Chemistry Chapters 7, 8, 9

Collision Theory

A set of statements that give the conditions necessary for a chemical reaction to occur

Molecular Collisions

Reactant particles must interact (collide) with one another before any reaction can occur

Activation Energy

Colliding particles must posses a certain minimum total amount of energy, for a reaction to occur

Collision Orientation

Colliding particles must come together in proper orientation unless particles involved are single atoms, or small symmetrical molecules

Exothermic Reaction

• Energy is released

• Products are lower energy than reactants

• E_reaction = E_product Minus E_reactant

Endothermic Reaction

• Energy is absorbed

• Products are higher in energy than reactants

• E_reaction = E_product Minus E_reactant

Eq =

E_{activated complex} Minus E_reactant

The higher the activation energy

The slower the reaction

If products are lower in energy than reactants

E_reaction or Triangle H is negative = Exothermic

If reactants are lower in energy than products

E_reaction or Triangle H is positive = Endothermic

Factors that Influence Chemical Reaction Rates

• The physical nature of the reactant (more space for molecules to move = faster reaction)

• Reactant Concentrations (Higher concentration = More reactants)

• Reaction Temperature (Temperature increase = reaction rate increase)

• Presence of a Catalyst

Catalyst

A substance that increases a chemical reaction rate by lowering activation energy

Hyperthermia

An uncontrolled increase in body temperature due to the body inability to lose all of the extra internal heat energy

Hypothermia

An uncontrolled decrease in body temperature due to the body inability to generate enough thermal energy

Reaction Rate

The speed of a chemical reaction

The rate of a reaction

A measure of how fast the reaction makes products or uses reactants

The rate of a chemical reaction

Measures how much concentration of a reactant decreases, or product concentration increases

Rate =

-/+1/a (Triangle [A] / Triangle t); - sign goes in front of reactants, and + goes in front of products

Rate Law

A reaction that shows a mathematical relationship between the rate of an reaction and concentrations of the reactants and homogenous catalysts. Ex. Rate = K[A]^m[B]ⁿ

Reversible reaction

A reaction that can be made to go in either direction

Equilibrium

• A dynamic state in which the rate of the foward reaction is equal to the rate of the reverse reaction

• No change in concentration of either reactants or products

• The two reactions are equal

K_equilibrium =

Products / Reactants

Factors that influence chemical equilibrium:

• Temperature (Initial amount of reactants or products does not effect K_eq, if temp doesn’t change)

• Equilibrium constant values and reaction completeness

If concentration of a reactant/product is increased

shift to the opposite side to use up some of it

If concentration of a reactant/product is decreased

shift to the same side to make more of it

When heat is a reactant

The reaction is Endothermic

When heat is a product

The reaction is Exothermic

If pressure decreases

Shift in the direction of more moles of gas

If pressure increase

Shift in the direction of less moles

HCl

Hydrochloric acid

HBr

Hydrobromic acid

HI

Hydroiodic acid

HNO₃

Nitric acid

H₂SO₄

Sulfuric acid

HClO₄

Perchloric acid

HClO₃

Chloric acid

LiOH

Lithium hydroxide

NaOH

Sodium hydroxide

KOH

Potassium hydroxide

Ba(OH)₂

Barium hydroxide

Ca(OH)₂

Calcium hydroxide

Sr(OH)₂

Strontium hydroxide

RbOH

Rubidium hydroxide

C_sOH

Caesium hydroxide

The “strength” of an acid or a base is a measurement of

the extent to which it reacts/dissociates or protonates in water

An acid or a base is said to be strong when

it dissociates completely in solution. (K > >1)

When strong acids or bases go in a foward direction

The K is very large

When weak acids or bases go thorugh equilibrium/double arrow

The K is very small

Bronsted Lowry

• Acids: Increase the concentration of [H₃0⁺] or [H⁺] in water

• Bases: Increase the concentration of [OH^-] in water

Arrhenius

• Acids: Proton (H⁺) donors

• Bases: Proton (H⁺) acceptors

Lewis

• Acids: Electron Acceptors

• Bases: Electron donors

Acid ionization constant (K_a)

It’s the equilibrium constant for the reaction of a weak acid with water

Ex. HA_(aq) + H₂O_(l) ⇌ A^-_(aq) + H₃O_(aq)

Base ionization constant

It’s the equilibrium constant for the reaction of a weak base with water

Ex. A^-_(aq) + H₂O_(l) ↔ OH^-_(aq) + HA_(aq)

K_a =

[H₃O⁺] [A^-] / [HA]

K_b =

[OH-] [HA] / [A-]

Monoprotic

An Acid that only has 1 acidic proton

Ex. HCl, HI, HNO₃

Diprotic

An acid that has 2 acidic protons

Ex. H₂SO₄, H₂CO₃

Triprotic

An acid that has 3 acidic protons

Ex. H₃PO₄

The conjugate acid has one more proton (H⁺) than

the conjugate base

When looking at both conjugate acids and bases, the more positive one is

The acid

Water is amphiprotic, meaning

it can act either as an acid or a base depending on what it’s being mixed with

If an Anion ended with “ide”

Ex. chloride, Cl^-

Adding H⁺ ions turns it into hydro___ic acid

Ex. hydrochloric acid, HCl

If an Anion ended with “ate”

Ex. chlorate, ClO₃^-

Adding H⁺ ions turns it into ____ic acid

Ex. Chloric acid, HClO₃

If an Anion ended with “ite”

Ex. chlorite, ClO₂^-

Adding H⁺ ions turns it into ____ous acid

Ex. Chlorous acid, HClO₂

Binary Acids

Contain hydrogen and a monoatomic anion

Ex. Anion: Cl^- (chloride) Corresponding Acid: HCl (hydrochloric acid)

Oxoacids

Contain hydrogen and a polyatomic oxyanion

Ex. Anion: ClO₄^- (perchlorate) Corresponding Acid: HClO₄ (perchloric acid)

NO₃^-

Nitrate ion

ClO₃^-

Chlorate ion

CO₃^2-

Carbonate ion

SO₄^2-

Sulfate ion

PO₄^3-

Phosphate ion

CH₃COO^-

Acetate ion

OH^-

Oxide ion

CN^-

Cyanide ion

pH =

-log [H₃O⁺]

Adicic solution

One whose pH is less than 7.0

Basic solution

One whose pH is more than 7.0

Neutral solution

One whose pH is equal to 7.0

In pure water, [H₃O⁺] and [OH^-] =

1.0 × 10^-7 mol/L

Buffer Solution

It’s something that resists changes in pH when small quantities of an acid or an alkali are added to it

A buffer solution

can be a (aq) solution made from a weak acid and it’s conjugate base, or a weak base and it’s conjugate acid

Normal blood pH level

7.35 to 7.45

Hydrogen carbonate buffer is

the most important buffer in blood

Acidosis

Blood pH levels between 7 and 7.34

Alkalosis

Blood pH levels between 7.46 to 7.8

Indicator

An organic solvent that changes color when a solution changes from acidic to basic or visa versa

Equivalance point

Moles of added acid = Moles of base in flask

Acid-base titration requirements

1. We must know the equation for the reaction so that we can determine the stoichiometric ratio of reactants to use in our calculations

2. The reaction must be rapid and complete

3. There must be clear-cut change in a measurable property at the equivalence point (when the reagents have combined exactly)

4. We must have accurate measurements of the amount of each reactant

Henri Becquerel determined that

1. All the minerals that produced these rays contained uranium

2. The rays were produced even though the mineral was not exposed to outside energy

3. He called them uranic rays because they were emitted from minerals that contained uranium (Like X-rays and not related to phosphorescence)

What did Marie Curie determine?

She determined that rays were emitted from specific elements

Marie Curie discovered new elements by detecting their rays

• Radium named for its green phosphorescence

• Polonium named for her homeland (Poland)

Because these rays were no longer just a property of uranium, she renamed it radioactivity

Three-fourths of all exposure to radiation comes from what?

Background radiation

Most of the remaining one-fourth comes from medical irradiation such as what?

X-rays

What is Ionizing radiation?

It’s when nuclear radiation is capable of removing electrions from molecules to from ions in cells

What can ionizing radiation disrupt?

It can disrupt DNA, causing mutations

What are free radicals?

They are molecules that can splinter into neutral fragments

What can free radicals disrupt?

They disrupt cellular processes

Radiation often affects the fastest growing cells and tissues such as what?

• White blood cells

• Bone marrow

Nucleons (protons and neutrons) equals

Mass number

Mass number equals

Protons + Neutrons