How to calculate normmality in chemistry?
Summary
TLDRThis lecture introduces the fundamental concepts of equivalent mass and normality in chemistry. It explains the dissociation of acids and bases in water, how to calculate equivalent mass using molar mass and the ionization factor 'x', and distinguishes between molar mass and equivalent mass. The script further elucidates the concept of normality, its relationship with molarity, and how to calculate it. It also covers practical examples and numerical problems to solidify understanding, making complex chemical concepts accessible and engaging.
Takeaways
- 🧪 The concept of dissociation or ionization of acids and bases in water is explained, where acids like HCl ionize into hydrogen ions and bases like sodium hydroxide ionize into hydroxide ions.
- 🔢 The script introduces the concept of equivalent mass, equivalent weight, and gram equivalent, which are used to measure the reactive capacity of a molecule.
- 📚 The formula for calculating equivalent mass is given as the molar mass of a molecule divided by the number of ions it produces (x).
- 📉 The script provides an example of calculating the equivalent mass of H2SO4, which has a molar mass of 98 grams and produces two hydrogen ions, resulting in an equivalent mass of 49 grams.
- 📈 The difference between molar mass and equivalent mass is clarified, with molar mass being the mass of one mole of a molecule and equivalent mass being its reactive capacity.
- 📖 The script teaches how to calculate the equivalent mass of substances when the mass is given, using the formula: given mass divided by equivalent mass to find grams equivalent.
- 📝 The concept of normality is introduced, which is the concentration of a solution measured in terms of gram equivalents of solute per liter of solution.
- 🔑 The relationship between molarity (M) and normality (N) is explained as N = M * x, where x is the number of ions produced by the solute.
- 📉 The script demonstrates how to calculate the normality of a solution by dissolving a given mass of a substance in a given volume of water and then converting the mass to grams equivalent.
- 📌 An example is provided to calculate the normality of a solution of calcium hydroxide, showing the steps of converting mass to grams equivalent and then to normality.
- 🔍 The script concludes with an advanced numerical example, explaining how to calculate the mass of H2SO4 in a semi-normal solution, using the given normality and volume.
Q & A
What is the basic concept of dissociation or ionization of acids and bases in water?
-Dissociation or ionization is the process where an acid or base breaks down into ions when added to water. For example, HCl ionizes into hydrogen ions (H+) and chloride ions (Cl-), while sodium hydroxide (NaOH) ionizes into sodium ions (Na+) and hydroxide ions (OH-).
What does 'x' represent in the context of acid and base ionization?
-'x' represents the number of hydrogen ions (H+) or hydroxide ions (OH-) that an acid or base produces when it ionizes in water. For instance, in HCl, x equals 1 because each molecule produces one hydrogen ion.
What is the difference between molar mass and equivalent mass?
-Molar mass is the mass of one mole of a substance, measured in grams per mole. Equivalent mass, on the other hand, is a measure of the reactive capacity of a molecule, calculated by dividing the molar mass by the number of ions 'x' that the molecule produces upon dissociation.
How is the equivalent mass of H2SO4 calculated?
-The equivalent mass of H2SO4 is calculated by dividing its molar mass (98 grams per mole) by the number of hydrogen ions it produces (x = 2), resulting in an equivalent mass of 49 grams.
What is the concept of normality in chemistry?
-Normality is a measure of concentration that represents the number of gram equivalents of solute dissolved in one liter of solution. It indicates how many grams of a substance have the capacity to react in a given volume of solution.
How can you calculate the normality of a solution if you know the mass of the solute?
-To calculate the normality, first determine the molar mass of the solute, then find the equivalent mass by dividing the molar mass by the number of ions 'x'. Next, calculate the number of grams equivalent of solute by dividing the given mass by the equivalent mass. Finally, divide the number of grams equivalent by the volume of the solution in liters to find the normality.
What is the relationship between molarity (M) and normality (N)?
-The relationship between molarity and normality is given by the formula N = M × x, where 'x' is the number of ions produced by the solute upon dissociation.
How do you calculate the mass of H2SO4 in a semi-normal solution given a specific volume?
-To find the mass of H2SO4 in a semi-normal solution, first calculate the number of grams equivalent of solute by multiplying the normality (which is half in this case) by the volume in liters. Then, divide this value by the equivalent mass of H2SO4 to find the mass of H2SO4 present.
