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Humidity

What is Humidity?

The simple meaning of humidity is ‘atmospheric moisture’ or ‘amount of water vapor in the atmosphere’.
what is humidity
 Humidity is the amount of water vapors present in the atmosphere (or air). Water vapors are the gaseous state of water and are invisible.
 Humidity can be measured by three ways that are: absolute, relative and specific.
    1.   Absolute humidity is the water content of air in the gram per cubic meter at a given temperature.
     2.   Relative humidity is expressed in percentage, and it measures the current absolute humidity relative to the maximum humidity for that temperature.
    3.   Specific humidity is expressed as the ratio of the mass of the water vapors to the total mass of moist air parcel.

What is Absolute Humidity?

To understand absolute humidity let’s assume you are standing in ground and you collect some air. Now you check that air volume in your chemistry lab and get accurate amount of water vapors in gram. If you collect 1 cubic meter of air volume and it contains 30 gram water vapors than absolute humidity of that ground air is 30 grams per cubic meter. So, now you answer this question i.e. what is absolute humidity.
Absolute humidity (AH) is defined as the total mass (in gram) of water vapor present in a given volume (in cubic meter) of air. Absolute Humidity changes with changes in air temperature and pressure. Absolute humidity is the mass of the water vapors( m H 2 O ) {\displaystyle (m_{H_{2}O})} divided by the volume of the air and water vapor mixture.
AH = m/V
Where, AH = Absolute humidity,
             m = mass of the water vapors( m H 2 O ) {\displaystyle (m_{H_{2}O})},
             V = volume of the air and water vapor mixture.


What is Relative Humidity?

To understand relative humidity let’s assume you are in a building where air absolute humidity is 15 grams per cubic meter at 25 degree Celsius temperature and at 25 degree Celsius temperature highest amount of water vapors is 30 grams per cubic meter (saturated air with water vapors 15 grams per cubic meter). So, now you can calculate relative humidity as follows:
Relative humidity = (15 grams per cubic meter / 30 grams per cubic meter)x100
                            RH = 50%
So, now you answer this question i.e. what is relative humidity.
Relative humidity (RH) is defined as the ratio of the partial pressure of water vapors to the equilibrium vapor pressure of water at a given temperature. If temperature of the atmosphere is lower than relative humidity is higher as cold air (air with low temperature) holds more water vapors (moisture) but, If temperature of the atmosphere is higher than relative humidity is lower as hot air (air with high temperature) holds less water vapors (moisture).

What is Specific Humidity?

To understand specific humidity let’s assume you have an air parcel (air volume or some amount of air) and this parcel contains 10 gram mass of water vapors and total mass of air is 1 kg (including mass of all gases present in air and mass of water vapors) than specific humidity is 10 gram per kilogram. So, now you answer this question i.e. what is specific humidity.
Specific Humidity is defined as the ratio of the mass of water vapors in air to the total mass of the mixture of air and water vapors.
Specific Humidity = mass of water vapor/total mass of air

Difference between Humidity and Relative Humidity

Before going to discuss about “Difference between Humidity and Relative Humidity” we need to understand that what is humidity and what is relative humidity. And to get answer of these two questions just read above paragraph once again if you don’t understand.
Humidity is the amount of water vapors present in the atmosphere (or air). Relative humidity is expressed in percentage, and it measures the current absolute humidity relative to the maximum humidity for that temperature.


What is Normality ?

What is Normality ?

 Normality is the ratio of gram equivalent weight to volume of solution in liter
where gram equivalent is the measure of reactive capacity of molecule consider for normality.

Normality (N) :- 

                                Gram equivalent weight  / Volume of the solution in liter.

Unit =>   N = "eq/L" (equivalent per liter)



Molarity vs Normality
What is Normality

What is Molality ?

What is Molality? 

It is the ratio of moles of substance to kilogram of solvent.
Where mole is weight in gram divided by molecular weight.
Molality is chemistry terminology.

Molality (m) :- 

                                No. of moles of the solute  Mass of solvent in Kilogram (Kg).
   
Unit =>   m = Moles/Kg
Molality Chemistry Infographics
What is Molality

YouTube Video on Molality and Molarity

Chemistry

What is Chemistry?

It is the branch of science which deals with the study of composition, properties and interaction of matter.

Definition of Chemistry

Chemistry is the scientific study of matter and substances for how they combine, separate, react or interact with each other.

Types of Chemistry

Chemistry is generally (as per basic chemistry) classified into three classes i.e. Physical chemistry, Organic chemistry and Inorganic chemistry. 

