1.2 the mole concept Flashcards
relative atomic mass
The relative atomic mass (Ar) is the weighted average mass of an atom compared to 1/12 the mass of an atom of carbon-12. As it is a relative scale, values for relative atomic masses are dimensionless (do not have units).
relative Mr
The relative formula (or molecular) mass (Mr) of a compound is the weighted average mass of the compound compared to 1/12 the mass of an atom of carbon-12. As it is a relative scale, values for relative formula (or molecular) masses are dimensionless (do not have units).
avogadro constant (L or Natoms-Na)
number of particles per mole
1 mole = 6.02x10^23
(no units)
molar mass
mass in grams of one mol of a substance
unit g mol^-1
number of particles (given mass)
- divide by Mr to find no. moles
- multiply by avogadro constant
mass of 1 molecule
Mr of substance/avogadro constant
mass will be v small as individual molecules have v small masses
empirical formula
lowest whole number ratio of atoms (or ions) in a compound.
molecular formula
A molecular formula is the actual number of atoms in a compound.
calculating empirical formula
it can be calculated from % comp by mass
i rly cant be bothered w calculations its v in-your-face
oh wel
limiting reactant
limits the amount of product that can be made in a chemical reaction
excess reactant
reactant that remains unused at the end of a reaction.
theoretical yield
The theoretical yield is the maximum amount of product that can be produced assuming that all the limiting reactant has reacted.
actual yield
The actual yield is the amount of product that is actually produced in a chemical reaction.
percentage yield (formula
actual yield/theoretical yield x 100%