What does '2M H3PO4' mean in terms of molarity?
-'2M H3PO4' means that the molarity of phosphoric acid (H3PO4) is 2 moles per liter. Since there are three hydrogen ions in H3PO4, the normality would be 6N (2M × 3).
How can you find the number of grams equivalent of solute in a given mass of a substance?
-To find the number of grams equivalent of a solute, divide the given mass of the substance by its equivalent mass. This will give you the amount of the substance that has the capacity to react.
Can you provide an example of calculating the normality of a solution using the information from the script?
-Sure. If you dissolve 4 grams of H2SO4 in 500 ml of water, first convert 500 ml to liters (0.5 L). Then, calculate the equivalent mass of H2SO4 (49 grams) and find the number of grams equivalent of solute (4 grams / 49 grams ≈ 0.0816 grams). Finally, calculate the normality by dividing the grams equivalent by the volume in liters (0.0816 grams / 0.5 L = 0.16N).
Outlines
🧪 Basic Chemistry Concepts: Normality and Equivalent Mass
This paragraph introduces the fundamental concepts of chemistry, specifically focusing on normality and equivalent mass. It explains the dissociation or ionization of acids and bases in water, using HCl and sodium hydroxide as examples. The paragraph also delves into the calculation of equivalent mass, emphasizing its importance in determining the reactive capacity of a molecule. The concept of molar mass is contrasted with equivalent mass to highlight their differences and uses in chemistry.
📚 Calculation of Equivalent Mass and Gram Equivalent
The second paragraph provides a step-by-step guide on calculating the equivalent mass of various substances, including HCl, sodium hydroxide, and sodium carbonate. It explains the necessity of knowing the molar mass and the value of 'x', which represents the number of ions produced upon dissociation. The paragraph further illustrates how to calculate the number of grams equivalent given a certain mass of a substance, using examples with H2SO4 and sodium hydroxide to demonstrate the process.
🔍 Understanding Normality and Its Calculation
This paragraph explores the concept of normality, its relationship with molarity, and how it measures the concentration of a solution based on the reactive capacity of the solute. It explains that normality is defined as the number of gram equivalents of solute dissolved in one liter of solution. The paragraph also provides a method to calculate the normality of a solution, using H2SO4 as an example, and emphasizes the importance of converting volume measurements to liters and understanding the role of 'x' in the calculation.
📉 Advanced Normality Calculations and Conceptual Understanding
The fourth paragraph builds upon the previous discussions by teaching advanced normality calculations, including how to determine the normality of solutions with given molarity values and how to calculate the mass of a solute in a semi-normal solution. It explains the relationship between molarity and normality using the formula N = M × x, where 'M' is molarity and 'x' is the number of ions. The paragraph also provides a numerical example to calculate the mass of H2SO4 in a binormal solution, reinforcing the understanding of normality calculations.
📝 Final Thoughts on Normality and Practical Application
The final paragraph wraps up the lecture by summarizing the key points about normality and providing a practical example of calculating the mass of H2SO4 in a given volume of solution. It reiterates the importance of understanding normality in chemistry and its application in various chemical calculations. The paragraph also emphasizes the significance of the relationship between molarity and normality and how it can be applied to solve complex problems in chemistry.
Mindmap
Keywords
💡Normality
💡Equivalent Mass
💡Molarity
💡Dissociation
💡Ionization
💡Molar Mass
💡Gram Equivalent
💡Reactive Capacity
💡Acids and Bases
💡Solute and Solvent
💡Numericals
Highlights
Introduction to the basic concept of equivalent mass and equivalent weight.
Explanation of how to calculate equivalent mass.
Dissociation or ionization of acids and bases in water.
The significance of 'x' in representing the number of ions produced by a molecule.
Molar mass calculation for H2SO4 and its interpretation.
Understanding equivalent mass in terms of reactive capacity of a molecule.
How to calculate the equivalent mass of HCl and NaOH.
Calculation of equivalent mass for sodium carbonate considering positive ions.
Method to calculate the number of grams equivalent from given mass.
Definition and calculation of normality in comparison to molarity.
Explanation of the relationship between molarity and normality (N = M * x).
