Test 3 Formulas, units and symbols Flashcards
Formula: KE avg =
KEavg = 1/2m(Urms)^2 m = mass of the object in kg Urms = root-mean-square-speed of a gas KEavg = average Kinetic energy
Formula: Urms =
Urms = sqrt((3RT)/M) Urms = root-mean-square-speed of a gas sqrt = square root R = Universal gas constant T = Temperature of gas, Kelvin M = molar mass of the gas, ( kg/mol )
Units: Urms
m/s, meters per second
Units: R
8.314 J / mol*K
Kinetic molecular theory states
at any given temperature, a population of gas particles has the same average kinetic energy
Root-Mean-Square_Speed is
The speed of a gas molecule possessing the average kinetic energy
Effusion is the
process by which gas molecules escape through a small hole
Formula: Graham’s Law
Rate1 / Rate2 = sqrt(M2 / M1)
Rate = Urms
M = molar mass of the gas, ( kg/mol )
Formula: First law of thermodynamics
dEsys = -dEsurr dE = Change of energy
Formula: dEsys =
dEsys = q + w q = dHeat w = work
Formula: w =
w = -PdV w = work, under conditions of constant pressure P = pressure dV = change in volume
-qlost = qgained, is used in
Calorimetry
Calorimetry is the
science associated with determining the heat transfer during chemical reactions or physical changes
Formula: Heat capacity =
qcal = C*dT qcal = J C = Heat capacity, J / degC dT = Change in temperature
Formula: Molar heat capacity =
qmol = n*Cp*dT gmol = J n = number of moles Cp = molar heat capacity, J / mol * degC dT = Change in temperature
Formula: specific heat capacity =
qgram = m*S*dT qgram = J S = specific heat capacity, J / g*degC m = mass in grams dT = Change in temperature
Formula: dH*rxn =
dH*rxn = Sum (dH*fproducts) - Sum (dH*freactants) dH*rxn = Standard enthalpy change dH*f = Standard enthalpy of formation
Heat capacity (C)is
the amount of energy requried to raise the temperature of an entire object by 1 degC
Molar heat capacity (Cp)
the amount of energy required to raise the temperature of 1 mol of a substance by 1 degC at constant pressure
Specific heat capacity (s) is
the amount of energy required to raise the temperature of 1 gram of a substance by 1 degC at constant pressure
Formula: qp =
qp = dH qp = heat at constant pressure dH = change of enthalpy
Unit: dE =
change of energy
Unit: dH =
change of enthalpy
Endothermic reaction
heat is absorbed, and the system has a positive symbol
Exothermic reaction
heat is released, and the system has a negative symbol
Open system
Mass: exchanges mass with surroundings
Heat: exhanges heat with surroundings
Closed system
Mass: Does not exchange mass with surroundings
Heat: Exchanges heat with surroundings
Isolated system
Mass: Does not exhange mass with surroundings
Heat: Does not exchange heat with surroundings
Standard heat of formations is also known as
The standard enthalpy of formation
Standard state rules for a gas
the standard state for a gas is the pure gas at a pressure of exactly 1 atm
standard state rules for a liquid or solid
the standard state for a liquid or solid is the pure substance in its most stable form at a pressure of 1 atm and at the temperature of interest
standard state rules for a substance in solution
the standard state for a substance in solution is a concentration of exactly 1M
Standard enthalpy change, symbol and rule
dH*, the change in enthalpy for a process when all reactants and products are in their standard states. The degree sign indicates standard states
standard enthalpy of formation, symbol and rules
dHf,
pure compound: the change in enthalpy when one mole of the compound forms from its constituent elements in their standard states
Pure element in its standard state: dHf = 0
Written summary of the dH*rxn = formula
to caldulate dH*rxn, subtract the enthalpies of formation of the reactats multiplied by their stoichiometric coefficients from the enthalpies of formation of the products multiplied by their stoichiometric coefficients
Hess’s law
if a chamical equation can be expressed as the sum of a series of steps, then dHrxn for the overall equation is the sum of the heats of reactions for each step
Relationships involving dHrxn (3)
- If a chemical equation is multiplied by some factor, then dHrxn is also multiplied by the same factor
- if a chemical equation is reversed, then dHrxn changes sign
- if a chamical equation can be expressed as the sum of a series of steps, then dHrxn for the overall equation is the sum of the heats of reactions for each step
Units and symbol: frequency
Hz = 1/s
v
units and symbol: wavelength
meters
lamduh, (upside down y)
Wavelength definition
the distance between two analogous points on successive waves
amplitude definition
vertical measurement from the midline of a wave to the top of a peak or bottom of a trough
frequency definition
is equal to the number of complete wave cycles that pass through a point in one second
The greater the number the frequency the ______ the energy
greater
the greater the number of the wavelength the ____ the energy
lower
Frequency and amplitude are directly proportional to the _____
energy
frequency and wavelength are ______ proportional to the energy
inversly
order of waves the the electromagnetic spectrum by low energy to high energy
radio, microwave, infrared, visible light, ultraviolet, x-ray, gamma ray
