Determining if a compound is soluble (aq) or NOT

• LOOK AT TABLE F

– LiOH– Cu(NO3)2 – AgCl2– MgS– NaS2

– KOH

– aq– aq – insoluble = precipitate = s– insoluble = precipitate = s– aq– aq

Double Replacement Reactions

Double Replacement

Format: AX + BY AY + BX

DR rns occur in aqueous solutions

• So, what exactly happens to a substance when we put it in water? – depends if ionic or covalent

Dissolving

• sugar molecules spread out among water molecules

Covalent substance – ex: sugar (C6H12O6)C6H12O6(s)

C6H12O6(aq)

Dissolving• Ionic substance – • ex: table salt (NaCl)

• NaCl(s) Na+1(aq) + Cl-1(aq)

•ions spread out among water molecules

Double Replacement Reactionsoccur with 2 ionic compound

solutions• Products can be:

- liquid (H2O)- - gas- - solid

Reactions producing solids

Precipitation: solid is formed - opposite of dissolving! MOVIE

EX: Reactions producing Solids

2 NaOH(aq) + CuCl2(aq)

2 NaCl(aq) + Cu(OH)2(s)

This is the Chemical Equation but it’s not This is the Chemical Equation but it’s not the whole story…the whole story…

In solution it’s not NaOH and CuCl2You actually have ions floating around

in water

• Reactants: 2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq)

• Products: 2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s)

ions in solution are written as aqueous

OH H

Na+1

Cu2+

OH H

OH H

OH H

OH H

Cu2+

Cu2+

Cu2+

Na+1

Na+1

Cl+1

Cl-1

Cl+1

H O

H O

H O

2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s)

Cu

HO

H O

Cu

HO

Net Ionic Equations2Na+1(aq) + 2OH-1(aq) + Cu2+(aq) + 2Cl-1(aq)

2Na+1(aq) + 2Cl-1(aq) + Cu(OH)2(s)

•Notice some ions do not participate in reaction • = spectator ions • cross out spectator ions to get net ionic equation

Here’s what is really involved in the reaction…

2OH-1(aq) + Cu2+(aq) Cu(OH)2(s)

2 NaOH(aq) + CuCl2(aq) 2 NaCl(aq) + Cu(OH)2(s)

Double Replacement Reactionsoccur with 2 ionic compound

solutions• Products can be:

- liquid (H2O)- - gas- - solid

Reactions that form WaterHBr(aq) + NaOH(aq) H2O(l) + NaBr(aq)

H+1(aq) + Br-1(aq) + Na+1(aq) + OH-1(aq)

H2O(l) + Na+1(aq) + Br-1(aq)

H+1(aq) + OH-1(aq) H2O(l)

Reactions that form Gases

HCl(aq) + NaHCO3(aq) H2CO3(aq) + NaCl(aq)

H2O(l) + CO2(g)

Reactions that form Gases

HCl(aq) + NaHCOHCl(aq) + NaHCO33(aq) (aq)

HH22O(l) + COO(l) + CO22(g) + NaCl(aq)(g) + NaCl(aq)

H+1(aq) + Cl-1(aq) + Na+1(aq) + HCO3-1(aq)

H2O(l) + CO2(g) + Na+1(aq) + Cl-1(aq)

HH+1+1(aq) + HCO(aq) + HCO33-1-1(aq) (aq) H H22O(l) + COO(l) + CO22(g)(g)

Conservation of Charge

total charge (reactant side) must equaltotal charge on product side

• 2OH-1(aq) + Cu2+(aq) Cu(OH)2(s)• -1 x 2 + +2 = 0

• H+1(aq) + OH-1(aq) H2O(l)

• HH+1+1(aq) + HCO(aq) + HCO33-1-1(aq) (aq) H H22O(l) + COO(l) + CO22(g)(g)