amount of substances in all papers (3.1.2) Flashcards
what is the relative atomic mass (Ar)?
the average mass of one atom compared to one twelfth of the mass of one atom of carbon 12.
no units.
what is the relative molecular mass (Mr) ?
the average mass of a molecule compared to one twelfth of the mass of one atom of carbon 12.
for covalent compounds
no units
what is the avogadros constant?
the number of particles in a mole.
(6.022x10^23)
how do you work out the number of moles in pure solids and liquids?
moles= mass/Mr
units: grams
mol
how do you work out the number of moles in pure solids and liquids?
moles= mass/Mr
units: grams
mol
how do you work out the mass of 1 mole of pariticles?
avogadros constant X mass of 1 parrticle.
how to work out the number of particles?
number of moles x avogadros constant
how do you convert kPa to Pa?
x1000
how do you convert cm^3 to m^3?
divide by 10^6 or x10^-6
how do you convert dm^3 to m^3?
divide by 10^3 or x10^-3
how do u convert C to kelvins?
add 273
how do you work out the empirical formula and molecular formula from it?
1: set out the elements with
their masses/percentage.
2: divide each mass by their Mr.
3: divide all them by the smallest
value.
4: give whole number ratio in
empirical formula.
5: molecular formula =
n(empirical formula)
explain the water of crystallisation practical (hydrated salt)
- weigh an empty crucible.
- add 2g of hydrated calcium
sulfate to the crucible and
weigh again. - heat with a bunsen burner for
5 mins and let it cool. - weigh the crucible and
contents again. - heat and reweigh again until
you reach a constant mass to
ensure salt has become
anhydrous.
how do you work out atom economy?
mass of desired product
————————————–x100
total mass of reactants
how do you work out percentage yield?
actual mass of product
————————————–x100
maximum theorectical mass of product
