AC002 3 Gas+Liquid+Solid+3+%5BCompatibility+Mode%5D (1)

8/3/2019 AC002 3 Gas+Liquid+Solid+3+%5BCompatibility+Mode%5D (1)

1/9

9/20/2011

1

ASC0302_3_Gas Liquid Solid 3 1

Tauhid

Adakah kamu mempersaksikan ketika hampir kematianYaakub? Ketika ia bertanya kepada anaknya: Siapakahsembahanmu sesudah wafatku? Mereka menjawab: Tuhannenek moyangmu Ibrahim, Ismail dan Ishak, iaitu TuhanYang Maha Esa. KepadaNyalah kami menyerahkan diri

{Maksud Al-Quran}



Persediaan awal menghadirikelas

Strategi menghadiri kelas

Mencatit nota semasa di kelas Menyemak nota di kelas


1. Tahu tajuk = > Tanya Guru /

Pensyarah

2. Dapatkan buku berkaitan tajuk

3. Buat bacaan awal

4. Catit nota (peta minda)


Belajar Berkesan

Pilih tempat yang sunyi / nyaman

Pastikan masa belajar adalah sama setiap hari(routine)

Jangka Masa yang digunakan untuk satu-satusesi jangan melebihi 30 minit

Selepas setiap 30 minit, luangkan masa untukrehat selama 5 minit (untuk minum air, cucimuka, solat sunat dll)

Nilai pembelajaran anda selepas setiap sesi


Gas, Liquid and Solid


2/9

9/20/2011

2


Gas - Gas Laws

Liquid Physical Properties ofLiquids

Solid Types of solids, properties ofsolids and close packings

Matters


Properties can be understood in terms of how tightly the

molecules are packed together and the strength of the

intermolecular attractions between them.


Intermolecular attractions determine howtightly liquids and solids pack

Two important properties that depend onpacking are compressibility and diffusion

Compressibility is a measure of the ability ofa substance to be forced into a smallervolume

Solids and liquids are nearly

incompressible because they contain verylittle space between particles


Properties of LiquidsProperties of Liquids

DIFFUSION

Occurs in gases & liquids

The spontaneous mixing ofdifferent particles duethermal/kinetic energy of theirrandom motion


Properties of Liquids

Cohesive & Adhesive forces

Attractive forces(a)(a) CohesionCohesion = intermolecular attraction between like

particles

(b) Adhesion = intermolecular attraction between unlikemolecules

WettingWetting(a)(a) Cohesive force > Adhesive forceCohesive force > Adhesive force = Liquid has high

surface tension & poor wetting action

(b) Cohesive force < Adhesive forceCohesive force < Adhesive force = Liquid has lowsurface tension & good wetting property

Capillary actionCapillary actionWhen a small vertical tube is dipped into a liquid, the meniscusis higher or lower depending on the strength of the cohesive oradhesive forces.


Properties of LiquidsProperties of LiquidsCapillary actionCapillary action

Cohesion= intermolecular attraction betweenlike molecules

Adhesion= attraction between unlike molecules

AdhesionAdhesionStrongerStronger

CohesionCohesionStrongerStronger


3/9

9/20/2011

3


Properties of Liquids

CAPILLARY ACTIONCAPILLARY ACTION

It is the competition between 2opposite forces

Attraction between Hg atoms >Attraction between Hg atoms >

attraction between Hg & glassattraction between Hg & glass

Attraction between HAttraction between H22O molecules


4/9

9/20/2011

4

WETTING AND ROLEOF SURFACTANTS

ASC0302_3_Gas Liquid Solid 3 19 ASC0302_3_Gas Liquid Solid 3 20

Wetting is the spreading of a liquidacross a surface to form a thin film

For wetting to occur, the intermolecularattractive force between the surface andthe liquid must be about as strong aswithin the liquid itself

Surfactants are added to detergents tolower the surface tension of water

The wetter water can then gets betteraccess to the surface to be cleaned

VISCOSITY


Viscosity is the resistance to changingthe form of a sample

Gases have viscosity, but respond almostinstantly to form-changing forces

Solids, such as rocks, normally yield toforces acting to change their shape veryslowly

Liquids are what most people associatewith viscosity

Viscosity is also called internal friction

because it depends on intermolecularattractions and molecular shape


Acetone is a polar molecule and experiences dipole-dipole

and London forces. Ethylene glycol, which also has ten

atoms, also participates is hydrogen-bonding. The

viscosity of ethylene glycol is larger than the viscosity of

acetone.


Phase Changes


5/9

9/20/2011

5


A change in state is called a phasechange

Evaporation is the change in state

from liquid to gas

Sublimation is the change from solidto gas

Both deal with the motion ofmolecules

You have also probably noticed thatthe evaporation of liquids produce acooling effect


The rate of evaporation depends onthe temperature, surface area, andstrength of the intermolecularattractions

Molecules that are able

to escape from the

liquid have kinetic

energies larger than the

average. When theyleave, the average

kinetic energy of the

remaining molecules is

less, so the temperature

is lower.


For a given liquid, the rate ofevaporation per unit surface area isgreater at a higher temperature

At higher

temperature, the total

fraction of molecules

with kinetic energy

large enough to

escape is larger so

the rate of

evaporation is larger.


Similar equilibria are reached inmelting and sublimation

At the melting point a

solid begins to change

into a liquid as heat is

added. As long no heat

is added or removed

melting (red arrows)

and freezing (black

arrows) occur at the

same rate an the

number of particles in

the solid remains

constant.


