How to calculate normmality in chemistry?

Summary

This 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

00:00

🧪 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.

05:02

📚 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.

10:03

🔍 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.

15:04

📉 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.

20:05

📝 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.

Keywords

💡Normality

Normality is a measure of concentration in a solution, defined as the number of gram equivalents of solute dissolved in one liter of solution. It is central to the video's theme as it is used to explain how to calculate the reactive capacity of different substances in a solution. For example, the script discusses calculating the normality of an HCl solution by considering the equivalent mass of the solute and the volume of the solution.

💡Equivalent Mass

Equivalent mass is the mass of a substance that will either produce or react with one gram of hydrogen. It is a key concept in the video, explaining how the reactive capacity of a molecule is measured. The script uses the example of H2SO4, where the equivalent mass is calculated by dividing the molar mass by the number of hydrogen atoms that can dissociate, which is 2 in the case of sulfuric acid.

💡Molarity

Molarity is the amount of solute dissolved in a given volume of solution, typically expressed in moles per liter (M). It is introduced in the script as a comparison to normality, with the video emphasizing that molarity measures moles of solute, whereas normality measures the reactive capacity in terms of gram equivalents. An example provided is a 2M H3PO4 solution, where the normality is calculated based on the number of hydrogen ions that can dissociate.

💡Dissociation

Dissociation refers to the process where a compound separates into ions when dissolved in a solvent, like water. The script explains the dissociation of HCl into hydrogen and chloride ions and sodium hydroxide into sodium and hydroxide ions, which is fundamental to understanding how equivalent mass and normality are determined.

💡Ionization

Ionization is similar to dissociation and is used interchangeably in the script to describe how acids and bases break down into ions in water. It is crucial for understanding how the concentration of ions affects the calculation of normality and equivalent mass.

💡Molar Mass

Molar mass is the mass of one mole of a given substance, typically expressed in grams per mole. It is a fundamental concept in the script used to calculate equivalent mass. For instance, the molar mass of H2SO4 is given as 98 grams per mole, which is then used to find the equivalent mass by considering the number of dissociable hydrogen ions.

💡Gram Equivalent

Gram equivalent is synonymous with equivalent mass or equivalent weight in chemistry. It represents the amount of a substance that will either produce or react with a certain amount of another substance, usually hydrogen or oxygen. The script explains how to calculate the gram equivalent of substances like HCl and NaOH by using their molar mass and the number of reactive ions.

💡Reactive Capacity

Reactive capacity, as explained in the script, is the ability of a substance to participate in a chemical reaction, measured by equivalent mass. It is used to illustrate the concept that not all mass in a mole of a substance may be reactive, as in the example of H2SO4 where only 49 grams out of 98 grams have the capacity to react.

💡Acids and Bases

Acids and bases are types of chemical compounds that donate or accept protons (hydrogen ions) in a solution. The script uses the dissociation of HCl (an acid) and sodium hydroxide (a base) to explain the concepts of ionization and the calculation of normality and equivalent mass.

💡Solute and Solvent

In the context of the script, a solute is the substance that is dissolved in a solvent to form a solution. The solvent is typically a liquid, such as water, in which the solute is dissolved. The video discusses how the concentration of the solute, in terms of molarity or normality, affects the properties of the solution, using HCl and sodium hydroxide as examples.

💡Numericals

Numericals in the script refer to the step-by-step calculations and examples provided to illustrate the concepts of normality and equivalent mass. They are integral to the video's educational content, helping viewers understand how to apply theoretical concepts to practical chemical calculations, such as finding the normality of an H2SO4 solution.

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