Unit 5-7 IB Chem 1

Final Exam Prep

What 4 characteristics change reaction rates?

• Temperature

• Concentration

• Surface area

• Catalyst

In order for a reaction to occur, what three requirements are there according to collision theory?

• Sufficient Energy

• Effective Collisions

• Proper Orientation

What happens when temperature is increased?

• Average kinetic energy increases

• Frequency of collisions increases

• Energy of collisions increases

• Energy needed for particles to react increases

What happens when concentration is increased?

• Number of particles per volume increases

• Frequency of collisions increases

What happens when surface area is increased?

• Increases exposed particles in a solid state

• Increases frequency of collisions

What happens when a catalyst is added?

• Makes collisions more effective

• Decreases activation energy

• Speeds up reaction

• Changes mechanism of reaction

A catalyst must be…

• chemically unchanged at the end of the reaction

Endothermic reaction properties

• Products less stable

• ΔH > 0

• Requires heat

• Reactant bonds stronger than product bonds

Exothermic reaction properties

• Products more stable

• ΔH < 0

• Releases heat

• Product bonds stronger than reactant bonds

Activation Energy

The energy needed to break existing bonds

• breaking bonds absorbs energy

• creating bonds releases energy

Endothermic phase changes

• Melting

• Sublimation

• Boiling

Exothermic phase changes

• Condensation

• Deposition

• Freezing

Triple point

Temperature and pressure at which all three phases exist in equilibrium

Critical point

The temperature and pressure beyond which a liquid cannot exist

Specific Heat Capacity

The amount of heat energy required to increase the temperature of 1g of a substance 1ºC.

When do kinetic energy changes happen?

When there are changes in temperature

When do potential energy changes happen?

When there are changes of state

Kinetic Molecular Theory states that gases:

• Consist of hard spherical particles

• Particle volumes are insignificant

• Space between particles

• Easily compressed or expanded

• No attractive/repulsive forces

• Gas particles are in random motion

• Collisions between gas particles are elastic

What are the four variables that describe a gas?

• Temperature

• Volume

• Pressure

• Amount

Standard Temperature and Pressure (STP)

Pressure = 100 kPa

Temperature = 273K = 0 ºC

Diffusion of gases

• How quickly gases mix with eachother

• Gases move from higher to lower concentrations

Effusion of gases

• Movement of gas from an area of high concentration to a vacuum

• Gases with lower mass effuse ore quickly than gases with higher mass

Pressure and Volume equation

P1V1=P2V2

Volume and Temperature equation

V1/T1 = V2/T2

Pressure and Temperature equation

P1/T1 = P2/T2

Combined Gas Law

P1V1/T1 = P2V2/T2

Ideal Gas Law

PV=nRT

What does R stand for?

8.31

How many liters is 1 mol at STP?

22.7 L

Ideal Gas Properties

• Made of small particles that have mass

• Empty space/low density

• Particles in constant random straight line motion

• No attractive/repulsive forces

• Particles have no volume

• Collisions are elastic and no kinetic energy is lost.

Real Gas Properties

• Made of small particles that have mass

• Empty space/low density

• Particles can curve

• Small attractive and repulsive forces between particles

• Particles have small volume

• Collisions are inelastic and gas particles lose kinetic energy when they collide

Relationship between particles and pressure

• Less particles = less pressure

Partial Pressure Equations

P total = P1 + P2 + P3

P total = (% occurance as decimal)(P total) + …

Relationship between temperature and vapor pressure

• Higher temperature causes higher vapor pressure

Relationship between IMFs and vapor pressure

• Stronger intermolecular forces cause weaker vapor pressures

Boiling point

The temperature which vapor pressure = atmospheric pressure

How to find vapor pressure

Subtract vapor pressure of water from total pressure of system

Evaporation properties

• Only at surface

• Any temp.

• Fastest particles leave first and avg. kinetic energy decreases

Boiling properties

• Throughout sample

• At specific temp. and pressure

• Energy must be supplied

• Temp. and pressure at which gas and liquid are at equilibrium

Solute

Substance being dissolved

Solvent

Substance doing the dissolving

Solution

Solvent + solute

Solubility rule

“Like-dissolves-like”

4 factors that affect solubility

• Stirring - increases rate of solubility

• Particle size - the smaller the particles the faster it will dissolve

• Temp. - solids increase solubility and gases decrease solubility as temp increases

• Pressure - solids have little to no effect and gases increase solubilty

3 Colligative Properties

• Vapor Pressure Lowering

• Boiling Point Elevation

• Freezing Point Depression

Vapor Pressure Lowering

• More solute lowers vapor pressure

Boiling Point Elevation

• More solute increases boiling point

Freezing point depression

• More solute lowers freezing point

Where is heat in an exothermic equation

In the products (right side)

Where is heat in an endothermic equation

In the reactants (left side)

When pressure increases…

equilibrium shifts to side with fewer moles

When pressure decreases…

equilibrium shifts to side with more moles

Does pressure affect solids and liquids in equilibrium?

No

Acid properties

• Taste sour

• Conduct electricity

• Form H2 gas when react with metals

• Turn blue litmus paper red

Base properties

• Taste bitter

• Feel slippery

• Conduct electricity

• Turn red litmus paper blue

Arrhenius Definitions

• Acids product H+ in aqueous solutions

• Bases produce OH- in water

Bronsted-Lowery Definitions

• Acids donate H+

• Bases accept H+

What acids are weak?

Organic acids

A pH < 7 is

acidic

A pH = 7 is

neutral

A pH > 7 is

basic

pH + pOH =

14

Formula to find pH

-log[H]

Formula to find 10^-pH

Formula to find uncertainty when doing multiplication and division

(uncertainty/measurement)(100)

What does the Law of Conservation say about balanced chemical equations?

The number of atoms of each element must be the same on both sides of a chemical equation.

Reactants

starting materials

Products

result of reaction

All chemical reactions have a conservation of…

• mass

• charge

• energy

What are the 7 diatomic molecules?

• H₂

• N₂

• O₂

• F₂

• Cl₂

• Br₂

• I₂

Combustion Reaction

Hydrocarbon + oxygen → carbon dioxide + water

Synthesis Reaction

A + X → AX

Decomposition Reactions

AX → A + X

Single Displacement Reaction

AX + B → BX + A

Double Displacement Reaction

AX + BY → BX + AY

Neutralization Reaction

Acid + Base → Salt + Water

Activity Series

List of elements in order of their tendency to react

Activity Series Rules

If the unbonded element in front is less reactive then the bonded element (the one it is trying to replace), the reaction will not happen.

Boyle’s Law

When temperature is constant, pressure and volume are inversely related

Charles’ Law

When pressure is constant, volume and temperature are directly related

Gay-Lussac’s Law

At constant volume, pressure and temperature are directly related