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45 Cards in this Set

  • Front
  • Back
unit of energy
1 J =
1 J = 1 kg(m/s)^2
unit of energy
1 calorie =
4.184 J
(∆T) =
(∆H) =
(∆E) =
Change in Temperature, Heat, Energy = (Final - Initial)
Exothermic helpers
- ; Gives off heat; releases heat; adding heat; hot; reacts
Endothermic helpers
+ ; Removing heat; absorbs heat; takes in heat; cold; decomposes; dissolving in water is always endo
kinetic energy formula =
Ek = 1/2 mv^2
m = mass = kg
v = velocity = m/s
kinetic energy question example
Calculate the kinetic energy in Joules of a 1200 kg automobilie moving at 18 m/s. Convert energy from Joules to calories.; use kinetic energy formula and calorie to Joule conversion
internal energy formula
answer in Joule; (∆E) = q + w
q = heat, w = work
q helpers
+ means system gains heat;
- means system loses heat
w helpers
+ means work done on system
- means work done by system
- w quote
"if system works on the surrounding..."
+ work quote
"if the surrounding works on the system..."
∆E helpers
+ means net gain of energy by system; decompose
- means net loss of energy by system; reacts
internal energy questions example
Calculate the ∆E of the system and determine whether the process is endothermic or exothermic. A balloon is cooled by removing .655 kJ of heat. It shrinks on cooling and the atmosphere (surrounding) does 382 J of work on the balloon (system).
enthalpies of reaction question example
4 step problem; endo or exo; calculate heat transferred when g is decomposed; given a reaction, ∆H during reaction is kJ. How many grams of product produced; how many J heat released when g reacts w/O2 at constant pressure
Conversion clue
if question as for a conversion, ∆ mol to mol; if no conversion is asked, use mols from equation
when reactions reverses, you must...
switch the sign given for ∆H
first law of thermodynamics
energy is conserved; not created or destroyed; any energy lost by a system is gained by surroundings, and vice versa
Hess's Law
states that if a reaction is carried out in a series of steps, ∆H for the overall reaction will equal the sum of the enthalpy changes for the individual steps
a thermodynamic function; means to warm; accounts for heat flow in processes occurring at constant pressure; the change equals the heat gained or lost at constant pressure
basis of Hess's Law
We can calculate for any process, as long as we find the route; used for more difficult processes to measure
Hess's Law helpers
must multiply/divide both process and ∆H before cancellations; same side add, opposite side cancels; if process reverses, must switch ∆H sign
calorimetry formula
Heat = mass x specific heat x ∆T
q = kg x c x ∆T
specific heat = (rule)
= heat/massx∆T = J / g℃
calorimetry question example
specific heat of ethylene glycol is 2.42 J/gK. How many J of heat are needed to raise the temp. of 62.0 g of ethylene glycol from 31.1 ℃ to 40.5 ℃.
calorimetry rule
never convert ℃ to K and vice versa; always equal
specific heat of water (l)
indicates the amount of heat that must be added to 1 gram of a substance to raise its temperature by 1 K (or 1 ℃); at 14.5-15.5℃ is 4.184 J/ g-K
molar heat capacity of water (l)
heat capacity of one mole of a substance
specific heat
= q / m x change T= J / g x degree C
-can rearrange to form new formuula
relating heat, temp change and heat capacity
change in H(f rxn) = change in H(f product) - change in H(f reactant) = in kJ

Hf = heat of formation, rxn = reaction, small o = standard enthalpy and not degree

use values for Hf in kJ/mol given by appendix C
c = lambda x v
Light as a wave:
c = speed of light = 3.0 x 10^8 m/s, lambda = wavelength in meters, v = frequency in s^-1 or 1/s; (can be rearranged)
E = hv
light as a particle (photon):
E = energy of photon in J, h = Plank's constant (6.626 x 10^-34 J-s, v = frequency in s^-1 or 1/s; (can be rearranged)
lambda = h/mv
matter as a wave:
lambda = wavelength, h = Plank's constant, m = mass of object in kg; v - speed of object in m/s
change in x = change (mv) >= h/4pie
Heisenberg's uncertainty principle; the uncertainty in position (change in x) and momentum (change in mv) of an object cannot be zero; the smallest value of their product is h/4pie
Max Plank
gave the name quantum (meaning 'fixed amount') to teh smallest quantity of energy that can be emitted or absorbed as whole numbers of electromagnetic radiation; proposed E=hv;
Albert Einstein
used Plank's theory to explain the photoelectric effect; E=hv; when radiant energy strikes a metal surface, it behaves as a stream of tiny energy packets called photons
Bohr - 3 postulates
proposed a model of the hydrogen atom that explains the line spectrum 1. only orbits of certain radii, are permitted for the electron in an H atom; 2, an electron in a permitted orbit has a specific energy and is in an "allowed' energy state; 3. energy is emitted or absorbed as a photon
Johann Balmer
showed wavelengths of four visible lines of hydrogen on spectra in a formula that related the wavelength of visible line spectrum to integers; extended to Rydberg's equation
Rydberg's equation
1/lambda = Rh(1/n squared,1 - 1/n squared,2); n2 is larger than n1
Rh is constant = 1.096776 x 10^7 m^-1
discovered the nuclear nature of the atom
Bohr's formula
E = (-hcRh)(1/n squared) = -2.18 x 10^-18 J(1/n squared); and he gave us orbits
Louis de Broglie
proposed wavelength of the electron depons on mass and its velocity; lambda = h/mv
Pauli's excursion principle
states no two electrons in an atom can have the same set of four quantum numbers n, l, m l, m s; and the orbitals are filled in order of increasing energy, with no more than two electrons per orbital
wave equation; his work opened a new way of dealing with subatomic particles; quantum mechanics or wave mechanics; also gave us orbitals
Hund's rule
for degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximised