Normality & Equivalent Mass - Redox Reactions Video Lecture | Physical Chemistry

in this video lecture we will understand
about equivalent mass for solutions and
normality equivalent mass may be defined
as amount of a substance which reacts
with one gram of hydrogen eight gram of
oxygen or 35.5 gram of chlorine formula
for equivalent mass is gram atomic mass
or gram molecular mass divided by n
factor so if we know the N factor we can
easily find out the equivalent mass and
factor may be charged acidity basicity
or change in oxidation number let's
understand one by one first of all
equivalent mass of an acid it is equal
to molecular mass divided by basicity
basicity it is equal to number of
replaceable hydrogen atom in one
molecule of acid for example in case of
HCl only one hydrogen is replaceable so
its basicity is one whereas in case of
sulfuric acid two hydrogens are
replaceable so its basicity is two
similarly basicity of various other
acids are for HCl one h2 so4
two hno3 one for acetic acid one for
oxalic acid two h3po4 three h3 p r3 2 h3
p o2 basicity is one
so if we need to determine equivalent
mass of h2so4 so according to formula
molecular mass divided by basicity its
molecular mass is 98 and basis it is two
hands equivalent mass is 49 so in this
manner we can find out equivalent mass
of an asset for base equivalent mass is
equal to molecular mass divided by
acidity acidity may be defined as it is
equal to number of replaceable hydroxide
ion or Oh H ion in a base molecule for
example in case of an image acidity is 1
in case of calcium hydroxide acidity is
2 so for acetic acid we can see there is
one Oh H but on ionization it does not
give overt iron hence acidity is zero
since it gives H I n so it possess
basicity so equivalent mass of NaOH is
molecular mass divided by basicity which
is 1 hence equivalent mass is same as
that of molecular mass
for salt equivalent mass is equal to
molecular mass divided by total positive
valency for ion equivalent mass is equal
to formula mass divided by charge per
ion neglecting the sign and for a
reaction equivalent mass of species is
equal to molecular mass divided by
change in oxidation number so remember
students any element or compound possess
fixed molecular mass but it can have
variable equivalent mass depending upon
reaction and change in oxidation number
so now we can say equivalent mass is
equal to gram atomic mass gram molecular
mass divided by n factor gram equivalent
mass it is equivalent mass in gram
number of equivalence is equal to weight
in gram divided by equivalent mass
number of equivalence are also equal to
normality into volume in liter number of
milli equivalents is equal to normality
into volume in milliliters
so now let us understand normality units
of normalities is equivalent per liter
per gram equivalent per liter suits
definition is it may be defined as
number of gram equivalent of solute
present in thousand CC or 1 liter of
solution its SI units are gram
equivalent per decimeter cube and the
formula for normality is number of gram
equivalents divided by volume of
solution in CC in 2000 number of gram
equivalents are equal to wait upon
equivalent mass so we can write another
formula as weight of solute in gram
divided by equivalent mass into volume
of solution in CC in 2000 as we all know
strength is equal to normality into unit
mass so normality is equal to strength
upon equivalent mass if we put the value
of percentage strength so at the place
of strength we can write weight by
volume percentage into 10 divided by
equivalent mass in case of mass
percentage normality is equal to mass
percentage into density into 10 divided
by equivalent mass so the difference
between normality and molarity is in
case of normality we use equivalent mass
whereas in case of molarity we use
molecular mass relation between
normality and molarity is normality is
equal to acidity and basicity into
molarity
normality in terms of molecular
normality may be defined as number of
milli equivalents of solute presenting
one cc of solution so it's another unit
can be number of molecular per cc we can
say