some basic concepts of chemistry

atomic mass

mass of 1 atom of any element

mass of an element / (1/12) of 1-C¹² atom

molecular mass

mass of 1 molecular

mass of a molecule / (1/12) mass of 1-C¹² atom

gram molecular mass

mass of 1 mole atom of any element

molar mass

mass of N_A number of particles (calculate in grams)

number of moles with weight

n= given Wt / molecular wt

no. of moles with molecules

no. of particals / 6.02 × 10²³

no. of moles with volume

Volume at stp / 22.4 l

percentage composition

weight of the element / total molecular weights x 100

density absolute (g/ml) in case of solids and liquid

mass / volume

density absolute (g/l) in case of gas

d = PM / RT

specific gravity (unitless)

density of substance / density of water at 4 C

relative density (unitless)

d₁/d₂ = M₁ / M₂

minimum molecular mass (condition)

for a molecular mass to be minimum, then, no. of atom should be 1

vapour density

M₁ /M_h2 = M₁ / 2 ( density of the gas with respect to hydrogen gas at constant T,P

avarage atomic weight for isotopes

molecular formula

mean molar mass

mole fraction

percentage by mass