2P-Amount Of Substance Flashcards
What’s relative atomic mass (Ar)
Weighted average mass of an atom of an element, taking into account isotopes, relative to the mass of 1/12 of carbon 12
What’s relative molecular mass (Mr) or molar mass
The sum of the relative atomic masses of the atoms in a molecule
How to convert from cm^3 to dm^3
Divide by 1000
Equation to calculate number of moles
Moles=mass/Mr
Equation to calculate concentration
Conc=mol/vol
Conc=mass/vol
What’s the ideal gas equation
PV=nRT
P= Pressure (Pa)
V= Volume (M^3)
n= Moles
R= Gas constant J/Kj/mol
T= Temperature (K)
How to convert from cm^3 to M^3
Dive by 10^6
How to convert from °C to K
Add 273
What’s absolute uncertainty
The true numerical value, indicates a range where the true value is
What’s percentage uncertainty
Uncertainty is expressed as a proportion of the measurement
Allows total uncertainty to be found when multiple variables are used
Equation for % uncertainty for readings
Error/ measurement then x100 to get percentage
What’s a measurement
Value taken as the difference between two values e.g change in temp
Equation for % uncertainty for measurements
(Error 1 + error 2)/measurement x 100
What’s empirical formula
The simplest whole number ratio of the atoms of each element present in a compound
Equation for atom economy
Mr of desired product/ Mr of reactants
Equation for % yield
Actual yield/ theoretical yield x 100 Actual yield is the smaller number
How to determine the error of a value
Half the smallest unit
27.2 —> 0.2/2 —> + or - 0.1
Ammonium
NH4 +
Ammonia
NH3
Carbonate
CO3 2-
Hydroxide
OH -
Nitrate
NO3 -
Nitrite
NO2 -
Sulphite
SO3 2-
