Physics and Chem II (SIMPLE EDITOR) Flashcards
When calculating the density of a volatile liquid, must take what into account
some will evaporate – so will lose mass
Mass % of a solute * Density =
(Mass Solute/Mass Soln)*(Mass Soln/Vol Soln) = Mass Solute/Vol Soln
How to convert from grams or moles of a gas to get to liters of an ideal gas at STP?
22.4 Liters of gas / 1 mol gas(so would need to convert grams of gas to mols first if given grams)
Molecular Formula vs Empirical Formula
Molecular Formula is the actual mole ratio of the elements within the compound.Empirical Formula uses the smallest whole number ratio of the atoms in each compound.
How to calculate empirical formula
Assume 100–gram sample so the percentages can easily be changed into mass figuresthen convert mass into moles (using atomic masses of each element)the empirical formula is then the whole number ratio of these mol values
How to convert between molecular and empirical formulas
Multiply the empirical formula by the whole number ratio of the molecular mass to the empirical mass
What is a combustion reaction?
Hydrocarbon + Excess Oxygen ––––combusted–––> Carbon Dioxide + Water VaporCxHy + O2 –––> CO2 + H2O(Hydrocarbon is oxidized)
Molality (m)
Moles Solute / Mass Solvent (kg)
Which of the following are affected by temperature changes?MolarityMolalityMass Percent”
Molarity = IS affectedMolality = IS NOT affectedMass Percent = IS NOT affected
Mass Percent (in soln)
Mass Solute / Mass Solution *100%
Trick for calculating dilution
Recognize that total moles of a solute remain constant when a solvent is added, so M*V remains constant:MiVi = MfVf
What is a simple dilution?
Addition of pure solvent
What is Beer’s Law?–idea behind it–equation for it–trick for solving problems
States that you can pass electromagnetic radiation through a solution and the solution may absorb some of the light – the light absorbed will be a specific wavelength range and the absorbance intensity will vary directly with the concentration of the solute:
What is Beer’s Law?–equation for it
Abs = εClwhere ε = a constant for the soln at λmax C = [solute] l = width of cuvette (length of pathway through which light passes)
What is Beer’s Law?–trick for solving problems
Absi * Vi = Absf*Vf
the limiting reagent is the reactant with _______________
the lowest ratio of actual moles to needed moles
What are the solubility rules?
(1) Most salts containing alkali metal cations (Li+, Na+, K+, Cs+, Rb+) and Ammonium (NH4+) are water soluble(2) Most nitrate (NO3–) salts are water–soluble(3) Most salts containing halide ions (Cl–, Br–, I–) are water–soluble (except with heave metals such as Ag+ and Pb2+)(4) Most salts containing Sulfate anions (SO42–) are water–soluble(5) Most hydroxide anion (OH–) salts are only slightly water–soluble. (KOH ad NaOH are substantially soluble, while Ca(OH)2, Sr(OH)2, and Ba(OH)2 are fairly soluble)(6) Most carbonate anion (CO32–), chromate anion (CrO42–), phosphate anion (PO43–), and sulfide anions (S2–) salts are only slightly water–soluble
CaCO3 is a(n) ____________
BASE
In composition reactions, what is happening (and how is entropy affected)
Reactants combining to form a product:More bonds formed, so entropy decreases
In decomposition reactions,what is happening (and how is entropy affected)
Reactants decompose to form multiple products:More bonds broken = entropy increases
Which atom (or compound) is the reducing agent (reductant) and which is the oxidizing agent (oxidant)
Atoms losing electrons = reducing agent (reductant)Atoms gaining electrons = oxidizing agent (oxidant)
Loss of Electrons in a reaction = a(n) _______Gain of Electrons in a reaction = a(n) ______
Loss of Electrons = OxidationGain of Electrons = ReductionLEO the lion goes GER
In combustion reaction, oxygen serves as the _______
oxidizing agent
