amount of substance Flashcards
define: Ar
average mass of isotopes of an element / 1/12 x mass od one atom of 12C
define: Mr
average mass of one molecule x12 / mass of one atom of 12C
how to you calculate moles using mass and Mr?
mass = moles X Mr
how do you calculate moles using concentration and volume?
n = mv / 1000
how do you calculate percentage error?
% error = maximal error / titre volume x 100
what is the ideal gas equation?
PV = nRT
what units should:
pressure
temperature
be in in the ideal gas equation?
Pa
K
how do you go from cm3 to dm3?
/ 1000
how do you go from kPa to Pa?
x 1000
how do you go from *C to K
+ 273
how do you work out empirical formula?
- workout the percentage of each element (use these as masses)
- convert masses to moles
- divide all values by the smallest number of moles to find the ratio
- simplify to a whole number
how do you work out % atom economy?
mass of desired product / total mass of reactants x 100
how do you work out % yield?
actual mass of product / predicted mass of product x 100
how do you calculate moles using concentration and volume?
moles = nv / 1000
