MCAT Chemistry

Keq

Ratio representing the concentrations of products over reactants in a reversible reaction

ΔG=ΔH-TΔS

Gibbs free energy in a system

ΔG

Gibbs free energy. If negative reaction is spontaneous. if positive reaction is nonspontaneous.

ΔH

Enthalpy. Shows a change in heat

ΔS

Entropy. Shows a change in chaos

Lewis acid

takes electrons

Arrhenius base

gives OH-

Bronsted Lowry Acid

gives hydrogen

Bronsted Lowry Base

takes hydrogen

Why is ammonia a gas but ammonium is not

Ammonium’s positive charge allows it to interact with water which prevents it from being gaseous

In a spontaneous reaction, do reactants or products have larger ΔG?

Reactants

Are spontaneous reactions exergonic or endergonic

exergonic

In a spontaneous reaction, do reactants or products have lower activation energy?

reactants

ΔG=-RT ln(Keq)

Free energy in standard conditions

ΔG=-RT ln(Q/Keq)

Free energy in non standard conditions

Coordinate covalent

bond where 2 electrons in the bond come from the same atom

Polar covalent bond

bond where the two bonding atoms have very different electronegativities

What is the electron configuration of silver

1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s¹4d¹⁰

What does the principle quantum number, n, show

The highest energy level of a atom

Arrhenius acid

gives H+

pKw=pH + pOH

pk of water equation

What are the pH and pOH values in water

They are equal

pH=-log[H⁺]/pOH= -long[OH^-]

pH and pOH equations

As Ka increases, what happens to acid strength

It increases

When in salt forms, how is Ka determined

Stronger conjugate bases have weaker acids and smaller Ka’s

Ka= [X-][H+]/[XH]

Disassociation constant equation

What does a buffering zone look like in a titration

Each Ka in a compound will create a buffering zone which has a flat area followed by a sharp drop or rise

Ideal gas equation

PV=nRT

What does a catalyst do?

Affects the activation energy of a reaction by lowering it

First order kinetics

Depends on one reactant

Second order kinetics

depends on two reactants

Third order kinetics

depends on 3 reactants

Is the slow or fast step rate determining

Slow step

Gibbs free energy with R

ΔG=-RTlnKeq

How to calculate oxidation numbers

Based on electronegativity of bonded atoms, electrons will move away or toward the atom of interest. Losing electrons increases oxidation and vice versa

What is a colloid

A heterogenous mixture

What is a electrolytic solution

A solution where a compound dissociates

How must H and OH relate for neutralization to occur

moles of H a nd moles of OH must be equal

What is fractional distillation

A method to separate liquids where a mixture is heated up till the liquids evaporate at their different boiling points

Titration equation

V_aN_a=V_bN_b. Where V is volume of acid/base and N is number of protons donated/accepted

What is a reducing agent

Molecule that is oxidized

What is a oxidizing agent

Molecule that is reduced

How does acid acidity relate to conjugate base stability

A very acidic acid will produce a stable conjugate base