1.2 amount of substance Flashcards
definition of a mole
the amount of substance in grams that has the same number of particles as there are atoms in 12g of carbon 12
definition of RAM
the average mass of one atom compared to 1/12 the mass of carbon 12
concentration=
moles/volume
cm^3 to dm^3
/1000
cm^3 to m^3
/1,000,000
dm^3 to m^3
/1000
empirical formula
the simplest ratio of atoms of each element in the compound
molecular formula
the actual number of atoms of each element in the compound
why does a crucible need to be dry and reweighed
dry so water does not affect the result, reweighed until a constant mass is reached to make sure reaction is complete
don’t use small amounts because…
too many weighing errors
potential errors when using a gas syringe
gas escapes before bung inserted, not soluble in water so not true amount measured
titration steps
rinse equipment, pipette alkali into conical flask, add acid from burette, make sure jet space is filled, add indicator, not burette reading before and after
why use a conical flask and not a beaker in a titration
easier to swirl
% error calculation
sensitivity error/measurement from apparatus
