che 112 - module 1 chapter 12 lecture notes. properties of gases gases completely fill their...

CHE 112 - MODULE 1

CHAPTER 12

LECTURE NOTES

Properties of Gases

Gases completely fill their container in a uniform manner

Gases are compressible Gases have low densities Gases will exert pressure as the gas

molecules collide with the inner surfaces of their container

Kinetic Molecular Theory of Gases

A gas is composed of particles that are very small compared with the average distance between the individual particles.

Gas particles are in constant straight line, random motion.

Collisions are elastic. Attractions between particles are negligible. The average kinetic energy (energy of

motion) of these particles is directly proportional to the temperature in Kelvin.

Boyle’s Law

P 1/ V; PV = k when T is constant P = pressure & V = volume The pressure is inversely proportional to

the volume. As the pressure increases, the volume

decreases; and as the pressure decreases, the volume increases.

P1V1 = P2V2

Charles Law

V T; V = kT when P is constant V = volume & T = temp in Kelvin The volume is directly proportional to

the temperature. As the temp increases, the volume

increases: and as the temp decreases, the volume decreases.

V1/T1 = V2/T2

Combined Gas Law

Combination of Boyle’s and Charle’s Laws

P1V1 / T1 = P2V2 / T2

Used when all the conditions of the same gas changes, and nothing remains constant.

Avogadro’s Law

The molar volume is defined as the volume of 1 mole = 22.4 L for any gas at Standard Temperature and Pressure (STP)

STP means 273.15K (0°C) and 1 atm (760mm Hg)

Ideal Gas Law

PV = nRT P = pressure (atm) V = volume (L) n = number of moles (mol) R = gas constant = 0.08206 (L·atm/mol·K) T = temperature (K)

Real Gas Law

As temperatures and pressures deviate from STP, the Ideal Gas Law no longer holds true.

The Van der Waals equation is used to compensate for intermolecular forces and molecular volume in non-ideal conditions.

(P+a[n/V]2)(V-bn) = nRT

CHE 112 - MODULE 1

CHAPTER 13

LECTURE NOTES

Intermolecular Forces Dipole-dipole interactions

– polar molecules attract by charge Dipole-induced dipole forces

– a dipole can be induced by a polar species London dispersion forces

– momentary attraction of non-polar molecules Hydrogen bonding

– attraction of H-O, H-N and H-F with other highly electronegative atoms

Water and Hydrogen Bonding

The O of a water molecule attaches to four other water molecules

The hydrogen bonded water creates a tetrahedral of H around the O

Water freezes into a water lattice that is ordered and has spaces within the repeated lattice crystal

DNA and Hydrogen Bonding

Deoxyribonucleic acid (DNA) is a chain of phosphates linked to sugars

Bonded to each sugar is either a thymine, guanine, cytosine, or adenine base molecule

The base molecules on one chain interact through hydrogen bonding with base molecules on another chain

This pairing of chains produces the double helix of DNA

Properties of Liquids

Vaporization = H°vap standard molar heat of vaporization– liquid gas, endothermic process– liquid vapor, vapor pressure– boiling point

Surface tension - energy to break the surface Capillary action - adhesive forces Viscosity - resistance to flow

Vapor Pressure

Vapor pressure = the partial pressure of the vapor over the liquid, measured at equilibrium– As surface molecules gain sufficient KE, they

escape the liquid into vapor above the liquid– As the # of vapor molecules increase, more

collisions will occur above the liquid– More molecules will collide at the surface and

condense back into the liquid state– Rate of condensation = rate of vaporization– At this point, the partial pressure exerted = vapor

pressure of the liquid– As the temperature , KE , vapor pressure

Boiling Point Boiling point = the temperature at which the

vapor pressure of a liquid = the vapor pressure exerted on the liquid*– As temperature , vapor pressure ; when the

vapor pressure = atmospheric pressure, stable bubbles of vapor form

– The liquid begins to “boil”– Once boiling begins, it will continue to boil as long

as heat is supplied or until all the liquid has been converted to vapor

*At 1atm, water will boil at 100°C, but at the top of Whiteface, water will boil at a lower temperature

Types of Solids

Ionic compounds Metallic materials Molecular compounds Network solids Amorphous materials

Crystalline vs Amorphous

Crystalline = has a defined structure Amorphous = random (undefined

structure)

Cubic Units

Simple cube Face-centered cube Body centered cube

Phase Diagrams

Phase Diagram shows all the phases of matter and their relationships for different types of matter– Solid– Liquid– Gas– Triple point– Critical point

Changes of States

Melting (solid > liquid) Freezing (liquid > solid) Vaporization (liquid > vapor) Condensation (vapor > liquid) Sublimation (solid > vapor) Condensation by deposition (vapor >

solid)

CHE 112 - MODULE 1

CHAPTER 14

LECTURE NOTES

Units of Concentration

Molarity (M) = moles of solute Liters of solution

Molality (m) = moles of solute Kg of solvent

Mole fraction (XA) = moles of A moles of solution

Units of Concentration (cont.)

Weight % A = mass of A X 100%

total mass

Parts per million (ppm) = 1g of matter

mass million g

1ppm = 1mg/L = 1g/ml

Solutions

Saturated - solution containing the maximum amount of dissolved solvent

Unsaturated - Less than saturated

Supersaturated - more than saturated

Liquid/Liquid Interaction

Miscible - liquids that mix well due to like polarity

Immiscible - liquids that do not mix because one is polar and the other is non-polar

“Likes dissolve likes”

Solids Dissolved in Liquids

Hydrated - ionic solids dissolve when surrounded by polar water molecules in solution

Heat of Solution (Hsoln) = net energy change for the solution process– Exothermic rxn yield more soluble cmp– Endothermic rxn yield insoluble cmp

Enthalpy of Hydration

The energy involved with hydrating an ion depends on 3 things:– distance between the ion & dipole (closer

the stronger attraction)– charge on the ion (higher the stronger)– polarity of the solvating molecule (greater

the magnitude of the dipole the stronger)

Vapor Pressure Lowering

VPL = a colligative property (concentration dependent) equal to the vapor pressure of pure solvent minus the vapor pressure of the solution– Occurs when a nonvolatile solute is mixed

with a solvent that have similar structure Psolv = Psolv - Psolv

Raoult’s Law

Psolv = XsolvP solv

– Psolv Xsolv

– Vapor pressure of the solution is lower than the that of the pure solvent

– CD-ROM Screen 14.7

Psolv = -XsolvPsolv

Freezing Point Depression

Freezing point depression is a colligitive property equal to the freezing point of the pure solvent minus the freezing point of the solution

Tfp = kfp msolute

Tfp = freezing point depression– kfp = freezing point depression constant (for water it

is -1.86°C/m)– msolute = molal concentration

Boiling Point Elevation

Boiling point elevation is a colligitive property equal to the boiling point of the solution minus the boiling point of the pure solvent

Tbp = kbp msolute

Tbp = boiling point elevation

– kbp = boiling point elevation constant (for water it is 0.512°C/m)

– msolute = molal concentration

Colloids

Dispersion of particles of one substance (dispersed phase) throughout another substance or solution (the continuous phase)

Appears homogeneous Particle sizes are between 10 – 2000

angstroms (1x10-10m) in diameter

Micelle

Aggregate of molecules that have a polar end and a nonpolar end.– Nonpolar ends will meet together in the

middle, while the polar ends will be attracted outward toward the water molecules