Oxidation state of an atom an be determined by ________
looking at bonds it forms with less electronegative atoms (gives it a –1 for every bond) and bonds it forms with more electronegative atoms (gives it a +1 for every bond)
general rules for assigning oxidation states
O = –2 (except in molecular oxygen and peroxides)H = +2 (except in molecular hydrogen and hydrides)Halides = –1 (except when they are a central atom in an oxyacid)
1/5
0.2
1/6
0.1166
1/7
0.143
1/8
0.125
1/9
0.111
1/11
0.091
1/12
0.083
conduction vs convection
conduction = transfer of heat through direct contactconvection = transfer of heat through a liquid or gas medium
sublimation
solid –––––> gas
giga =
10^9
mega =
10^6
deci =
10^ –1
centi =
10^ –2
milli =
10^ –3
micron =
1 micron = 10^ –6 meters
Angstrom =
1 Angstrom = 10^ –10 meters
pico =
10^ –12
fempto =
10^ –12
calorie to joule conversion
1 calorie = 4.18 Joules
kilogram to pound conversion
1 kg = 2.2 pounds (on earth)
liter to meter conversion
1000 liters = 1 cubic meter
Mile to meter conversion
1 mile = roughly 1600 meters
foot to meter conversion
1 meter is a little over 3 feet
inch to cm conversion
1 inch = roughly 2.5 cm
Important Trig function to remember
cos^2(theta) + sin^2(theta) = 1
cos 0 =
1
cos 30 =
sqrt(3) / 2 = 0.86
cos 45 =
sqrt(2) / 2=0.71
cos 60 =
1/2 =0.50
cos 90 =
0
sin0 =
0
sin 30 =
1/2=0.50
sin 45 =
sqrt(2) / 2=0.71
sin 60 =
sqrt(3) / 2=0.86
sin 90 =
1
tan =
sin/cos=opp/adj
What is the kinematic equation to use when:you don’t have Vfinal?(assume all are in x direction)
Δx = viΔt + 1/2 a(Δt)^2
What is the kinematic equation to use when: you don’t have dx(displacement of x)? (assume all are in x direction)
vf = vi + a(Δt)
What is the kinematic equation to use when: you don’t have a? (assume all are in x direction)
Δx = (1/2)(vi + vf)Δt
What is the kinematic equation to use when: you don’t have t? (assume all are in x direction)
(vf)^2 =(vi)^2 + 2aΔx
Without air resistance, a ball will fall _____ meters in 1 second, _____ meters in 2 seconds, and so forth (_______)
Will fall 5 meters in 1 second and 20 meters in 2 seconds (and 80 meters in 4 seconds) Δy = 5t^2*assuming starts with zero velocity
Estimate (disregarding air resistance) the velocity of a ball falling after 1 second, 2 seconds, etc.
Velocity = 10Δt*assuming starts with zero velocityso after 1 second, v = 10 m/s2 seconds, v = 20 m/s3 seconds, v = 30 m/sand so on
Calculate how much time (disregarding air resistance) it will take a ball to reach the top given an initial velocity
Δt = vi / 10
Throwing a projectile: Calculate the height the projectile travels
h = (viy)^2 / 10or (viy)^2 /g
Throwing a projectile: Calculate the time it takes the projectile to reach the top
t = viy / 10or t = viy / g
Calculate the range of a projectile
r = 2voxvoy / gr = (vo)^2 sin2Θ / g
When does a projectile have maximum range? What is the formula for its range in that case?
when Θ = 45 degreesr = (vo)^2 sin(90) / g = (vo)^2 / g
What is the relationship between r and f at given thetas (from the horizontal):30 degrees45 degrees60 degrees”
30 degrees:r/h = 6.745 degrees:r/h = 460 degrees:r/h = 2.4
Static friction vs kinetic friction
Static = when there is no sliding (keeps object at rest; also can accelerate an object from rest) Kinetic = when there is sliding (slows object down)
Calculating Torque
T = rFsin(theta)
or
T = rF(perpendicular)
Calculating mechanical advantage of a system
= Weight of object / Applied force needed to support object
What is the Normal force of an object on an inclined plane (with horizontal angle theta)
F = mgscos(theta)
What is the acceleration of an object down an inclined plane (With horizontal angle theta, and no friction)
a = gsin(theta)
Relate distance traveled to acceleration and time
x = vit + (1/2)a*(t^2)
An object is moving in a circle at a constant speed, what is the net Force experienced by the object?