Practical calculation of normality for solutions of H2SO4 and calcium hydroxide.
How to calculate the mass of solute in a semi-normal solution.
The concept of different normality solutions like binormal and centi-normal.
Advanced numerical example calculating the mass of H2SO4 in a binormal solution.
Summary of the key concepts of normality and its practical applications.
Transcripts
how to calculate normality and chemistry
well i challenge you that you will not
find this type of simple explanation
anywhere in this lecture we will learn
the basic concept of equivalent mass and
equivalent weight
how to calculate equivalent mass
basic concept of normality and
numericals of normality so watch this
lecture till the end and you will learn
something very simple
firstly let me teach you the concept of
dissociation or ionization of acids and
bases and water
for example consider an acid like hcl
and base like sodium hydroxide now when
we add hcl to water
it breaks down our ionizes into hydrogen
ion and chlorine ion
here the number of hydrogen ion is
represented by x
so x is equal to one
thus in case of acid this x is equal to
1 means that if we take one molecule of
hcl it will produce one hydrogen ion and
the water
secondly when we add sodium hydroxide to
water it breaks down our ionizes into
sodium ion and hydroxide ion
the number of hydroxide ions is also
represented by eggs
thus in case of base this x is equal to
1 means that
if we take one molecule of sodium
hydroxide it will produce one hydroxide
ion in the water
therefore remember that x represents the
number of hydrogen ion are hydroxide
ions in the solution
now let me teach you the concept of
equivalent mass or equivalent weight or
gram equivalent
which no one is teaching us
remember that
in chemistry these three terms are the
same
now consider one molecule of h2so4
i will explain both its molar mass and
its equivalent mass
for example
there are two atoms of hydrogen one atom
of sulfur and four atoms of oxygen are
present in one molecule of h2so4
the molar mass of hydrogen is one the
molar mass of sulfur is 32 and the molar
mass of oxygen is 16.
after calculation
i get 98 gram per mole
now this is the molar mass of h2so4
here if i ask you what does it mean can
you answer it
well
it means that the mass of one molecule
or one mole of h2so4 is 98 gram let me
repeat it the mass of one molecule or
one mole of h2so4 is 98 gram
just remember that mass of one mole of
any molecule is called molar mass
now what about equivalent mass
well to calculate equivalent mass we
need two things
i mean molar mass of a molecule
and the value of x
we know that the molar mass of h2so4 is
98 gram per mole secondly we can see
that there are two atoms of hydrogen
present in h2so4 which will dissociate
and water are in any solution
so the value of x is 2.
now the formula of equivalent mass is
molar mass of a molecule upon x
the molar mass of h2so4 is 98 gram per
mole and the value of x is 2.
i get equivalent mass is 49 gram
now here comes the climax of this
lecture if i ask you what is meant by
equivalent mass of 49 gram of h2so4 can
you answer this question
well let me explain it
consider 10 bulbs
let 4 bulbs can light up and 6 bulbs are
dead
so we say out of 10 bulbs only 4 bulbs
has the capacity to light up let me
repeat it
out of 10 bulbs only 4 bulbs has the
capacity to light up
similarly we say that out of 98 gram of
h2so4 only 49 gram of h2so4 has the
capacity to react let me repeat it out
of 98 gram of h2so4
only 49 gram of h2so4 has the capacity
to react
therefore we define equivalent mass as
it measures the reactive capacity of a
molecule and grams
so remember that molar mass shows the
mass of a one mole of a molecule and
equivalent mass or gram equivalent shows
the reactive capacity of a molecule and
grams now let me teach you that how can
we calculate equivalent mass of one mole
substance
well consider these substances
we already know that
to calculate equivalent mass we need two
things
molar mass
and value of x
now in hcl there is one hydrogen and one
chlorine
the molar mass of hydrogen is 1 gram and
that of chlorine is 35.5 gram
so the molar mass of hcl is 36.6 gram
secondly we know that there is only one
hydrogen in hcl
so the value of x is fun
now equivalent mass is equal to molar
mass upon eggs or 36.6 upon 1
i get 36.6 gram equivalent
in case of sodium hydroxide there is one
sodium plus one oxygen plus one hydrogen
the molar mass of sodium is 23 gram that
of oxygen is 16 gram and that of
hydrogen is one gram
i get 40 gram
