4
Chemical Physical Changes
Chemistry is the study of changes in matter- the stuff around us.
Change can be physical or chemical.
Demo- water wine milk beer
Physical Change
Nothing new is produced.
Change of state
(s)
(l)
(g)
(aq)
NH4NO3 dissolves in water- Demo
Energy + NH4NO3(s)

NH4+(aq) +
NO3-(aq)
Do not add water- not a reaction with water.
This reaction is endothermic because it gets cold or absorbs energy.
Energy is on the left
Chemical Change
Something new is produced
New formulas
New properties
Colour changes
Bubbles
Precipitates- solids form in solution
Solids react away
Nitrogen triiodide explodes
2 NI3(s)

N2(g)
Exothermic
Produces energy
Energy is on the right
+ 3 I2(g) +
energy
Classify as Chemical or physical Change
Gasoline evaporating
physical
Gasoline burning
chemical
Fog condensing
physical
Iron rusting
chemical
Classify as Chemical or physical Change
Cooking an egg
chemical
Digesting an egg
chemical
H2O(g)
 H2O(l) + energy
2H2O + energy  2H2(g) + O2(g)
physical
chemical
Classify as Chemical or Physical Property
Solution colour
physical
Flammability
chemical
Density
physical
Reactivity
chemical
Changes in Physical State
Solid
freezing
sublimation
Liquid
Gas
condensation
Changes in Physical State
Solid
melting
condensation or sublimation
Liquid
Gas
evaporation
Using Melting and Boiling Points to Predict State
If oxygen, aluminum, and wax were heated to 100 0C, what state would
they be in? Super Heated Water
Super Cooled Water
solid
Oxygen
Aluminum
Wax
100
liquid
gas
mp (oC)
bp(oC)
-218
-183
660
2327
solid
150
liquid
50
100
State
100
gas
Name
Co2(C2O4)3.12H2O
Co
Co
3+
C2O42-
3+
C2O42C2O42-
Cobalt III oxalate dodecahydrate
Name
Sn3(PO3)4 .8H2O
Tin IV phosphite octahydrate
Balance
__C24H50(s) + 36.5
__ O2(g)

24
__ CO2(g) +
25
__ H2O(g)
25 O
48 O
73 O
Workbook
Assignment # 3