1. Physical Chemistry

Physical chemistry is the branch of chemistry. Physical Chemistry utilizes applications of physics to chemical systems to understand their physical properties.
Physical chemistry is the study of atomic, subatomic, macroscopic, microscopic or particulate phenomena in chemical systems in terms of different laws and concepts of physics. Physical chemistry applies the principles and concepts of physics such as thermodynamics, force, time, energy, motion, statistical mechanics, quantum chemistry, dynamics and equilibrium.
Physical properties of different type of chemical substances can be studied on different scales like atomic, subatomic, macroscopic and microscopic........ read more 

2. Organic Chemistry

Organic chemistry is a branch of chemistry which involve the scientific study of structure, properties & reactions of organic species, compounds or organic materials, means matter have various forms found that contains carbon atoms. Study of structure of organic chemistry compounds includes use of spectroscopy techniques like IR Spectroscopy, Microwave Spectroscopy, NMR Spectroscopy, Mass Spectroscopy, X – Ray Diffraction, Electron Diffraction, Neutron Diffraction and other physical and/or chemical type of methods to examine chemical composition and chemical constitution of the organic chemistry compounds and materials to be analysed. This is article on what is organic chemistry at “chemistry notes info blog”. Study of properties of organic compound includes study of both physical properties as well as chemical properties of organic chemistry compounds, which uses the similar methods and also methods to evaluate the chemical reactivity to understand behavior of organic matter (organic sample) in its pure form (if when possible), otherwise in solution, mixture forms. Study of chemistry of organic reactions includes the searching their possibility through use in the preparations of goal molecule or compounds like natural products, medicinal drugs, polymers, solvents, etc.) by their chemical synthesis, also focused on the study of  reactivity’s of the individual organic molecules.... read more 

3. Inorganic Chemistry

Inorganic chemistry is the branch of chemistry, which deals with the study of inorganic compounds and organo-metallic compounds. Inorganic chemistry includes study of all chemical compounds excluding organic compounds (where, organic compounds are carbon based compounds, generally having carbon-hydrogen bonds i.e. C-H bonds. 

Example of Inorganic Compound

Salt Magnesium Chloride (MgCl2) is an ionic Inorganic Compound which contains magnesium-cations Mg2+ and chloride-anions Cl

Branches of Inorganic Chemistry

Descriptive Inorganic Chemistry
Descriptive inorganic chemistry based on the arrangement and ordering of compounds based on their properties.

Coordination Chemistry

Coordination chemistry is the branch of Inorganic chemistry which deals with the study of coordination compounds or coordination complexes. A coordination compound or coordination complex contains of a central atom or ion, which is generally metallic and is known as coordination center, and get surrounded by group of bounding molecules or ions, these surrounding molecules and ions are known as ligands.

Materials Science

Material science deal with the study of materials. Study of metals, semiconductors, polymers, ceramics, nanomaterials, biomaterials and many other form of materials comes under material science. A material scientist........... read more 

4. Analytical Chemistry

Analytical Chemistry is the branch of chemistry deals with the study of material examination to separate out them into different components and identifying all components and how much these components present in material. There are different analytical methods and techniques to perform these tasks.

What is Analytical Chemistry ?

Analytical chemistry is all about, what an analytical chemist do in an analytical chemistry lab. And simply we can say that analytical chemistry is the branch of chemistry for qualitative analysis and quantitative analysis of compounds and mixtures by using different test methods and techniques like flame tests, chemical tests, precipitation... read more

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Physical Chemistry

Physical Chemistry


What is Physical Chemistry ?

Definition of Physical Chemistry- Physical chemistry is the branch of chemistry. Physical Chemistry utilizes applications of physics to chemical systems to understand their physical properties.

Physical chemistry is the study of atomic, subatomic, macroscopic, microscopic or particulate phenomena in chemical systems in terms of different laws and concepts of physics. Physical chemistry applies the principles and concepts of physics such as thermodynamics, force, time, energy, motion, statistical mechanics, quantum chemistry, dynamics and equilibrium.

Physical properties of different type of chemical substances can be studied on different scales like atomic, subatomic, macroscopic and microscopic.

Atomic

Atomic properties are properties related to atoms or elements. Atomic numbers, atomic weight, oxidation state, electron per shell, electronic configuration, and atomic radius are example of atomic properties.

Atomic Properties of Element Carbon

  • Chemical Symbol: C
  • Atomic Number: 6
  • Atomic Weight (Relative Atomic Mass), u (g/mol): 12.0107
  • Oxidation States: -4, +2, +4
  • Electrons Per Shell: K2 L4
  • Electronic Configuration: 1s22s22p2
  • Atomic Radius, pm: 67

Subatomic

Subatomic properties are properties related to study of subatomic particles and research on energy and waves. This is part of advanced physical chemistry or nuclear chemistry.

