Matter and Energy

Properties of Matter

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

Pressure

force

pressurearea

Which shoes create the most pressure?

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

PyrexPyrex

O2

H2O

PyrexPyrex

H2O2

Light hastens the decomposition of hydrogen peroxide, H2O2. The dark bottle in which hydrogen peroxide is usually storedkeeps out the light, thus protecting the H2O2 from decomposition.

Sunlight energy

H H

O O