(s)(s)

Net ionic equationNet ionic equation

PbPb2+2+(aq) + 2 (aq) + 2 II--(aq) (aq) PbIPbI22(s)(s)

18

If one ion from the If one ion from the “Soluble Compound” list is “Soluble Compound” list is present, the compound is present, the compound is

water soluble.water soluble.

Water Solubility of Ionic Compounds

19Net Net Ionic Ionic

EquatioEquationsns

Net Net Ionic Ionic

EquatioEquationsns

Mg(s) + 2 HCl(aq) Mg(s) + 2 HCl(aq) H H22(g) + MgCl(g) + MgCl22(aq)(aq)

We really should writeWe really should write

Mg(s) + 2 HMg(s) + 2 H++(aq) + 2 Cl(aq) + 2 Cl--(aq) (aq)

HH22(g) + Mg(g) + Mg2+2+(aq) + 2 Cl(aq) + 2 Cl--(aq)(aq)

The two ClThe two Cl-- ions are ions are SPECTATOR IONSSPECTATOR IONS — — they do not participate. Could have used NOthey do not participate. Could have used NO33

--..

20Net Ionic Net Ionic EquationsEquationsNet Ionic Net Ionic EquationsEquations

Mg(s) + 2 HCl(aq) Mg(s) + 2 HCl(aq) --> H--> H22(g) + MgCl(g) + MgCl22(aq)(aq)

Mg(s) + 2 HMg(s) + 2 H++(aq) + 2 Cl(aq) + 2 Cl--(aq) (aq) ---> H---> H22(g) + Mg(g) + Mg2+2+(aq) + 2 Cl(aq) + 2 Cl--(aq)(aq)

We leave the spectator ions out —We leave the spectator ions out —Mg(s) + 2 HMg(s) + 2 H++(aq) ---> H(aq) ---> H22(g) + Mg(g) + Mg2+2+(aq)(aq)

to give the NET IONIC EQUATIONNET IONIC EQUATION