perties of Solids, Liquids, Gas Prepared by :- Abhishek
Transcript
1. Prepared by :- Abhishek
2. Observing the Natural World of Matter What Is Matter? Matter
is the material or stuff everything is made of. What are you doing
if you are observing matter? Observing matter means to carefully
explore all of its properties. Look around the room and identify
some matter. What are some physical properties matter can have?
Color, texture, odor, shape What are two properties that all matter
share? All matter has mass and takes up space. What are the three
states of matter? solid, liquid, and gas
3. Solid, Liquid, Gas (a) Particles in solid (b) Particles in
liquid (c) Particles in gas
4. Ice H2O(s) Ice Photograph of ice model Photograph of
snowflakes
5. Liquid H2O(l) Water In a liquid molecules are in constant
motion there are appreciable intermolecular forces molecules are
close together Liquids are almost incompressible Liquids do not
fill the container
6. Gas H2O(g) Steam
7. Liquids The two key properties we need to describe are
EVAPORATION and its opposite CONDENSATION add energy and break
intermolecular bonds EVAPORATION release energy and form
intermolecular bonds CONDENSATION
8. States of Matter Solid Liquid Gas Holds Shape Fixed Volume
Shape of Container Free Surface Fixed Volume Shape of Container
Volume of Container heat heat
9. Some Properties of Solids, Liquids, and Gases Property Solid
Liquid Gas Shape Has definite shape Takes the shape of Takes the
shape the container of its container Volume Has a definite volume
Has a definite volume Fills the volume of the container Arrangement
of Fixed, very close Random, close Random, far apart Particles
Interactions between Very strong Strong Essentially none
particles
10. To evaporate, molecules must have sufficient energy to
break IM forces. Molecules at the surface break away and become
gas. Only those with enough KE escape. Breaking IM forces requires
energy. The process of evaporation is endothermic. Evaporation is a
cooling process. It requires heat. Evaporation
11. Change from gas to liquid Achieves a dynamic equilibrium
with vaporization in a closed system. What is a closed system? A
closed system means matter cant go in or out. (put a cork in it)
What the heck is a dynamic equilibrium? Condensation
12. As time goes by the rate of vaporization remains constant
but the rate of condensation increases because there are more
molecules to condense. Equilibrium is reached when: Rate of
Vaporization = Rate of Condensation Molecules are constantly
changing phase dynamic The total amount of liquid and vapor remains
constant equilibrium Dynamic Equilibrium
13. Vaporization is an endothermic process - it requires heat.
Energy is required to overcome intermolecular forces Responsible
for cool earth Why we sweat Vaporization
14. Energy Changes Accompanying Phase Changes Solid Liquid Gas
Melting Freezing Deposition CondensationVaporization Sublimation
Energyofsystem
15. Density & Specific gravity Density:-The density of a
material is equal to its mass divided by its volume and has units
of 3 . It is of two types:- Bulk Density Particle Density What is
porosity? Surface Gravity: SG = density of liquid / density of
water
16. Viscosity Viscosity may be thought of as a liquids internal
resistance to flow. A liquid can be envisaged as having a series of
layers and when it flows over a surface, the uppermost layer flows
fastest and drags the next layer along at a slightly lower
velocity, and soon through the layers until the one next to the
surface is stationary.
17. Van der Waals Forces and the Properties of Liquids
Viscosity increases with increasing intermolecular forces because
increasing these forces increases the resistance to flow. Other
factors, such as the possibility of molecules tangling together,
affect viscosity. Liquids with long molecules that tangle together
are expected to have high viscosities.
18. Continue Pseudo plastic fluid Viscosity decreases as the
shear rate increases (e.g. emulsions, and suspensions such as
concentrated fruit juices and puries) Dilatant fluid Viscosity
increases as the shear rate increases. (This behaviour is less
common but is found with liquid chocolate and corn flour
suspension.) Binghamor Casson plastic fluids There is no flow until
a critical shear stress is reached and then shear rate is either
linear (Bingham type)or non-linear ( Casson type)(e.g. tomato
ketchup) Thixotropic fluid The structure breaks down and viscosity
decreases with continued shear stress ( mostcreams) Rheopectic
fluid The structure builds up and viscosity increases with
continued shear stress ( e.g.whippingcream)
19. Surface Tension Surface tension is the tendency for liquid
surface to contract. Depends on attractive forces Compounds that
interfere with the forces and reduce surface tension are called
surfactants.
20. Van der Waals Forces and the Properties of Liquids Surface
tension increases with increasing intermolecular forces. Surface
tension is the energy needed to reduce the surface area of a
liquid. To increase surface area, it is necessary to pull molecules
apart against the intermolecular forces of attraction.
21. The molecular basis of surface tension. hydrogen bonding
occurs in three dimensions hydrogen bonding occurs across the
surface and below the surface the net vector for attractive forces
is downward
22. Shape of water or mercury meniscus in glass. adhesive
forces stronger cohesive forces H2O capillarity Hg
23. The striking beauty of crystalline solids.
24. portion of a 3-D lattice The crystal lattice and the unit
cell. lattice point unit cell portion of a 2-D lattice unit
cell
25. Phase Changes
26. Phase Changes solid liquid gas melting freezing vaporizing
condensing sublimination Energy absorbed Energy released