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)