2.1.3 amount of substance Flashcards
what is amount of substance and what is it measured in
the number of particles
units are moles
what is the value of Avogadro’s constant
6.02 x 10^23
what are the equations to find the number of moles
moles = concentration (mol/dm3) x volume (dm3)
moles = mass (g) / Mr
how do we find moles of a gas
moles = volume (dm3) / molar gas volume (24 at rtp)
what is the molar mass
the same as relative molecular mass
what is the ideal gas equation and what units does each component use
pressure (pascals) x volume (m3) = moles x gas constant (8.314) x temperature (kelvin)
what is the empirical formula
it gives the smallest whole number ratio of atoms of each element in a compound
what is the molecular formula
gives the actual number of atoms of each element in a compound
how do we calculate empirical formula
we divide each percentage by Mr and then divide each answer by the smallest answer to get a ration.
if ration is not a whole number multiply so it is
what is the definition of anhydrous
a salt that does not contain water of crystallisation. they can be used as drying agents
what is water of crystallisation
when water molecules are incorporated into the lattice of an ionic compound
how can we remove water of crystallisation
heating so that the water evaporates. measure on a balance until a constant mass is reached
what is the equation for percentage yield
percentage yield = actual mass of product (g) / theoretical maximum product (g) x 100
what is the equation for percentage atom economy
% atom economy = Mr of desired product /
Mr of all products x 100
why is it more sustainable to have a high atom economy
there is less waste products produced and it used up finite raw materials
