1. Achuta!
Do Now… Finish gluing! HW… Read 8.2 #’s 3-7

2. = cations (+) = anions (-) Ions in Aqueous Solution Pb(NO3)2(s)
Pb(NO3)2(aq)
Pb2+(aq) NO31–(aq)
Pb2+
NO31–
Pb2+
NO31–
add
water
dissociation:
“splitting into ions”
NaI(s)
NaI(aq)
Na1+(aq) + I1–(aq)
add
water
Na1+
I1–
Na1+
I1–
= cations (+)
= anions (-)

3. = cations (+) = anions (-) NR
For double-replacement rxns(or precipitate rxns),
The reaction will
occur if any product is:
water a gas a precipitate
driving forces
Check new combinations to decide!
= cations (+)
= anions (-)
_ Pb(NO3)2(aq) + _ K2SO4(aq) 1 1 1
_ PbSO4(s) + _ KNO3(aq) 2
Pb2+
NO31–
K1+
SO42-
Pb2+
SO42-
(?)
K1+
NO31–
(?)
(ppt)
(aq)
_ FeCl3(aq) + _ Cu(NO3)2(aq) NR
Fe3+
NO31–
(?)
Cl1–
Cu2+
(?)
Fe3+
Cl1–
Cu2+
NO31–
(aq)
(aq)

4. = cations (+) = anions (-) precipitate: a solid product that forms
in an aqueous reaction
SPECTATOR
IONS
= cations (+)
= anions (-)
Na2CO3(aq) + Ca(NO3)2 (aq)
CaCO3(s) + 2NaNO3(aq)
2Na1+(aq) + CO32– (aq) + Ca2+(aq) + 2NO31–(aq)
COMPLETE IONIC
EQUATION
CaCO3(s) + 2Na1+ (aq) + 2NO31–(aq)
NET IONIC EQUATION
CO32– (aq) + Ca2+(aq) CaCO3(s)
clear
Na2CO3
solution
clear
Ca(NO3)2
solution
cloudy solution
containing CaCO3(s)
and NaNO3(aq)

5. Mix together ZnSO4(aq) and BaCl2(aq):
clear ZnSO4 solution
clear BaCl2 solution
ZnSO4 (aq)
BaCl2(aq)
Zn2+(aq) + SO42- (aq)
Ba2+(aq) Cl1–(aq)
Ba2+
Cl1–
Zn2+
SO42-

6. Mix them and get the complete ionic equation…
__Zn2+(aq) + __SO42–(aq) + __Ba2+(aq) + __Cl1–(aq) 1 1 1 2
yields
ppt
__BaSO4 (s) 1
+ __Zn2+(aq) + __Cl1-(aq) 1 2
Cl1–
Zn2+
Ba2+
SO42-
Cl1–
Cancel spectator ions to get net ionic equation…
__Ba2+(aq) + __SO42– aq) 1 1
__BaSO4(s) 1
Ba2+
SO42-
Ba2+
SO42-

7. = In a reaction: atoms are rearranged mass AND energy are conserved
charge
Balancing Chemical Equations
law of
conservation
of mass
same # of atoms
of each type on each
side of equation =

8. Reaction Conditions and Terminology
Certain symbols give important info about a reaction.
(s) = solid
(l) = liquid
(g) = gas
(aq) = aqueous
(dissolved in H2O)
NaCl(s)
NaCl(aq)
More on aqueous…
-- “soluble” or “in solution” also indicate that a
substance is dissolved in water (usually)

9. (i.e., clues about the reaction)
Other symbols…
(i.e., clues about the reaction)
means...
“yields” or “produces”
means ______ is added to the reaction
heat
MgCO3(s) MgO(s) + CO2(g)
Temp. at which we perform rxn. might be given.
400oC
C6H5Cl + NaOH C6H5OH + NaCl
The catalyst used might be given.
C2H4(g) + H2(g) C2H6(g) Pt

10. = cations (+) = anions (-) How do we know if a reaction will occur? LiNa Mg Al Zn Fe Pb H+ Cu Hg Ag Au
For single-replacement rxns, use Activity Series.
Elements above replace elements below.
= cations (+)
= anions (-)
_ Ca(s) + _ FeSO4 1 1 1
_ Fe (s) + _ CaSO4 (aq) 1
_ Pb(s) + _ Al2O3 (aq)
No Reaction
_ Cl2(g) + _ MgBr2(aq) 1 1
_ Br2 (g) + _ MgCl2 (aq) 1 1