Chemistry Flashcards
Electron Configuration (Periodic Table)
S,P,D,F
Polar Covalent Bond
Bonding electron pair is not equally shared.
Pull toward more electronegative atom
Geometry of molecules
Regions of electron density 2=linear, 180 3=bent,120 4=tetrahedral,109.5 5=trigonal bipyrimidal, 90,120,180 6=octahedral, 90,180
Intermolecular Forces
Hydrogen bonding
Dipole-Dipole Interactions
Dispersion Forces
Hydrogen Bonding
The partial positive charge of hydrogen atom interacts with partial negative charge located on electronegative atoms (F,O,N) of nearby molecules
Dipole-Dipole
Polar molecules orient themselves so that the positive region of one molecule is close to the negative region of another molecule
Isothermal Process
Temperature of system remains constant
Adiabatic Process
No heat exchange occurs
Isobaric Process
Pressure of system remains constant
Isovolumetric(Isochoric)
Volume remains constant
Heat
Transfer of thermal energy from one object to another
Endothermic
Reactions that absorb thermal energy
Exothermic
Reactions that release thermal energy
Enthalpy (H)
Used to express heat changes at constant pressure
Standard heat of formation
Delta Hf
The enthalpy change that would occur if one mole of a compound was formed directly from its elements in their standard states
Standard heat of reaction
Delta Hrxn
Hypothetical enthalpy change that would occur if the reaction were carried out under standard conditions
=Sum of Delta Hf of products - Sum of Delta Hf reactants
Hess’s Law
Enthalpies of reactions are additive
Reverse of any reaction has an enthalpy of same magnitude as forward reaction, but with opposite sign
Bond Dissociation Energy
Average of the energy required to break a particular type of bond in one mole of gaseous molecules
Bond Enthalpy
Standard heat of reaction can be calculated using bond dissociation energies of particular bonds (given from table)
Delta Hrxn= Sum Delta H bonds broken - Sum Delta H bonds formed
Entropy (S)
Measure of distribution of energy throughout a system
Delta S= Delta Ssystem + Delta Ssurroundings
Gibbs Free Energy (G)
Combines 2 factors that affect the spontaneity of a reaction. Changes in enthalpy and entropy
Detla G= Delta H-T Delta S
If G is negative the reaction is
Spontaneous
If G is positive the reaction is
Non-Spontaneous
If G=0 the reaction is
At equilibrium and Delta H=T delta S
At a moderately high pressure a gasses volume is…
less than would be predicted by ideal gas law due to intermolecular attraction
Boyles Law
k=PV or P1V1=P2V2
Charles Law
k=V/T or V1/T1=V2/T2
Gay-Lussac;s Law
k=P/T or P1/T1=P2/T2
Combined Gas Law
P1V1/T1=P2V2/T2
Ideal gas law
PV=nRT
Arrhenius Definition
An acid is a species that produces excess H+ in an aqueous solution and a base is a species that produces extra OH-
Bronsted Lowry Definition
An acid is a species that donates protons while a base is a species that accepts protons
Lewis Definition
An acid is an electron pair acceptor and a base is an electron pair donor
pH=?
pH=-log[H] = log(1/[H+]
pOH=?
pOH=-log[OH] = log(1/[OH-])
Kw=?
Kw=[H+][OH-] = 10^-14
pH+pOH=?
pH+pOH= 14
Ka=?
[H3O+][A-]/[HA]
Kb=?
[B+][OH-]/[BOH]
Salt Formation
Acids and bases may react with each other, forming a salt and often water in a neutralization reaction
HA+BOH—>BA+H2O
Hydrolysis
The reverse reaction where salt ions react with water to give back the acid and the base
Amphoteric Species
One that can act either as an acid or base depending on its chemical environment
Henderson-Hasselback Equation
pH=pKa+log[conjugate base]/[weak acid]
pOH=pKb+log[conjugate acid]/[weak base]
Oxidation
Loss of electrons
Fewer Bonds to Hydrogen
More bonds to heteroatoms (O,N, halogens)
Typically goes from OH to O
Reduction
Gain of electrons
More Bonds to Hydrogen
Fewer bonds to heteroatoms
Typically goes from O to OH
Oxidizing Agent
Causes another atom to undergo oxidation and is itself reduced
High affinity for electrons (O2, O3, Cl2)
Reducing Agent
Causes another atom to be reduce and is itself oxidized
Good reducing agents include sodium, magnesium, aluminum, and zinc
Low electronegativities and ionization energies
Gibbs free energy in electrolytic cells
Delta G= -nFEcell
Ecell=electromotive force
Nucleophile
Nucleus Loving
Tend to have lone pairs or pi bonds that can form new bonds to electrophile
Electrophile
Electron Loving
Tend to have a positive charge or positively polarized atom that accepts an electron pair form a nucleophile
Enantiomers
Non-superimposible mirror images
Have opposite stereochemistry at every chiral carbon
Same chemical and physical properties
Diastereomers
Non mirror image stereoisomers
Have different chemical and physical properties
Thin Layer Chromatography (Use, Mobile and Stationary Phase)
Identify a sample
Mobile Phase: Nonpolar solvent
Stationary Phase: Polar solvent
Reverse Pahse (Use, Mobile and Stationary)
Identify a sample
Mobile Phase: Polar solvent
Stationary Phase: Nonpolar solvent
Column Chromatography
Separates a sample into components
Mobile: Nonpolar solvent
Stationary: Polar gel or powder
Ion Exchange Chromatography
Separates components by charge
Mobile: Nonpolar solvent
Stationary: Charged beads in column
Size Exclusion Chromatography
Separate Components by size
Mobile: Nonpolar solvent
Stationary: Polar, porous beads in column
Affinity Column
Purify a molecule of interest
Mobile: Nonpolar solvent
Stationary: Bead coated with antibody or receptor for target molecule
Gas Chromatography
Separate vaporizable compounds
Mobile: Inert Gas
Stationary: Crushed metal or polymer
High Performance liquid chromatography (HPLC)
Similar to column but more precise
Mobile: Nonpolar solvent
Stationary: Small column with concentration gradient
IR Spectroscopy
Measures Molecular vibrations of characteristic functional groups
Power equation
P=W/delta t
Work/ change in time
Total Mechanical Energy equation
E=U+K
potential energy+kinetic energy
Power by resistors
P=IV
V^2/R
I^2R
Conjugate Acid
Formed when a proton is added to a base
H20–>H3O
Conjugate Base
Formed when a proton is removed from an acid
H2PO4–>HPO4