Towards the center of the circle
An object turns without changing speed, what is the net force applied to the object?
Net force is perpendicular to the object’s motion
Calculate the Static Friction Force
F(max static friction) = (mu)N
- Where mu = the static friction coefficient
- N = Normal Force on an inclined plane = mgcos(theta)
Calculate Force of a Spring
F = kx
- where k is the spring constant (N/m)
- x is the displacement of the string
How does static friction relate to an applied force?
It is a REACTIONARY force –> so it is equal and opposite to applied force
Calculate mechanical advantage for a pulley system
-Use mechanical advantage to determine the amount of force needed to lift an object (with Weight W Newtons)
MA = (# pulleys)*(sin(theta))
Force needed = W / MA
Coloumb’s Law:
Relates the magnitude of force to the distance between two charges:
F = kq(1)q(2) / (r^2)
*so, if you triple the distance, the strength of the electric field is 1/9th
**can modify for the strength of an electric field around a point charge: E = kq / (r^2)
Units for electric field strength
N/C —or—- V/m
Calculate change in voltage given for a point charge that moved in an electric field
Delta(V) = E * d(parallel or antiparallel)
*where E = electric field strength (N/m) and d(parallel or antiparallel) = distance traveled that is parallel or antiparallel to the electric field
When will a point charge experience a voltage change in an electric field?
Only when moving parallel or antiparallel to the electric field
Calculate the work done by an electric field on a point charge
W = delta(V) * q
Where delta(V) = the change in voltage and q = charge on the point charge
An electric field points towards _____ charge.
So a positive charge will move in the same/opposite direction of the electric field lines?
Points towards NEGATIVE.
___________
Positive charge will more SAME direction as the electric field (e.g., in the direction of +E; the same direction the electric field lines point)
Calculate the Force on a point charge in an electric field
F = Eq
*where E = Electric Field, and q = charge on the point charge
Calculate the energy of a photon
E = hf = hc/(lamda)
*where lamda = the wavelength of the photon
sp hybridization = what geometry and bond angle
linear; 180 degrees
sp2 hybridization = what geometry and bond angle
– and what possible molecular shapes given the # of lone pairs
trigonal planar; 120 degrees
- -shapes:
- 0 lone pairs = trigonal planar
- 1 lone pair = bent
sp3 hybridization = what geometry and bond angle
– and what possible molecular shapes given the # of lone pairs
tetrahedral; 109.5 degrees
- -shapes:
- 0 lone pairs = tetrahedral
- 1 lone pair = trigonal pyramidal
- 2 lone pairs = bent
sp3d hybridization = what geometry and bond angle
– and what possible molecular shapes given the # of lone pairs
trigonal bipyramidal; 90 degrees, 120 degrees, and 180 degrees
- -shapes:
- 0 lone pairs = trigonal bipyramidal
- 1 lone pair = trigonal-based pyramid
- 2 lone pairs = trigonal planar or T-shaped
sp3d2 hybridization = what geometry and bond angle
– and what possible molecular shapes given the # of lone pairs
octahedral; 90 degrees
- -shapes:
- 0 lone pair = octahedral
- 1 lone pair =square-based pyramid
- 2 lone pairs = square planar
Rate the following from LONGEST wavelength to SHORTEST wavelength:
- AM/FM/TV waves
- Infrared
- Gamma Rays
- Microwaves
- Ultraviolet
- Visible - Red
- Visible - Purple
- X-Rays
(1) AM/FM/TV waves
(2) Microwaves*
(3) Infrared*
(4a) Visible - Red
(4b) Visible - Purple
(5) Ultraviolet*
(6) X-Rays*
(7) Gamma Rays*
*note - some may have overlapping wavelengths
Calculate Work done given Force and displacement
Work = displacement * Force(parallel-to-displacement)
Calculate Zeff
Zeff = Z - S
Where Z = Atomic # and S = # of electrons NOT in valence shell
2 major components affecting periodic trends
(1) Zeff = increases going left to right. The net charge exerted on valence electrons. takes into account -proton attraction, -interaction with neutrons, and -repulsion (shielding) due to core electrons. Zeff = proton charge - core electron repulsion
(2) Valence Shell: increases going from top to bottom
the 4 major periodic trends to be aware of
As move bottom left to top right:
(1) Atomic size decreases
