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45 Cards in this Set
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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


enthalpy

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 14.515.5℃ is 4.184 J/ gK


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 Js, 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 

Rutherford

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


Schrodinger

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
