MCAT General Chemistry

Formal Charge Equation

Valence electron - 0.5 bonding electrons (sticks) - free electrons (dots)

Molecular Geometry: 2 groups represent what

sp - Linear

Molecular Geometry: 3 groups represent what

sp2 - Trigonal planar

Molecular Geometry: 4 groups represent what

sp3 - Tetrahedral

What are the INTRAmolecular forces

Ionic bonds, Covalent bonds, Metallic Bond, Coordinate Covalent Bond

INTRAmolecular forces: The longer the distance between atoms and less electrons shared

The weaker the bond

Breaking a bond is what kind if process?

Endothermic

Ionic Bond

Bond between particles of opposite charges. Transfer of Electrons

Ionic bonds in aqueous solutions

Will separate; electrolytes

Covalent Bond

Formed between atoms of opposite charge with high electronegativity. Share electrons

Metallic Bond

Bond between metals. Atoms with low electronegativity

Coordinate Covalent Bond

Donate both electrons to bond

What are the INTERmolecular forces?

Ion-Dipole force, Dipole-Dipole, Dispersion Forces and Hydrogen Bonding

INTERmolecular forces: The larger the charge

The stronger the bond

INTERmolecular forces: The smaller the charge

The weaker the bond

Ion-Dipole force

Ion bonds with polar molecule. Molecule will orient to the opposite charge to bond

The larger the ionic charge & dipole

The larger the force

Dipole - Dipole

Bond between two polar molecule

The more polar the molecule in dipole - dipole

The stronger the force generated

Dipole Induced Dipole

Bond between a polar and non-polar molecule

London Dispersion

Bond between any and all molecules

Hydrogen Bonding

Bonding with very polar molecules. Nitrogen, Oxygen or Fluorine

Enthalpy

Energy stored

Forming a bond is what kind if process?

Exothermic

Reactants being higher than products in regards to enthalpy is what?

Exothermic

Reactants being lower than products in regards to enthalpy is what?

Endothermic

Entropy

Potential randomness

How can you alter randomness?

Increasing volume, Increasing temperature, increasing the amount

Gibbs Free Energy

Measure of if there is enough energy available to do work in chemical process

In Gibbs Free Energy: Reactants higher than products is what?

Spontaneous, Exergonic

Delta G is what in a spontaneous, exergonic process?

Negative

Delta G is what in a non-spontaneous, endergonic process?

Positive

In Gibbs Free Energy: Reactants lower than products is what?

Non-spontaneous, Endergonic

Gibbs Free Energy Equation

The stronger the IMF

The stronger the phase of matter

Phases of matter from High to Low IMF

Solids > Liquids > Gases > Ideal Gases

Gas to liquid is

Condensation

Liquid to Solid is

Freezing

Solid to Liquid is

Melting

Liquid to Gas is

Boiling (Vapor)

Solid to Gas is

Sublimation

Gas to Solid is

Deposition

When Heat is absorbed

Kinetic Energy and Entropy increases

When Heat is released

Kinetic Energy and Entropy decreases

Heat of Fusion Equation

q = n * delta H

Specific Heat Equation

IMF are __ proportional to Volume

Indirectly

IMF are __ proportional to Pressure

Indirectly

External Pressure and IMF are __ proportional to Density

Directly

External Temperature is ___ proportional to Density

Indirectly

External Temperature is ___ proportional to Vapor Pressure

Directly

IMF is __ to Vapor Pressure

Indirectly

What effect does external pressure have on Vapor Pressue?

No effect

External Pressure and IMF are __ proportional to boiling point

Directly

External Pressure and IMF are __ proportional to melting/freezing point

Directly

Solution

Homogenous mixture of 2 or more substances

In terms of solute: A strong electrolyte

Breaks apart completely

In terms of solute: A weak electrolyte

Breaks apart “sort of”

In terms of solute: A non-electrolyte

Doesn’t break at all

Van’t Hoff Factor (i)

The number of particles electrolytes break into.

Solubility

Amount of something that can dissolve at certain temperatures

Unsaturated

Concentration of Solute is less than solvent

Saturated

Concentration of Solute is equal to solvent

Supersaturated

Concentration of Solute is greater than solvent

Solid & Liquid solubility is directly proportional to

Temperature

Gaseous solubility is directly proportional to __, and indirectly proportional to

Temperature, Pressure

Boyles Law

Pressure is inversely proportional to Volume V α 1/P

Charles Law

Temperature is directly proportional to volume V α T

Amonton’s Law

Temperature is directly proportional to Pressure P α T

Combined Gas Law

Ideal Gas Law

Mole Fraction

Dalton’s Law

Grahm’s Law

What determines Delta H & Delta G

Difference of reactant energy and product energy

What is Activation Energy (E_a)

The difference between reactant energy and highest energy transition state.

Rate determining step

Highest peak, also the slowest

Rate Law Equation

How is a reaction in equilibrium?

When the forward and reverse rates are equal

K > 1

In equilibrium products are favored

K = 1

In equilibrium neither are favored

K < 1

In equilibrium reactants are favored

What does the Reaction Quotient (Q) describe?

The distance from equilibrium

Q > K

Too much product, shifts toward reactants

Q = K

In equilibrium

Q < K

Too much reactant, shifts toward products

What is a Brønsted Acid

Donate a proton

What is a Brønsted Base

Accepts a proton

What is a Lewis Acid

Accepts electron pairs, acts as an electrophile

What is a Lewis Base

Donates electron pairs, acts as an nucleophile. Are ligands and chelates

What are some characteristics of acids?

They usually have a more electronegative atom bonded to H. They can have large positive charge.

What are some characteristics of a base?

They usually have less electronegative atoms with lone pairs.

What is an Amphoteric Compound?

Compound with both characteristics of acids and bases

General rules for identifying an acid?

More positive charge, High in electronegativity, large atomic size

General rules for identifying a base?

More negative charge, low electronegativity, small atomic size

What are the strong acids?

H₂SO_4, HClO_4, HClO_3, HNO_3, HCl, HBr, HI

What are the strong bases?

O^2- , OH^-, OR^- , NH₂^- ,NR₂^-, H^- ,R^-

Characteristics of Strong Acids

Dissociate completely, Ka > 1, produces weak conjugate base. Products are favored in equilibrium

Characteristics of Weak Acids

Dissociate partially, Ka < 1, equilibrium favors the reactants. Produces strong conjugate bases

Characteristics of Strong Bases

Dissociate completely, Ka > 1, produces weak conjugate acids, equilibrium favors products