Transcript Synthesis and Decomposition Reactions

Gas Tests
Gas
Test
Positive
O2
glowing splint
reignites
H2
burning splint
pops
CO2
limewater
cloudy
Synthesis and Decomposition
Reactions
Diatomic Elements:
H2 (g)
N2 (g)
O2 (g)
Polyatomic Elements:
P4 (s) and S8 (s)
Use Phase symbols
(s) (l)
(g) (aq)
F2 (g)
Cl2 (g)
Br2 (l)
I2(s)
Synthesis means to combine.
Elements combine to form compounds.
A + B  AB
S8 (s)
6 Li (s) +
+ 8 O2 (g)  8 SO2 (g)
N2 (g) 
2 Li3N (s)
Ionic compounds are solid
Decomposition means to break down.
Compounds break down into elements which requires energy that
comes from heating or electrolysis.
Electrolysis uses inert electrodes and an electric current through a
molten or aqueous solution.
heat
AB

2 HgO (s)
∆

A + B
2 Hg(l)
+
O2(g)
electrolysis
2 H2O(l)
 2 H2 (g)
+
O2 (g)
Molten table salt is electrolyzed to produce molten sodium and another
gas.
∆
2 NaCl (l)  2 Na (l)
+ Cl2 (g)
Nitrogen from the air reacts with oxygen to produce gaseous nitrogen
dioxide.
N2 (g) +
2 O2 (g)
 2 NO2 (g)
A sample of Copper II oxide is heated.
2 CuO(s)  2 Cu (s)
+ O2 (g)
A silver spoon tarnishes when exposed to sulfur.
16 Ag (s) + S8 (s)
Reaction Song
 8 Ag2S (s)