Home

Molmassa

Molmassa, also known as molar mass, is the mass of one mole of a substance, expressed in kilograms per mole (kg · mol⁻¹) or more commonly in grams per mole (g · mol⁻¹). One mole corresponds to Avogadro’s number (6.022 × 10²³) of elementary entities, such as atoms, molecules, ions, or formula units. The molar mass of a compound is obtained by summing the atomic masses of all atoms in its chemical formula, taking isotopic abundances into account.

For an element, the standard atomic weight listed in the periodic table represents its average molar mass,

Molar mass is central to stoichiometric calculations, converting between mass and amount of substance. By dividing

weighted
by
the
natural
isotopic
distribution.
For
example,
carbon
has
a
standard
atomic
weight
of
12.011 g · mol⁻¹,
reflecting
the
presence
of
both
¹²C
and
¹³C
isotopes.
In
a
chemical
compound,
the
molar
mass
can
be
calculated
by
multiplying
the
number
of
each
type
of
atom
by
its
atomic
mass
and
adding
the
results.
Water
(H₂O)
thus
has
a
molar
mass
of
(2 × 1.008 + 15.999) g · mol⁻¹ ≈ 18.015 g · mol⁻¹.
a
sample’s
mass
by
its
molar
mass,
one
obtains
the
number
of
moles
present,
which
can
then
be
used
with
balanced
chemical
equations
to
predict
reactant
consumption
and
product
formation.
It
also
underlies
concepts
such
as
molar
concentration
(molarity)
and
the
determination
of
empirical
and
molecular
formulas
from
experimental
data.
Accurate
molar
masses
are
essential
in
fields
ranging
from
analytical
chemistry
to
pharmaceutical
formulation
and
material
science.