(2) ionization energy (energy required to remove outermost electron from atom in gas phase) increases
(3) Electron affinity increases
(4) Electronegativity increases
ionization energy vs. electron affinity vs. electronegativity
Ionization energy = energy required to remove outermost electron from atom in gas phase. Becomes a cation
____
Electron Affinity = energy associated with an atom gaining an electron in its gas phase
____
Electronegativity = tendency to hold shared electrons with another atom within a bond
Major periodic trend - rule that is broken
1/2 fulled and fulled subshells have special stability
N ionization energy is greater than O b/c N loses its 1/2 filled subshell and O gains a 1/2 filled subshell
Radius within a period: compare neutral atoms with cations and anions
Cations < neutral atoms < anions
because losing electrons means less repulsion, and gaining electrons means more repulsion
Radius trends in periods and groups
- radius decreases left to right b/c Zeff increases
- radius increases top to bottom b/c # of electron shells increase
Radii of transition metals: trend in a row
have ~the same radii in the same row
major periodic trend - rule that is broken about radii size
He > H (likely due to shielding)
Low ionization energy —- what that means for reduction and oxidation potential
Smaller value for reduction potential and larger value for oxidation potential (b/c easier to oxidize)
Negative vs positive values for electron affinity
more negative = greater electron affinity (b/c means more energy is released, which is favorable)
Most and least EN elements
Most = F (4.0); Least = Na (0.9)
EN and ionic bonds
if delta(EN) > 2.0, the bond is ionic
Reactivity of alkali metals and alkali earth metals as go down the period
increase as you go down, b/c ionization energy is decreasing (also, alkali metals are more reactive than alkaline earth metals)
defining feature of strong reducing agents
readily lose electrons
Reactivity of chalcogens and halogens as go down the period
reactivity decreases as go down b/c 1st and 2nd electron affinities decrease
spring potential energy
PE(spring) = (1/2) k*(x^2)
how to calculate the amount of energy lost to heat
Q= mc∆t
Power =
work / time
J/s = Watts
Calculate the mechanical advantage of an inclined plane
ME = 1 / sin(theta)
Calculate the mechanical advantage of a pulley system
ME = W / T
___
where W = the weight of the mass and T = the tension
Work done on a system in terms of force, displacement, pressure, and volume
W = F∆T = -P∆V
Total energy change in terms of Pressure, Volume, Heat, Force, displacement, and work
∆E = q - Work = q - F∆d = q + P∆V
what does positive Q vs. negative Q mean
+Q = heat flows from surroundings to system
____
-Q = heat flows from system to surroundings
What does positive Work vs negative Work mean
\+W = work done on system by surroundings -W = work done on surroundings by system
Compare: refrigerator to an engine in terms of work and heat
Fridge: takes in work (applied to a piston) and releases heat vs.
Engine: releases work (expands gas in a piston) and takes in heat
Calculate Impulse
Impulse = F(average)*t = m∆v
What type of reactions generate the greatest changes in free energy and enthalpy
Oxidation-reduction reactions
anode vs. cathode and direction of electron flow
Anode = Reducing agent
Cathode = Oxidizing Agent
E- flow from anode to cathode
Oxidation and reduction in orgo/biochem
Oxidation = often the gain of bonds to oxygen and/or the loss of bonds to hydrogen
___
Reduction = often the loss of bonds to oxygen and/or the gain of bonds to hydrogen
Biological Oxidizing agents vs. biological reducing agents
Oxidizing = usually rich in Oxygen and poor in Hydrogen
___
Reducing = usually poor in Oxygen and rich in hydrogen
NADH generally reduces what? And FADH2 generally reduces what?
NADH => carbonyls
FADH2 => alkene double bonds
How to calculate electromotive force given two reduction potentials
E = E(reduction) + E(oxidation)
-Use E(reduction) of the 1/2 rxn with the HIGHER reduction potential (more positive)
-For E(oxidation), use the 1/2 rxn with the LOWER (or more negative) reduction potential - to find the E(oxidation), just take the negative of its E(red)
____
(Ered = reduction potential of the 1/2 rxns)
Higher Reduction potential means what?