Microscopic

Microscopic properties are properties related to microscopic level like shape and structure of crystals and molecules with the use of light microscopes, electron microscopes, and scanning probe microscopes

Macroscopic

Macroscopic properties are properties of substances which describe how relatively large quantities of the substance behave as a group, for example melting points (M.P.) and boiling points (B.P.), vaporization and latent heats of fusion, specific heat capacity, thermal conductivity, coefficient of linear thermal expansion and many other physical properties.
For example water exist in three states i.e. Solid-Ice, Liquid-Water, Gas-Steam. When we cool steam it turns into water and on further cooling water convert into ice.

Branches of Physical Chemistry

Physical chemistry have many branches some of them are described below-

Electrochemistry

Electrochemistry is the branch of physical chemistry which deals with the studies of relationship between electricity and chemicals.

Photochemistry

Photochemistry is the branch of physical chemistry which deals with the chemical effects of light. Photo-Chemistry describes chemical reaction caused by absorption of ultraviolet radiation (wavelength from 100 to 400 nm), visible light (400 – 750 nm) or infrared radiation (750 – 2500 nm).

Thermochemistry

Thermochemistry is the branch of physical chemistry which deals with the study of the energy and heat associated with chemical reactions and physical transformations.

Spectroscopy

Spectroscopy is the branch of physical chemistry which deals with the study of the interaction between matter and electromagnetic radiation.

Chemical Kinetics

Chemical Kinetics is the branch of physical chemistry which deals with the study of rates of chemical processes. Chemical Kinetics is also known as Reaction Kinetics,

Quantum Chemistry

Quantum chemistry is the branch of physical chemistry which deals with the application of quantum mechanics in physical models and chemical systems. Quantum chemistry is also known as molecular quantum mechanics.

Surface Chemistry

Surface science is the branch of science which deals with the study of physical and chemical phenomena which occurs at the interface of two phases. Surface science includes the fields of surface chemistry and surface physics.

Solid-State Chemistry

Solid-state chemistry is the branch of physical chemistry which deals with the study of structure, synthesis, and properties of solid phase materials. Solid-state chemistry also known as materials chemistry.

Biophysical Chemistry

Biophysical chemistry is the branch of physical chemistry which deals with the uses of concepts of physics and physical chemistry for the study of biological systems.

10 Class- Periodic Classification of Elements

Periodic Classification of Elements

In year of 1800 about 30 elements were known but at present we know about 114 elements. All these elements have different properties. So to study about these elements easily, scientists start searching some patterns in the properties to arrange these elements.

Early Attempts in the Classification of Elements

                                                                   This is practice to arrange elements in order out of chaos, means arranging elements in group of metals and non-metals. Chaos means complete disorder or confusing. Furthermore attempts were made to achieve best classification of the elements.

Dobereiner’s Triads

                             A German chemist, Johann Wolfgang Dobereiner in 1817 tried to arrange elements in the group of 3-elements in each group with similar properties and he called these groups as ‘Triads’. Dobereiner shows that when we take any triad and arrange its elements in the order of increasing atomic masses then the atomic mass of the middle element in the triad is roughly equal to the average of the 1st and 3rd element of the triad.

Dobereiner Triads

Li
Na
K
Ca
Sr
Ba
Cl
Br
I
In first triad Li, Na, K atomic mass of   Na (23) = [ Li(7) + K(39)]/2

Newlands Law of Octaves

                                      An English scientist, John Newlands in 1866 arranges known elements in order of their increasing atomic masses. At that time he started with Hydrogen as 1st element with lowest atomic mass and ended at Thorium as 56th element.  John Newlands observe that the property of every eighth element  is similar to that of first element and compare this to octaves of music so he called it ‘Law of Octaves’ and this is known as ‘Newlands Law of Octaves’.

Newlands Octaves

H
Li
Be
B
C
N
O
F
Na
Mg
Al
Si
P
S
Cl
K
Ca
Cr
Ti
Mn
Fe
Co and Ni
Cu
Zn
Y
In
As
Se
Br
Rb
Sr
Ce and La
Zr
-
-

1.     Newlands law of octaves is applicable only up to Calcium and after Calcium it is not applicable because after Calcium every eighth element is do not similar to that of first element. 
2.     Newlands assumed only 56 elements exists in nature but later several elements discovered whose properties are very different to get fit in Newlands law of octaves. 
3.     With the discovery of new elements, Newlands try to fit these elements in octaves so he put two elements in same slot and Newland also put elements with different properties in same slot for example Co and Ni placed in F, Cl column.

Mendeleev’s Periodic Table

                                      A Russian chemist, Dmitri Ivonovich Mendeleev in 1872 published his ‘Mendeleev Periodic Table’ in a German journal.  He arranges elements in the form of table on the basis of fundamental property of elements i.e. atomic mass and also on the basis of similarity of chemical properties of elements, means elements with similar chemical properties are placed together in table.

