moles, concentrations, gas equations.
Moles definition
One mole of any substance contains the same number of particles as there are atoms of C-12 in exactly 12g Carbon-12.
Formulae for actual number of particles.
amount in moles = number of particles/ Avogadro’s number.
formulae for moles
Moles = Mass/ Mr
formula for percentage composition.
% = total Ar of element/total Mr of compound x 100
formula for mass of element
mass of element = Ar of element/ Mr of compound x mass of compound
Formulae for % yield
% yield = actual mass of product/ maximum mass of product x 100
Formula for atom economy
atom economy = mass required of product/mass of reactants or products x 100
Formula for moles in liquids
n = concentration (mol dm-3) x volume (dm-3)
The formula for moles in gases when conditions are:
25 C → 1 atm
0 C → 1 atm
n = volume / molar volume
Ideal gas equation
PV = nRT
What do the symbols in PV = nRT stand for?
P = Pascals
V = volume (m3)
n = moles
R = constant in data booklet
T = temperature (K)
Combined Gas Law:
P1V1/T1 = P2V2/T2 (remove whatever the question states is constant.)