When molecules evaporate, the

molecules that enter the vapor phaseexert a pressure called the vaporpressure

The equilibrium vapor pressure is thevapor pressure once dynamic equilibriumhas been reached

The equilibrium vapor pressure is usuallyreferred to as simply the vapor pressure

Vapor pressures can be measured usinga manometer


The boiling point of a liquid can be

defined as the temperature at whichthe vapor pressure of the liquid isequal to the prevailing atmospheric

pressure

The normal boiling point is the

temperature at which the vaporpressure is 1 atm

Molecules with higher intermolecularforces have higher boiling points


6/9

9/20/2011

6


Solids


Properties of Gas, Liquidand Solid

Solid Types of solids, properties of solids and close packings


STATES OF MATTER

SOLID:

a form of matter that has a rigid,fixed volume and shape. Solids aregenerally arranged with uniquesymmetrical regularity. Solids aretightly held togetherwith littlespace between the molecules (or

atoms), they are incompressible.Strong electrostatic forces, whichvary from compound to compound,hold the molecules together.


Structures, Properties, andApplications of Solids

When substances freeze, or separate

as a solid from solution, they tend toform crystals

Crystals have highly regular featuresand are said to possess symmetry orbe symmetrical


The Solid State

Ice is only one form of a solid.

Crystalline solids have ordereduniform arrangement of theatoms. Some crystalline solids

are diamonds, metals, andsalts.

Amorphous solids aredisordered and do not breakcleanly. Some amorphoussolids are glass and plastics.

All solids have some molecularmotion. All solids havevibrational modes of energy.


Crystals can be divided into four types:

ionic, molecular, covalent, and metallic Ionic crystals have cations and anions at

the lattice sites

Tend to be brittle, have high meltingpoints, and are nonconducting in thesolid phase and conducting in the liquidphase.

Molecular crystals have neutral moleculesat the lattice sites

Due to the relatively weak intermolecularattractions, solids made from smallmolecules tend to be soft with lowmelting points. They are nonconductingin both the liquid and solid phase.


7/9

9/20/2011

7


Covalent crystals have atoms at thelattice sites covalently bonded to otheratoms These are also called network solids and

the crystal is essentially one large molecule.A typical example is diamond which is veryhard, has a very high melting point, and is anonconductor of electricity.

Each carbon atom in

diamond is covalently

bonded to four others at

the corners of a

tetrahedron. The structure

extends throughout the

entire crystal.


Metallic crystals have cations at the lattice sitessurrounded by mobile electrons

Metallic crystals conduct heat and electricity well,have metallic luster, and tend to have highmelting points.

A highly simplified view of

a metallic solid. Metal atoms

lose valence electrons to the

solids as a whole and existas positive ions surrounded

by a mobile sea of

electrons.



Figure 12.26 The crystal lattice and the unit cell


How many lattice points &/or atomsHow many lattice points &/or atoms"belong" to a unit cell ?"belong" to a unit cell ?

CornersCorners : - Points at the corner of the cell are sharedby the surrounding unit cells, so each one is shared by8 in total and is only "worth" 1/81/8 to each cellto each cell.

FacesFaces : - these lattice points are shared by 2 cells,each one is "worth" 1/21/2 to each cellto each cell.

BodyBody : - this is the sole possesion of that cell, worth 11to each cellto each cell..

Total number lattice pointsTotal number lattice points ::

Primitive cubicPrimitive cubic = 8(1/8) == 8(1/8) = 11

FCCFCC = 6x1/2 + 8(1/8) == 6x1/2 + 8(1/8) = 44

BCCBCC = 8(1/8) + 1 == 8(1/8) + 1 = 22


8/9

9/20/2011

8


Atoms per CellAtoms per Cell


Figure 12.27 (1 of3)

The three cubic unit cells

Simple Cubic

coordination number = 6

Atoms/unit cell = 1/8 * 8 = 1

1/8 atom at8 corners


The simplest and most symmetricalthree- dimensional lattice is called asimple cubic or primitive cubiclattice

(a) A simple cubic unit cell showing the lattice points.

(b) A portion of a simple cubic lattice. (c) Only a portion

of each atom of a substance that forms a simple cubic

lattice lies within a particular unit cell.


Only 1/8 of each atom lies in aparticular simple cubic unit cell

Each simple cubic unit cell contains:

Two additional cubic lattices are

possible: face-centered cubic (fcc) andbody-centered cubic (bcc)

atom1corner

atom1/8corners8


Figure 12.27 (2 of 3) The three cubic unit cells

Body-centeredCubic

coordination number = 8

1/8 atom at8 corners

1 atom atcenter

Atoms/unit cell = (1/8*8) + 1 = 2


Figure 12.27 (3 of 3) The three cubic unit cells

Face-centeredCubic

coordination number = 12Atoms/unit cell = (1/8*8)+(1/2*6) = 4

1/8 atom at

8 corners

1/2 atom at6 faces


9/9

9/20/2011

9


A unit cell of NaCl shows how to weigh lattice points:

corners have a weight of 1/8, faces a weight of 1/2, and

edges a weight of 1/4. This unit cell contains four sodium

and four chloride ions.



A change in state is called a phase

change

Evaporation is the change in statefrom liquid to gas

Sublimation is the change from solidto gas

Both deal with the motion ofmolecules

You have also probably noticed thatthe evaporation of liquids produce acooling effect


Figure 12.2 Phase changes and their enthalpy changes

AC002 3 Gas+Liquid+Solid+3+%5BCompatibility+Mode%5D (1)

Documents