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States of Substance
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States of substances
According to their states, substance were
grouped into 3 parts.
Shape of Substances Shape characteristic Volume characteristic
Solid Its shape is permanent Permanent
Liquid Its shape is always changing,
following its container
Permanent
Gas Its shape is always changing,
following and filling its
container
Changing
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Change of state of substance
Solid
LiquidGas
condensing
steaming
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From the diagram before, the conclusions are:
Melting is the state changing from solid to liquid
F
reezing is the state changing from liquid to solid Steaming is the state changing from liquid to gas
Condensing is the state changing from gas to
liquid
Crystallizing is the state changing from gas to solid
Sublimating is the state changing from solid to gas
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Molecule and particle
Molecule is the smallest division (of object)
having same characteristics as the original
substance.
Molecule formed by another smaller particle
called atom.
Two or more atoms merged would forming
molecule. Molecular theory or atomical theory can be used
to explained the change of state of substance.
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Solid having permanent shape because of itsclosed-each other and well-regulated molecules.It causes the molecule of solid is hard toseparated. The movements of molecules of solidare only vibrating and rotating on their place.
Liquid having changed state and always adapt toits container, but its movements are more freethan the movement of solid. The molecules of
liquid could easily moving, but hardly leavingtheir group because there is any pull forcebetween them.
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Gas having changed shape and volume because
of its molecule can freely moving. The space
between the molecules is farer than the size of
the molecules, so the pull force is very weak.
solid liquid gas
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Differentiating cohesion and adhesion
Cohesion is a pull force between the particles
of the same substance.
Adhesion is a pull force between the particlesof the different substance.
Example:
Water wetting the glass and shaping wide because
of the cohesion inter-water molecules is bigger
than the adhesion between the water molecules
and the glass molecules.
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Meniscuses (concave and convex)
Cohesion and adhesion are influencing thesurface shape of liquid in its container.
Concave
meniscus
Convex
meniscus
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The surface shape of liquid in the react tube thatformed concave is called concave meniscus. Thishappened because of the cohesion inter-water
molecules is smaller than the adhesion of thewater molecules and the glass molecules.
The surface shape of liquid in the react tube thatformed convex is called convex meniscus. This
happened because of the cohesion inter-mercurymolecules is bigger than the adhesion of themercury molecules and the glass molecules.
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Concave meniscus and convex meniscus are
causing different contact angle between the
area of container (tube) with the surface of
liquid.
Concave meniscus causes an acute (90 )
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Capillarity
Capillarity is the tendency of liquid rise or set inthe capillary tube or small tube.
Cohesion and adhesion are influencing the
capillarity tendency. When a glass capillary tube is half-dyed in water,
the water will rise in the glass vessel of thecapillary tube.
When a glass capillary tube is half-dyed inmercury, the mercury will set in the glass vesselof the capillary tube.
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Water Water in
capillary
tube
Mercury Mercury in
capillary
tube
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Examples of natural capillarity tendency:
In some plants, their tip root can rise up to the
leaves
The gasoline rise up to the wicks of stove
The inner wall in some house will wet when the
rain comes (when the outer wall contacted with
the raindrop, it will wet, and it can be seep to theinner wall of the house)
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