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Chapter 6 Properties Of Matter, download - Coggle Diagram
Chapter 6 Properties Of Matter
States of matter
solid // has a fixed shape and volume
liquid // varying shape and has an upper surface
Plasma // superheated ionized gas consisting of charged particles
gas // has no fixed shape or volume
Changes of state
Matter can change between states (physical change rather than chemical change) when the temperature or pressure of a system is changed
solid to liquid =melting
liquid to solid=freezing
liquid to gas=vaporization
gas to liquid=condensation
solid to gas=sublimation
gas to solid=deposition
Heating causes the particles of matter to absorb energy, move more vigorously and separate further apart
Cooling causes the particles to move less vigorously and come closer together
Properties of Gases and Gas Laws
Three variables are used to measure gases: pressure,volume, and temperature
Volume
a gas is equal to the volume of the container that holds the gas
Temperature
is the heat energy due to the motion of the gas particles
Pressure
-is force per area
Pressure is the result of collisions between the gas particles and the collisions between particles and the walls of the container that holds the gas
Boyle’s Law
The volume of a given mass of a gas is inversely proportional to pressure at constant temperature
P1V1=P2V2
Charles Law
The volume of a given mass of a gas is proportional to absolute temperature at constant pressure
V1/T1=V2/T2
Avogadro’s Law
The volumes of gases are proportional to the number of atoms or molecules
The Ideal Gas Law
PV = nRT
Where:
P =pressure in atm
T =temperature in Kelvin
n= number of moles
R is the gas constant = 0.0821 L atm mol-1 K-1
Gay-Lussac's Law
The pressure of a given mass of a gas is proportional to absolute temperature at constant volume
P1/T1=P2/T2
Dalton's Law of Partial Pressure
Ptot = PA + PB +PC +....
PH2O vapor + Pdry gas = Ptot (measured)
PA = nA (RT/V) or PA = XA x Ptot
PB = nB (RT/V) or PB = XB x Ptot
Real Gases and van der Waals Equation
Gases behave like ideal (perfect) gases at low pressure and high temperature (High pressure and low temperature causes gases to behave non-ideally)
(P+n^2a/V^2)(V-nb)=nRT
a= constant for molecular attraction (units: atm L2 mol-2)
b= constant for volume of molecules (units: L mol-1)
Kinetic Theory of Gases
The volumes of gas particles are negligible (very small)
Intermolecular forces do not exist between gas particles
Gas particles move in random motions and collide without energy loss (elastic collisions)
The kinetic energy of a gas is directly proportional to absolute temperature
KE = 1/2mu2 = 3/2kT
Properties of Liquids
Viscosity is a measure of the resistance to flow
Viscosity is a measure of the resistance to flow
Liquids tend to become more viscous as the size of molecules become larger, as the amount of intermolecular bonding increases and the temperature decreases
The force that controls the shape of the liquid is called the surface tension. Below the surface of the liquid, the force between molecules is the same in all directions, but at the surface the force of attraction pulls the molecules into the liquid
Vapor Pressure
The vapor pressure of a liquid is the pressure of the vapor(gas) above the liquid at a given temperature
A liquid open to the air will (over time) evaporate completely; however in a closed container some of the evaporated molecules may return to the liquid
Over time an equilibrium will be established
The gas pressure under this equilibrium condition is called the vapor pressure.The boiling points of most liquids are proportional to the vapor pressure
Colligative Properties
depend only on the number of dissolved particles in solution and not on their identity
The 4 colligative properties for liquids are
Vapor pressure lowering, Boiling point elevation, Freezing point depression and Osmotic pressure
Vapor Pressure Lowering
The vapor pressure of a solution containing nonvolatile solute is lower than the pure solvent
The Raoult's Law describes the vapor pressure lowering:
change of Psolution = Xsolute Po
where, Psolution is the vapor pressure difference
Xsolute is the mole fraction of the solute
Po is the vapor pressure of the pure solvent
Boiling Point Elevation
The boiling point of a solution containing nonvolatile solute is greater than the boiling point of the pure solvent
The change in boiling point is given by the van't Hoff equation for boiling point:
Tb = Kb x m
where, Tb = boiling pt of solution - boiling pt of solvent
Kb is the boiling pt elevation constant
m is the molality of the solution
Freezing Point Depression (Lowering)
The change in freezing point is given by the van't Hoff equation for freezing point:
Tf = - Kf x m
where, Tf = freezing pt of solution - freezing pt of solvent
Kf is the freezing pt depression constant
m is the molality of the solution
Osmotic Pressure
Osmosis refers to the flow of solvent molecules past a semi permeable membrane
The equation relating the osmotic pressure of a solution to its concentration is II = M R T
where, II is osmotic pressure
R is the gas constant
T is the absolute temperature
M is the molarity of the solution
Properties of Solid
Crystalline solids
The atoms, molecules or ions are arranged in a regular pattern
They exhibit anisotropic properties
Ionic crystals
Consist of positive and negative ionsalternately arranged
Have high melting points, tend to be hard or brittle
Conduct electricity in the molten or soluble state (eg NaCl, CaCl2)
Molecular crystals
Have low melting points and tend to be soft and non conductors (eg water, solid CO2)
Consist of uncharged atoms/molecules
Covalent crystals
A network of covalently bonded atoms forming a gigantic molecule
Have high melting points and tend to be hard and non conductors (eg Diamond (C),quartz, SiO2)
Metallic crystals
Melting points and hardness depend on the nuclear charge and electrons and conductors (eg Cu, Hg, Na)
One example crystalline in our daily life:Diamond
Diamond is the most decent example of crystalline solids and is widely used in making beautiful jewelry items
Amorphous solids
Unit Cells, Crystal Lattices and Crystal System
A unit cell is the smallest basic unit of a crystal that can be repeated in three dimensions throughout the crystal lattice
The cubic system
Simple cubic lattice
Body-centered cubic lattice
Face-centered cubic lattice
Atomic radius and Density
Simple cubic lattice (atoms touch each other along the unit cell edge)For similar atoms: 2r = a
where, r = atomic radius a = length of unit cell edge
Face-centered cubic lattice
For similar atoms: 4r = a2
For different ions: (2rM+) + (2rX-) = a2
The crystal structure of NaCl
If Na+ ions (small spheres) are drawn at the corners, then Na+ ions are also present at each face of the unit cel
If Cl- ions (large spheres) are drawn at the corners, then Cl- ions are also present at each face of the unit cell
Close packing and Coordination number
A coordination number is defined as the number of spherical units that surround a given unit. Efficient packing of atoms in solids are known as close-packing