It can be reduced (Gain electrons) more favorably, meaning it is a stronger oxidizing agent
Periodic trends - what is easily oxidized and what isn’t
Easily oxidized (lose e-) = alkali and alkali earth etals (to form + or 2+ cations) _ Don't easily oxidize = precious metals
Calculate the free energy change associated with an EMF
∆Grxn = -nFE(cell)
F = 96500 C/mol n = #electrons/reaction
Unit for Work
J = N/m
Universal rules for Electrical Circuits
(1) e- flow anode->cathode
(2) cations migrate through electric fields to the cathode, and anions migrate through electric fields to thhe anion
Why do you need salt bridges in an electrochemical cell?
They complete the cycle: allow anions to flow to anode to balance out charge distributions from e- flowing to the cathode
Types of Electrochemical Cells, and how they differ
(1) Galvanic = Spontaneous (Ecell > 0) –> release energy in form of e- flow
(2) Electrolytic = Non-spontaneous (Ecell <0) –> used for storage of electrical potential
How to maximize voltage in a galvanic cell (and what happens over time)
increase reactants (cathode ions) and decrease products (anode ions).
Over time, reactants are converted to products until reach equilibrium and reaction stops and gives off no more energy.
At what conditions are Standard EMFs given at
25 degrees celsius, 1 atm, and 1.00m
What is a concentration cell
Anode and cathode contain same species but at different concentrations
Nernst Equation
E(cell) = E* - 2.3RT/nF * logQ
or, at 298K: E(cell) = E* - 0.059/n*logQ
Where Q = [anode]/[cathode]
(where E* = E not)
What is a battery and what does it do?
A galvanic cell (or group of galvanic cells in series)
- they convert electrical potential energy into direct currents,
- by using a reversible oxidation-reduction reaction. they can act as either a galvanic cell OR an electrolytic cell
how does a fluorescent tube work
(1) 2 plates create a potential ∆
(2) Gas ions accelerate towards oppositely charged plates until collide with another gas particle
(3) some KE is absorbed by the other particle which absorbs energy by exciting an electron
(4) When excited e- relaxes back to ground state, a photon is emitted. –> the tube is coated with a fluorescing agent to convert UV radiation into visible light.
How do incandescent light bulbs work
They convert electrical flow into light by passing current through a resistor and a vacuum (vacuum prevents energy from being dissapated within)
–> thermal energy builds up and is released via EM radiation (causing glowing)
How do electrical motors work
an electric flow (current flowing through a loop) induces a magnetic field —> by allowing the induced filed to interact with an external stationary magnetic field, a torque can be exerted on the loop. —> loop realigns with stationary field —> causes induced field to revers —> causing more torque —> and repeat
What is electroplating
The process of reducing ions in solution onto the surface of a conducting material —> happens at the cathode, so cathode gains a thin film of the reduced metal on its surface
what does it mean to galvanize a metal? And why is it done
- add a more reactive metal to be preferentially oxidized over the metal being preserved —> so using a metal with a higher oxidation potential.
- It’s done b/c metals exposed to the environment will oxidize over time, so this preserves the metal
Formula for phosphate ion
PO4 (3-)
Rusting is an example of _____ (oxidation or reduction)?
OXIDATION
Aziuthal quantum number
determines its orbital angular momentum & describes the shape of the orbital
farsightedness = the image forms ______ and so you need a ____ lens
The image forms behind the retina, so you need a converging lens
longitudinal vs. transverse waves
longitudinal = direction of wave vibration is parallel to propagation (collisions btwn neighborhing particles); transverse = direction of wave vibration is Perpendicular to wave propagation
sound is what type of wave
longitudinal
IR frequency of C=O bond
1650 - 1750 cm-1
IR frequency of O-H bond
2500 - 3300 cm-1
IR frequency of Alkane (C triple bond C)
2100-2260 cm-1
IR frequency of C-O bond
1000 - 1320 cm-1
What is the fingerprint region
IR spectrum that lies in between that of functional groups (1500 to 4000 cm-1) and Aromatic rings (under ~500 cm-1) —> so, roughly 500 - 1500 cm-1; signals here are unique to each particular molecule