secondly there is only one hydroxide ion
and sodium hydroxide
so the value of x is 1
we know that equivalent mass is equal to
molar mass upon x
or 40 gram upon 1 i get
40 gram
so the equivalent mass of sodium
hydroxide is 40 gram
in case of sodium carbonate there are
two atoms of sodium one atom of carbon
and three atoms of oxygen present and
height the molar mass of sodium is 23
gram that of carbon is 12 gram and that
of oxygen is 16 gram
i get 106 gram
now here there is no hydrogen ion and no
hydroxide iron
so it is a salt in case of salt we
consider positive ions
we know that the positive ion is sodium
there are two atoms of sodium so the
value of x is two
the formula of equivalent mass is
molar mass upon x
or 106 upon 2
i get 53 gram equivalent
so the equivalent mass of sodium
carbonate is 53 gram
thus by this way we can calculate the
equivalent mass of a molecule now let me
teach you one very important concept
which no one is teaching us and without
this concept we cannot calculate
normality easily for instance
how to calculate equivalent mass of a
substance when mass is given
well consider 0.98 gram of h2so4 and 20
gram of sodium hydroxide
now to calculate number of grams
equivalent and
0.98 gram of h2so4
i follow three steps
i find molar mass then i calculate
equivalent mass
and lastly i find the number of gram
equivalent of h2so4
we already know that the molar mass of
h2so4 is 98 gram
secondly we know that the formula of
equivalent mass is molar mass upon x the
molar mass of h2so4 is 98 gram
so i write here 98 gram
there are two ions of hydrogen so the
value of x is 2 and i write here 2.
after calculation i get 49 gram
equivalent
now listen carefully the formula of
number of grams equivalent is equal to
given mass upon equivalent mass
we can see that the given mass is
0.98 gram
and the equivalent mass is 49 gram
thus i plug in all these values in this
equation
after calculation
i get 0.02
gram
now listen carefully if i ask you
what does this 0.0 gram means can you
answer it
well it is simple
i mean if you take
0.98 gram of h2so4
only 0.02 gram has the capacity to react
let me repeat it
if you take
0.98 gram of h2so4
only 0.02 gram has the capacity to react
now in case of 20 gram of sodium
hydroxide i again follow the three steps
we have already calculated the molar
mass of sodium hydroxide which is 40
gram
secondly we know that the formula of
equivalent mass is molar mass upon x
the molar mass of sodium hydroxide is 40
gram and the value of x is one because
there is only one hydroxide ion
thirdly
we know that the formula of number of
grams equivalent is equal to given mass
upon equivalent mass
the given mass is 20 gram and the
equivalent mass is 40 gram i get
0.5 gram
now this 0.5 gram equivalent means that
if we take 20 gram of sodium hydroxide
only 0.5 has the capacity to react
let me repeat it
if we take 20 gram of sodium hydroxide
only 0.5 gram has the capacity to react
therefore by the help of these three
steps we can easily calculate the number
of gram equivalent and given masses
if you have learned all these concepts i
congratulate you you have already
learned the concept of normality
now what is normality
well i always teach molarity and
normality together
remember that
they both measure the concentration of a
solution
for example
if i take one mole of hcl
and i dissolve it in one liter water
i say that the molarity of this solution
is 1 m
so molarity is defined as
number of moles dissolved in 1 liter
solution
on the other hand
consider that
i take hcl
and we know that its equivalent mass is
36.6 gram i dissolve it in one liter
water
so we say that the normality of this
solution is 1n
so normality is defined as the number of
gram equivalent of solute dissolved in 1
liter solution let me repeat it
the number of gram equivalent of solute
dissolved in 1 liter solution
here let me ask you one of the most
difficult question which a lot of
students are not understanding
if i ask you
what does one normality of hcl means
can you answer the question
well we know that
hcl is solute and water is solvent
in hcl there is only one hydrogen ion
and we know that the molar mass of
hydrogen is one gram
so this one normality means that
in one liter solution of hcl
only one gram has the capacity to react
let me repeat it
in one liter solution of hcl
only one gram has the capacity to
react so remember that molarity measures
that
how many moles of solute are present in
one liter solution
while normality measure that
how many grams equivalent of solutes are
present in one liter solution
