CHEM 0110: Exam 2
50 Cards in this Set
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Density Formula
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d= (p*MM)/RT
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Gas Laws
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p1V1=p2V2
p1/T1=p2/T2
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total pressure
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sum of all partial pressures
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Calculating ΔH
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final energy-initial
exo: ΔH of the system is negative
endo: ΔH of the system is positive
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Breaking Bonds is....
Forming Bonds is...
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breaking: endothermic
forming: exothermic
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Exothermic Reactions
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combination (can be endo), single displacement, combustion
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Endothermic Reactions
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decomposition (can be exo), vaporization, melting
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What is ΔH?
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heat transferred when the reaction is carried out under conditions of constant pressure
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specific heat of water
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4.18 J/gCelsius
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q always refers to what?
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the surroundings
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relationship between wavelength and frequency if c is constant
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inversely proportional
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wavelength for:
red light
blue light
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red: 700nm
blue: 400 nm
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photon
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smallest unit of light energy
energy of photon=hv
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Visible Light
(Infrared to UV)
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wavelength decreases
frequency increases
Ephoton increases
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When light is absorbed by matter...
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individual atoms or molecules absorb 1 photon at a time
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3 Labels to characterize an orbital
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n, l, ml
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n
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quantum number
determines energy and size of orbital
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l
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quantum number
defines overall shape of electron cloud
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ml
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quantum number
defines orientation of the orbital
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Differences between H and other atom
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energies of orbitals decrease as protons added
energies depend on n and l
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Magnetic properties
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you have to have one or more unpaired electron
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paramagnetic
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with one or more unpaired electron and it's magnetic
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diamagnetic
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with no unpaired electron
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Exceptions to electron configuration
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Cu, Ag, Au, Cr
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Ionization Energy
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-energy needed to remove highest energy electron from the atom
-ranges from 400 - 2400 kJ/mol
-always an endothermic process
-increases as you move up and to the right of periodic table
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Electron Affinity
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-energy needed to add an electron to an atom
-often exothermic
-halogens have most exothermic EA
-noble gases have endothermic values
-small compared to IE
-ranges from 350 to -50 kJ/mol
-increases as you move up and to the right to the periodic table
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Atomic Size
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related to size of the largest valence orbital of the atom
large orbital=large atomic size=small IE
small orbital=small atomic size=large IE
increases as you move down and to the left of the periodic table
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Electronegativity
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ability of an atom to attract an electron to it from another atom to which it is bonded
-increases as you move up and to the right to periodic table
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Large and Small EN
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Large: high electron attracting power
-active non-metals
Small: low electron attracting power
-active metals
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EN: 0.7-1.5
2.5-4.0
2.0
2.1
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0.7-1.5: fairly active metal
2.5-4.0: fairly active non-metal
2.0: metalloids
2.1: hydrogen
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Exceeds Octet rule
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3rd and 4th period
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-ane
-ene
-yne
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-ane: single bond
-ene: double bond
-yne: triple bond
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Bond length and dissociation energy
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bond length decreases from single to triple
dissociation energy increases from single to triple
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Exceptions to Octet Rule
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-species with odd number of electrons
-elements beyond 2nd period
-electron deficient species
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1 atm=
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76cmHg = 760 mmHg
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Atmospheric pressure and altitude
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pressure decreases when altitude increases
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at constant n and T: p and V are...
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inversely proportional
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at constant n and V: p and T are...
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directly proportional
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molecular speed increases with... and decreases with...
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temperature and increasing mass
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Hess's Law
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No matter how many steps you go through to get a reaction, the enthalpy change is always the same
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Boyle's Law
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pressure and volume are inversely related when at a given temperature
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Kinetic Theory of Ideal Gas
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1. Molecules spread out in space so separation > molecular size
2. Molecules moving rapidly
3. Pressure due to molecules bouncing off walls of container
4. Gas molecules collide and are elastic
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mole fraction
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Xa= (Na/Ntotal)=(Pa/Ptotal)
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Hund's Rule
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In a set of orbitals with the same energy, electrons tend to occupy different orbitals with the same spin.
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paulie exclusion principle
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states that a max of 2 electrons can occupy a sungle orbital , but only if the electrons have opposite spins
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Gas Laws in General:
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(P1*V1)/(n1/T1)=(P2*V2)/(n2/T2)
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Rules for determining delta H from bond energies
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bonds broken-bonds formed
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y2
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y2 is the probability of finding the electron in a small volume at a distance r from the nucleus
-part of Schrodinger equation
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Diamagnetic
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all spins are paired, not attracted to a magnetic field
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paramagnetic
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unpaired spins, attracted to a magnetic field
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CHEM 0110: Exam 2