Mendeleev Periodic Law

                             According to this law “the properties of elements are the periodic function of their atomic masses”.
In Mendeleev periodic table horizontal rows are called as ‘Periods’ and vertical columns are called as ‘Groups’.

Mendeléev’s Periodic Table

10th Class- Mendeleev periodic table, Periodic Classification of Elements Xth Class Chemistry Notes Part-1

Achievements of Mendeléev’s Periodic Table

                                                          Mendeléev’s Periodic Table contains some gaps but Mendeléev predicted that these gaps are filled by elements discovered in future. And named these undiscovered elements by placing eka (one) as a prefix to the name of preceding element of the same group. For example Gallium discovered later but Mandeleev predict it as Eka-Aluminium.
Properties of Eka-Aluminium and Gallium
Property
Eka-Aluminium
Gallium
Atomic Mass
65
69.7
Formula of Oxide
E2O3
Ga2O3
Formula of Chloride
ECl3
GaCl3
This prediction of Mandeleev proves correctness and usefulness of Mendeléev’s Periodic Table. Another achievement of Mandeleev is that many scientists now recognize him as originator of the concept on which periodic table is based and also when inert gases (means Nobel gases like He, Ne, Ar) are discovered, they are placed in separate column without disturbing existing order of elements.

Limitation of Mandeleev Classification

                                                These given below are the limitation of Mandeleev Classification. 
1. Position of Hydrogen- No fixed position given to Hydrogen as it behaves like both alkali metals and halogens. Like alkali, Hydrogen react with halogen oxygen and sulphur and also like halogen, Hydrogen exist in diatomic form and react with metals and non-metals. 
2. Isotopes- Isotopes have similar chemical properties but different atomic masses, so Isotopes are challenge to Mandeleev Periodic Law. 
3. Prediction of New Elements- Atomic masses of elements do not increase in regular manner so we cannot predict how many elements can be discovered between two elements.
Modern Periodic Table

                             Henry Moseley in 1913, after performing many experiments proves that atomic number is more fundamental property than atomic mass of an element. So he prepare periodic table on the basis of atomic number means elements are arranged in the order of increasing atomic number in Modern Periodic Table.

Modern Periodic Law

                             According to this law “the properties of elements are the periodic function of their atomic number”.
In Modern Periodic Table limitation of Mandeleev Classification are removed. 

Modern Periodic Table

moseley modern periodic table


Position of Elements in Modern Periodic Table

                                                          Modern Periodic Table contains 18 vertical columns (means 18 Groups) and 7 horizontal rows (means 7 Periods).
In Group- Elements in a group have same number of valence electrons means identical outershell electronic configuration, but as we move downside in a group number of shells increases.
In Period- Elements in a period have same number of shells. Also as we move from left to right in a period, atomic number increases by one unit so number of valence shell electrons also increases by one unit.

Trends in the Modern Periodic Table

Valency

          Number of valence electrons in outer most shell of any atom is called valency of that atom. As we move from left to right in a period, atomic number increases by one unit so valence electrons also increases by one unit but in a group it remains constant.

Atomic Size

                   Atomic size is determined by atomic radius.
In a Period- Atomic radius decreases as we move from left to right in a period, because as we move from left to right in a period Nuclear Charge (+ve) increases which pulls electrons (-ve) towards nucleus result in decreasing atomic size or decrease atomic radius.
In a Group- Atomic radius increases as we move from top to bottom in a group, because new shells are added which increases distance between nucleus and outermost electrons.

Metallic and Non-metallic Properties

                                                Elements towards left hand side in periodic table are metals while elements towards right hand side in periodic table are non-metals. Elements which separate metals and non-metals have the properties of the both metals and non-metals are known as Metalloids or Semi-Metals.

Example of Metals- Na, Mg, Al, Fe

Example of Non-metals- S, Cl, F, Br

Examples of Metalloids or Semi-Metals- B, Si, Ge, As, Sb, Te, Po

In a Period- Metallic character decreases and Non-metallic character increases as we move from left to right in a period because tendency to lose valence electrons  decreases due to increasing nuclear charge as we move from left to right in a period.
In a Group- Metallic character increases and Non-metallic character decreases as we move from top to bottom in a group because tendency to lose valence electrons increases due to increasing valence shells (i.e. increasing distance between nucleus and outermost electron) on moving from top to bottom in a group.
Metals are electropositive as they forms bonds by loosing electrons while Nonmetals are electronegative as they forms bonds by gaining electrons.
In general cases, oxides of metals are basic in nature while oxides of non-metals are acidic in nature.
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