General Chemistry – Lab Final

percent error
(average value – true value)
—————————- x 100%
true value
coefficient of variation
(standard deviation)
——————— x 100%
mean(not S.D.’s mean)
percent difference
|(Value 1 – Value 2)|
———————- x 100%
| Avg. of values |
standard deviation (excel)
formulas > more functions > statistical > stdev.s
measurements related to systematic error
absolute error and percent error
measurements related to random error
standard deviation and coefficient of variation
measurements related to accuracy
absolute error and percent error
measurements related to precision
standard deviation and coefficient of variation
define accuracy
closeness of measured value to the true value, correctness
define precision
closeness of measured values to each other, reproducibility
calculate moles of a substance given grams
# grams / molecular mass of compound
calculate grams of substance given moles
multiply # moles by molecular mass of compound
calculation for concentration
molarity, n (mols of substance) / volume of substance in liters or PPM
calculate parts per million (PPM)
mass of substance in Mg / volume in liters
density
mass / volume
one amp = ? coulombs
one amp = one coulomb of charge per second
charge of an electron
-1.602 x 10 ^ -19 coulombs
40 amp circuit how many coulombs per second?
40
to find the total charge passed through a circuit
multiply time (in seconds) by # of amps passed through
to find # of electrons passed through a circuit
multiply # coulombs by the charge of an electron (750C x [1/1.602×10^-19])
how to type 3.09 x 10^19 into excel
3.09E+19
Avogadro’s number
6.022×10^23
percent yield
actual yield / theoretical yield x 100%
Qrxn
– C calorimeter X Temperature change
Delta H mol (enthalpy change per mol of fuel burned)
Q rxn / n burned (mols fuel burned)
Delta H G (enthalpy change per gram of fuel burned)
1) delta H mol / molecular mass of fuel
2) Q rxn / mass burned
how to calculate energy of one photon
e = hc / lambda
H represents what
plancks constant, 6.626×10^-34 joules per second
C represents what
speed of light, 2.9979×10^8 meters per second
lambda represents what
wavelength in nanometers (must be converted to meters in energy equation)
how to convert from nanometers to meters
multiply the nanometers by (10^-9)
molarity
moles of substance / volume in liters
parts per million
mass of substance in mg / volume in liters
molarity dilution calculation
m1v1 = m2v2
bond angle for linear
180
bond angle for trigonal planar
120
bond angle for tetrahedral
109.5
bond angle for trigonal bypyramidal
90 and 120
bond angle for octahedral
90
bond angle for 2 groups of electrons
180
bond angle for 3 groups of electrons
120
bond angle for 4 groups of electrons
109.5
define hydrocarbons vapor pressure and solubility
high vapor pressure, insoluble
define esters vapor pressure and solubility
high vapor pressure, high to moderate solubility
define alcohols vapor pressure and solubility
low vapor pressure, high to moderate solubility
molecular mass equation for chapter 8
(Mgas)(R = .0821)(Tbath)/(ambient pressure in atm)(Vbottle volume of gas)
how to find mass of gas
Mincrease (avg) + M correction
equation to find M correction
(MM air 29g/mol)(Sample VP atm)(Vbottle in L)/(.0821)(room temp kelvin)
how to determine formula of ester or alcohol
divide its molecular mass by 15, round to nearest whole number, for esters 2 of these numbers will be O atoms, for alcohols one will be an O atom
typical vapor pressure of ester and hydrocarbon
>20torr
typical vapor pressure of alcohol
<10torr
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