Review Chapter 6 & 7:

General, Organic, & Biological Chemistry

Janice Gorzynski Smith

2

Chapter 6 & 7 Concepts Energy

conversions, conservation of energy Breaking bonds requires E, forming bonds releases E

Endothermic & Exothermic Reactions Energy diagrams, Activation Energy, heat absorbed or released

Factors affecting rates of reactions Concentration, temperature, catalysts

Equilibrium Equilibrium constant expressions Le Chatlier Principle

States of matter: g, l, s & their properties Effect of intermolecular forces on behavior Gas laws: combined, ideal, & dalton’s law partial pressure

Intermolecular forces London-Dispersion, Dipole-Dipole, Hydrogen-Bonding Relative strength, importance in g, l, s behavior

Phase Changes Navigate a heating/cooling curve Enthalpy of phase changes

Equations & Conversions

1 cal = 4.184 J

1,000 J = 1 kJ

1,000 cal = 1 kcal

1 kcal = 4.184 kJ

PV = nRT

R = 0.0821L • atmmol • K

R = 62.4L • mm Hg

mol • K

P1V1

T1

=P2V2

T2

Ptotal = PA + PB + PC

Equations to memorize in red

K =[C]c [D]d

[A]a [B]b=

[products][reactants]

Energy of Reactions

E

Reactants

ProductsEXOTHERMIC

ENDOTHERMIC

Heat released

Heat absorbed

ENDOTHERMICHeat + A + B C + D

Products have weaker bonds and a higher energy then Reactants.

Heat is absorbed by the system.ΔE + ΔH +

EXOTHERMICA + B C + D + heat

Products have stronger bonds and a lower energy then Reactants.

Heat is released by the system.

ΔE - ΔH -

Energy required to

break bonds

Energy releasedas bonds

form

ΔH

ΔH

Ea

Ea

Transition State

Rates of Reactions

Increase the Rate of a Reaction

Increase TemperatureIncrease Average KE of particles, so more

likely to collide with enough energy to overcome Ea

Increase Concentration ReactantsIncrease the number of collisions per second

Add a CatalystDecrease Ea

Same likelyhood rxn will happen when particles collide, but more collisions

Greater likelyhood that particles will have enough KE to react

Equilibrium & Le Chatlier’s Principle

a A + b B c C + d D

equilibriumconstant = K =

[C]c [D]d

[A]a [B]b=

[products][reactants]

A + B C + D + heat

reactant Eq Shift product

increase

decrease

increase

decrease

T increase

T decrease

A + B + heat C + D

reactant Eq Shift product

increase

decrease

increase

decrease

T increase

T decrease

K > 1 products favored K < 1 reactants favored K = 1 equilibrium

Intermolecular Forces

London Dispersion Forces

Dipole-Dipole Forces

Hydrogen Bonds

Ion-Dipole Forces

Weakest

Strongest

Forces experienced by states of matterGas < Liquids < Solids

Increasing Average Kinetic Energy

Physical Properties

Property of s, l, g Increases Decreases Example

Boiling Point increasing total intermolecular forces

decreasing total intermolecular forces

Water has a high boiling point because it has H-bonding, dipole, and dispersion forces. It is close to heptane (C7H16), a heavier molecule that only experiences dispersion forces .

Melting Point increasing total intermolecular forces

decreasing total intermolecular forces

The melting point of ionic solids is extremely high compared to water which experiences all other intermolecular forces, but not ion-dipole forces. (NaCl is 1074 K and water is 273 K)

Retention of V & Shape

Increasing intermolecular forces and decreasing T & P

Decreasing intermolecular forces, and increasing kinetic energy of particles or T & P

Gases will fill the volume and shape of the container that holds them, while solids will retain their own shape and volume regardless of the container.

Surface Tension with increasing intermolecular forces

with decreasing intermolecular forces

The molecules on the surface have less neighbors (and therefore less stabilizing intermolecular forces) and so have a higher potential energy, which the material will try to reduce with its shape (sphere): water beading.

Viscosityincreasing intermolecular forces and decreasing temperature

decreasing intermolecular forces and increasing temperature

Not just a property of liquids, also gases and solids. Amorphous solids change shape over time because of their viscosity.

Vapor PressureDecreasing intermolecular forces and increasing temperature

Increasing intermolecular forces and decreasing temperature

Ether has weaker intermolecular forces than water and a higher vapor pressure, so it evaporates much faster then water.

Gas Behavior

Non Rigid Container:Pistonballoon

Rigid Container:Closed Flask

P constantV increase w/ T or

# of moles

V constantP increase w/ T or

# of moles

PV = nRT

P1V1

T1

=P2V2

T2

Ptotal = PA + PB + PC

Phase Changes

SOLID LIQUID GASfusion

freezing

evaporation

condensation

deposition

sublimation

endothermic

exothermic

System absorbs energy from surrounds in the form of heato Requires the addition of heat

System releases energy into surrounds in the form of heat or lighto Requires heat to be decreased

Phase ChangesTE

MPE

RATU

RE

HEAT ADDED

solid

liquid

gas

s <--> l

l <--> g

fusionΔHfus

evaporationor vaporization

ΔHvap

endothermic

endothermic