Test 3 Formulas, units and symbols Flashcards Preview

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Flashcards in Test 3 Formulas, units and symbols Deck (47):
1

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

2

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 )

3

Units: Urms

m/s, meters per second

4

Units: R

8.314 J / mol*K

5

Kinetic molecular theory states

at any given temperature, a population of gas particles has the same average kinetic energy

6

Root-Mean-Square_Speed is

The speed of a gas molecule possessing the average kinetic energy

7

Effusion is the

process by which gas molecules escape through a small hole

8

Formula: Graham's Law

Rate1 / Rate2 = sqrt(M2 / M1)
Rate = Urms
M = molar mass of the gas, ( kg/mol )

9

Formula: First law of thermodynamics

dEsys = -dEsurr
dE = Change of energy

10

Formula: dEsys =

dEsys = q + w
q = dHeat
w = work

11

Formula: w =

w = -PdV
w = work, under conditions of constant pressure
P = pressure
dV = change in volume

12

-qlost = qgained, is used in

Calorimetry

13

Calorimetry is the

science associated with determining the heat transfer during chemical reactions or physical changes

14

Formula: Heat capacity =

qcal = C*dT
qcal = J
C = Heat capacity, J / degC
dT = Change in temperature

15

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

16

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

17

Formula: dH*rxn =

dH*rxn = Sum (dH*fproducts) - Sum (dH*freactants)
dH*rxn = Standard enthalpy change
dH*f = Standard enthalpy of formation

18

Heat capacity (C)is

the amount of energy requried to raise the temperature of an entire object by 1 degC

19

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

20

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

21

Formula: qp =

qp = dH
qp = heat at constant pressure
dH = change of enthalpy

22

Unit: dE =

change of energy

23

Unit: dH =

change of enthalpy

24

Endothermic reaction

heat is absorbed, and the system has a positive symbol

25

Exothermic reaction

heat is released, and the system has a negative symbol

26

Open system

Mass: exchanges mass with surroundings
Heat: exhanges heat with surroundings

27

Closed system

Mass: Does not exchange mass with surroundings
Heat: Exchanges heat with surroundings

28

Isolated system

Mass: Does not exhange mass with surroundings
Heat: Does not exchange heat with surroundings

29

Standard heat of formations is also known as

The standard enthalpy of formation

30

Standard state rules for a gas

the standard state for a gas is the pure gas at a pressure of exactly 1 atm

31

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

32

standard state rules for a substance in solution

the standard state for a substance in solution is a concentration of exactly 1M

33

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

34

standard enthalpy of formation, symbol and rules

dH*f,
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: dH*f = 0

35

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

36

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

37

Relationships involving dHrxn (3)

1. If a chemical equation is multiplied by some factor, then dHrxn is also multiplied by the same factor
2. if a chemical equation is reversed, then dHrxn changes sign
3. 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

38

Units and symbol: frequency

Hz = 1/s
v

39

units and symbol: wavelength

meters
lamduh, (upside down y)

40

Wavelength definition

the distance between two analogous points on successive waves

41

amplitude definition

vertical measurement from the midline of a wave to the top of a peak or bottom of a trough

42

frequency definition

is equal to the number of complete wave cycles that pass through a point in one second

43

The greater the number the frequency the ______ the energy

greater

44

the greater the number of the wavelength the ____ the energy

lower

45

Frequency and amplitude are directly proportional to the _____

energy

46

frequency and wavelength are ______ proportional to the energy

inversly

47

order of waves the the electromagnetic spectrum by low energy to high energy

radio, microwave, infrared, visible light, ultraviolet, x-ray, gamma ray