<< Chapter < Page Chapter >> Page >

Normality(n)

Normality is a measure of concentration of solution. It compares solute in terms of gram equivalents to the volume of solution in litres.

Normality(N) = geq V L

Its unit is geq/ litres. In case we consider volume in ml i.e. cc, then the expression of normality is given as :

Normality(N) = geq V C C X 1000 = milli-gram equivalent V C C = meq V C C

If volume of a solution of known normality is known, then number of gram equivalents or milli-gram equivalents of solute are obtained as :

geq = N V L

meq = N V C C

It is evident from the definition of normality that normality of a given bulk solution and that of a sample taken from it are same. For example, if we take 10 cc of sulphuric acid from 1 litre of 0.2N sulphuric acid solution, then normality of sample taken is also 0.2N. However, geq or meq will be different as the amount of solutes are different.

meq in bulk solution = 0.2 X 1000 = 200

meq in sample = 0.2 X 10 = 2

Problem : Find volume of 0.2 N solution containing 2.5 meq of solute.

Solution : The gram equivalent is given by :

meq = N V C C

V C C = meq N = 2.5 0.2 = 12.5 c c

Problem : How many grams of wet NaOH containing 10% water are required to prepare 1 litre of 0.1 N solution.

Solution : We can determine amount of NaOH for preparation of 1 litre of 0.1 N solution by using normality relation :

g e q = N V = 0.1 X 1 = 0.1

g e q = g E = x g M O

The molecular weight of NaOH is 23+16+1= 40. Its valence factor is 1. Hence,

g = geq X M O x = 0.1 X 40 1 = 4 g m

But 100 gms of wet NaOH contain 88 gm NaOH. Applying unitary method, 4 gm of NaOH is present in wet NaOH given by :

Mass of wet NaOH = 4 X 100 88 = 4.55 g m

Problem : Borax ( N a 2 B 4 O 7 , 10 H 2 O ) is a strong base in aqueous solution. Hydroxyl ions are produced by ionic dissociation as :

2 N a + + B 4 O 7 2 - + 7 H 2 O 4 H 3 B O 3 + 2 N a + + 2 O H

A solution of borax is prepared in water. The solution is completely neutralized with 50 ml of 0.1N HCl. Find the mass of borax in the solution. Consider atomic weight of boron 24 amu.

Solution : Applying gram equivalent concept,

meq of borax = meq of 50 ml 0.1N HCl

meq of borax = N V = 0.1 X 50 = 5

Now, gram equivalent is connected to mass as :

m e q = 1000 g E = 1000 x g M O

g = m e q X E 1000 x = 1000 x g M O

Molecular weight of borax is 2X23 + 4X24 + 7X16 + 7X18 = 380. The valence factor of borax is 2 as one molecule of borax gives 2 hydroxyl ions. Putting values, we have,

g = 5 X 380 1000 X 2 = 0.95 g m

Relation between normality and molarity

Normality is defined as :

Normality(N) = geq V L

Substituting for gram equivalent,

Normality(N) = geq V L = x M O V L

where “x” is valance factor. Now, molarity is defined as :

M = M O V L

Note that we have used the convention that “M” represents molarity and “ M O ” or subscripted symbol " M N H 3 " represents molecular weight. Now, combining two equations, we have :

N = x M

Normality = valance factor X Molarity

Combining solutions of different normality

Let us consider two solutions : 100 ml of 1 N H 2 S O 4 and 50 ml of 0.5 N H 2 S O 4 . What would be the normality if these two volumes of different normality are combined?

In order to determine normality of the final solution, we need to find total milli-gram equivalents and total volume. Then, we can determine normality of the final solution by dividing total gram equivalents by total volume. Here,

meq 1 = N 1 V 1 = 1 X 100 = 100

meq 2 = N 2 V 2 = 0.5 X 50 = 25

Total meq is :

meq = meq 1 + meq 2 = 100 + 25 = 125

Now, important question is whether we can combine volumes as we have combined milli-gram equivalents. Milli equivalents can be combined as it measures quantity i.e. mass of solutes, which is conserved. Can we add volumes like mass? Density of 1N solution has to be different than that of 0.5N solution. We need to account for the density of the individual solution. It means that given volumes can not be added. However, concentrations of these solutions are low and so the difference in densities of solutions. As a simplifying measure for calculation, we can neglect the minor change in volume of the resulting solution. With this assumption,

Total volume = V 1 + V 2 = 100 + 50 = 150 m l

The normality of the resulting solution is :

N = 125 150 = 5 6 = 0.83

Normality of combination of different acids

Normality is based on the concept of gram-equivalent, which, in turn, depends on equivalent weights. The equivalent weight, on the other hand, is obtained by dividing molecular weight by basicity. The basicity, in turn, is equal to numbers of furnishable hydrogen ions. We may conclude that gram equivalent is amount of acid per furnishable hydrogen ion. Thus, we can see combination of acids (like sulphuric and hydrochloric acids) in terms of their ability of furnishing hydrogen ions. What it means that we can add gram equivalents of two acids to find total gram equivalents and find normality of resulting solution.

We can extend the concept to basic solution as well.

Problem : 500 ml of 0.5 N HCl is mixed with 20 ml of H 2 S O 4 having density of 1.18 gm/cc and mass percentage of 10. Find the normality of resulting solution assuming volumes are additative.

Solution : Here, we first need to find normality of H 2 S O 4 solution, whose density and mass percentage are given. Now, molarity of the solution is given as :

M = 10 y d M O = 10 X 10 X 1.18 98 = 118 / 98 = 1.2 M

Normality of sulphuric acid solution is :

N = x M = 2 X 1.2 = 2.4 N

We can now determine total gram equivalents and total volumes to determine the normality of resulting solution.

meq 1 = N 1 V 1 = 0.5 X 500 = 250

meq 2 = N 2 V 2 = 2.4 X 20 = 48

Total meq is :

meq = meq 1 + meq 2 = 250 + 48 = 298

Total volume = V 1 + V 2 = 500 + 20 = 520 m l

The normality of the resulting solution is :

N = 298 520 = 0.57

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Stoichiometry. OpenStax CNX. Jul 05, 2008 Download for free at http://cnx.org/content/col10540/1.7
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Stoichiometry' conversation and receive update notifications?

Ask