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Chemistry of Matches
P4S3 + KClO3 P2O5 + KCl + SO2
tetraphosphorustrisulfide
potassiumchlorate
diphosphoruspentaoxide
potassiumchloride
sulfurdioxide
The substances P4S3 and KClO3 are both present on the tip of a strike anywhere match. When the match is struck on a rough surface, the two chemicals (reactants) ignite and produce a flame.
Charles H.Corwin, Introductory Chemistry 2005, page 182
Safety matchesSafety matches
The products from this reaction are P2O5, KCl, and SO2,the last of which is responsible for the characteristic sulfur smell.
Strike anywhere matchesStrike anywhere matches
The substances P4S3 and KClO3 are separated. The P4S3 is onthe matchbox cover. Only when the chemicals combine do they react and produce a flame.
block of wood: length = 2.0 m width = 0.9 m height = 0.5 m
block of wood: force = 45 N
2.205 pounds = 1 kilogram 10 Newton (9.8 N)
Force versus Pressure
Area = 0.9 m x 2.0 m = 1.8 m2
Area = 0.5 m x 2.0 m = 1.0 m2
Area = 0.5 m x 0.9 m = 0.45 m2
area
force Pressure
2m 1.8
N 45.0 Pressure
2m 1.00
N 45.0 Pressure
2m 0.45
N 45.0 Pressure
block of wood: length = 2.0 m width = 0.9 m height = 0.5 m
25 N/m2 45 N/m2 100 N/m2
Herron, Frank, Sarquis, Sarquis, Schrader, Kulka, Chemistry, Heath Publishing,1996, page Section 6.1
During a“physical change”
a substance changes some physical property…
During a“physical change”
a substance changes some physical property…
H2O
…but it is still the same material with the same chemical composition.
…but it is still the same material with the same chemical composition.
H2Ogas
solid
liquid
Chemical Property:Chemical Property:
The tendency of a substance to change into another
substance.
The tendency of a substance to change into another
substance.
caused by iron (Fe) caused by iron (Fe) reacting with oxygen (Oreacting with oxygen (O22) )
to produce rust (Feto produce rust (Fe22OO33))
Steel rustingSteel rusting::
4 Fe + 3 O4 Fe + 3 O22 2 Fe 2 Fe22OO33
Chemical Change:Chemical Change:
Any change involving a rearrangement of atoms.Any change involving a
rearrangement of atoms.
Chemical Reaction:Chemical Reaction:
The process of a chemical change...The process of a
chemical change...
During a“chemical reaction”new materials are
formed by a change in the way atoms are bonded together.
During a“chemical reaction”new materials are
formed by a change in the way atoms are bonded together.
Physical and Chemical PropertiesExamples of Physical Properties
Boiling point Color Slipperiness Electrical conductivity
Melting point Taste Odor Dissolves in water
Shininess (luster) Softness Ductility Viscosity (resistance to flow)
Volatility Hardness Malleability Density (mass / volume ratio)
Examples of Chemical Properties
Burns in air Reacts with certain acids Decomposes when heated
Explodes Reacts with certain metals Reacts with certain nonmetals
Tarnishes Reacts with water Is toxic
Ralph A. Burns, Fundamentals of Chemistry 1999, page 23Chemical properties can ONLY be observed during a chemical reaction!
The formation of a mixture
The formation of a mixture
The formation of a compound
The formation of a compoundChemical Change
Chemical Change
Physical Change
Physical Change
Physical & Chemical Changes
Limestone,CaCO3
crushing
PHYSICALCHANGE
Crushed limestone,CaCO3
heating
CHEMICALCHANGE
PyrexPyrex
CO2
CaO
Lime andcarbon dioxide,
CaO + CO2