now let me teach you that how can we
calculate normality
well find the normality of the solution
by dissolving 4 gram of h2s4 and 500 ml
water
here the given volume is 500 ml
i always convert it to liters
i divide 500 ml by thousand
i get 0.5 liter
secondly the given mass is 4 gram now we
need to convert this 4 gram to number of
grams equivalent of solute to do so we
follow three steps which we have already
learned in the previous slide we know
that the molar mass of h2so4 is 98 gram
here to calculate equivalent mass we
divide molar mass by x
here the molar mass is 98 gram and the
value of x is 2 because there are two
hydrogen ions
after calculation i get 49 gram
thirdly to find the number of grams
equivalent of solute
we divide given mass by equivalent mass
now the given mass is 4 gram and the
equivalent mass is 49 gram
after calculation
i get
0.0816 gram
lastly i calculate the normality
the formula of normality is
number of gram equivalent of solute
upon volume of solution in liter we know
that the number of gram equivalent of
solute is
0.0816 gram and the volume of solution
is 0.5 liter
i plug in these values in this equation
after calculation
i get
0.16 gram per liter
or 0.16 n
so the normality of this solution is
0.16
n
secondly let me teach you one another
numerical
calculate normality of the solution by
dissolving 10 gram of calcium hydroxide
and 300 ml water
here
the given volume is 300 ml
i convert it to liter by dividing it by
thousand
i get 0.3 liter
now i need to convert this 10 gram of
calcium hydroxide
to number of grams equivalent of solute
to do so i follow three steps
we know that the molar mass of calcium
hydroxide is 74 gram
secondly to find equivalent mass
i divide molar mass
by eggs
we know that molar mass is 74 gram and
the value of x is 2 because there are
two hydroxide ions
present in calcium hydroxide
after calculation
i get 37 gram
thirdly to calculate number of grams
equivalent of solute i divide given mass
by equivalent mass
we know that given mass is 10 gram and
the equivalent mass is 37 gram
so i plug in these values in this
equation
after calculation
i get
0.27 gram
lastly i calculate the normality of this
solution
the formula of normality is
number of grams equivalent of solute
upon volume of solution and later
the number of grams equivalent of solute
is 0.27
and the volume of the solution is 0.3
liter
after calculation i get
0.9 gram per liter or 0.9
so the normality of this solution is 0.9
now let me teach you one important
concept of normality and molarity which
is usually asked in mcqs
what is the normality of 2m
h3po4 solution
well this 2m means that the molarity of
h3po4 is 2 moles per liter or just 2m
now the relationship between normality
and molarity is
n is equal to m into x
we know that there are three hydrogen
ions present in
h3po4 so the value of x is three
and we already know that the value of m
is two
so i write n is equal to 2 and 2 3 our n
is equal to 6 n
so the normality of this solution is 6 n
just remember this relationship of
normality and molarity which is usually
asked in mcqs
finally let me teach you one advanced
numerical calculate the mass of h2so4
present in 200 ml of a binormal solution
remember that semi-normal solution means
1 upon 2 binormal solution means 2
centi-normal solution means 1 upon 100
etc in such type of numericals normality
is already given for example
2n
we know that normality is equal to
number of grams equivalent of solute
upon volume
here normality is 2 and we divide 200 ml
by thousand we get 0.2 liter
after calculation i get the number of
gram equivalent of solute is 0.4 gram
now i follow the three steps molar mass
of h2so4 is 98 gram secondly the
equivalent mass is
molar mass upon x
we know that molar mass is 98 gram and
the value of x is 2 after calculation i
get 49 gram
thirdly we know that number of moles of
solute is equal to given mass
upon equivalent mass
now listen carefully we have already
calculated
the number of gram equivalent of solute
which is 0.4 gram
secondly we have already calculated
equivalent mass which is 49 gram
now if i put these two values in this
equation
i can get the value of given mass which
is required so i put these two values in
this equation
after calculation
i get 19.6 gram so the given mass or the
required mass is 19.6 gram therefore
remember that the mass present in 200 ml
of h2so4 is
19.6 gram thus by this way we can easily
calculate the required mass if normality
is given
so this was all about normality
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