What is Electrolysis? Animation

https://www.adichemistry.com/physical/electrochemistry/electrolysis/electrolysis.html

Electrolysis Animation at: https://youtu.be/8dPdrDIVWPI

Electrolysis definition:  It involves dissociation (lysis) of an electrolyte by using a direct electric current.  In this process, an electromotive force is employed to carry out a non-spontaneous redox chemical reaction in an electrolytic cell using proper electrodes. 

On this page, you will learn what is electrolysis used for in chemistry, what are electrodes, electrolytic cell construction, and about electrolysis reactions.

• What is an electrolytic cell?
• What are electrodes-cathode & anode?
• Types of Electrodes – Inert electrodes – Active electrodes
• Electrolysis reactions
• Electrolysis Examples
• Electrolysis solved questions IIT JEE NEET
• Applications of electrolysis

ELECTROLYTIC CELL

What is an electrolytic cell?

An electrolytic cell is used to perform electrolysis. It is provided with two electrodes, that are connected to different ends of the DC electric source. The electrode connected to the positive end is referred to as anode and that which is connected to the negative end is referred to as the cathode. 

What are electrodes?

Electrodes help in the conduction of electrons into and out of the cell as well as provide the surface for electrode reactions.

What are electrodes made of?

They are made up of electric conductors like metals or graphite. They may be in the form of rods or as a surface coating on the rods of other material or as a coating on the inside surface of the electrolytic cell.

In general platinum and graphite are used in making electrodes. They are inert and do not participate in the electrolysis reactions. However, the former is very costly while the latter is cheaper.

In the electrolytic cell, the anode is denoted by a positive sign while the cathode is denoted by a negative sign.

These signs are reversed in case of Galvanic cells.

However, one should keep in mind that irrespective of whether it is an electrolytic cell or a galvanic cell, at the anode, an oxidation half reaction takes place while at the cathode the other half-reaction – reduction occurs.

Types of electrodes?

The electrodes may be divided into two types depending on how they are involved in the electrolytic process.

i.e.

i) Inert electrodes – which do not enter into the electrolytic chemical reactions. The electrodes made up of Noble metals like platinum are used as inert electrodes.

ii) Active electrodes – which take part in the reactions of electrolysis. These are either dissolved into the electrolyte or a substance is deposited on them.

The cell is filled with the melt or the aqueous solution of the electrolyte and is subjected to potential differences sufficient to drive the electrolysis. The electrolyte is the substance that furnishes free ions either in the molten state or in the aqueous medium.

https://www.adichemistry.com/physical/electrochemistry/electrolysis/electrolysis.html

Best CSIR NET Chemistry study material – AdiChemistry

You will find the best study material for CSIR NET chemistry also useful to GATE chemistry as well as SET chemistry exams for JRF and assistant professor posts can be found at AdiChemistry. It is prepared by well-known author Aditya Vardhan from Warangal. More than 10000 students got benefit from this material. Most of them are at very high positions.

There are currently two books

1. Selected and important topics for CSIR NET GATE chemistry exams
2. Solved problems in Advanced Organic Chemistry

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 Selected & Important Topics for CSIR NET GATE SET in chemistry

Salient features
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Solved problems in Advanced Organic Chemistry

Salient features
* Detailed solutions to advanced organic problems from previous CSIR NET, GATE & SET examinations
* Number of solved problems: 226
* Free online access to 50+ online organic modules with extra 200+ practice questions (conditions apply)
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Drop an email to adichemadi@gmail.com to know “How to pay?” and other details.

 COMBO OPTION

The combo option includes both of the following books,

1. Important & selected topics for CSIR NET GATE SET + free access to online key / solutions
2. Solved problems in organic chemistry + access to online organic modules

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CSIR UGC COMBINED NATIONAL ELIGIBILITY TEST (CSIR UGC NET) for RESEARCH FELLOWSHIP & LECTURESHIP for chemical sciences is conducted twice every year (in June & in December) to select right candidates to award research fellowships, initially for two years (JRF) which can be further extended for three more years (SRF). This exam is also popularly known as CSIR NET or CSIR UGC NET exam. Most of the admissions into Ph.D courses in prestigious institutions of India like IISc, Central University of Hyderabad, IIT’s and several CSIR laboratories require the qualification in CSIR UGC NET exam.

 

CSIR NET GATE SET IIT JAM Chemistry study material – Aditya vardhan

High-quality study material and solved question bank for CSIR NET GATE SET IIT JAM exams in easily downloadable pdf format is available at https://www.adichemistry.com/common/htmlfiles/csir-gate-chemistry.html .

Written by famous Chemistry Guru: V. Aditya Vardhan, this study material is one of the best and is available at a reasonable price.

The logic of cracking CSIR NET & GATE exams is to adopt the smart reading of selected topics and avoid reading the entire syllabus. To address this, he compiled a book “Selected topics for CSIR NET GATE SET exams in chemical sciences”. It is useful to all the students of all branches of chemistry equally. It is a must reading book if you want to get a good rank in the above-said exams.

Another book “Solved problems in organic synthesis” is for those who are from organic specialization. Each question from advanced organic chemistry is explained in a lucid style.

One can also try the above books for their success in SET or SLET exams in various states of India. Like Kerala SET, AP SET, Telangana SET, MAHARASHTRA SET….. etc.

Also, you will find free material available for evaluation purpose on http://www.adichemistry.com/

 

Ionization energy basics and advanced concepts

Basics and advanced concepts of Ionization energy at: http://www.adichemistry.com/general/periodictable/ip/ionization-energy.html

Energy is required to overcome the attraction between nucleus and the electron while removing it from the atom. This energy is referred to as ionization energy and is expressed in kJ mol^-1. It is a measure of nuclear attraction over the outermost electron in a given species (atom or ion or molecule).

Previously it was denoted by ionization potential expressed in eV atom^-1. Physicists still follow this convention.

The ionization of an atom or an ion or a molecule (by removing electron) results in a positively charged species and is always an endothermic reaction i.e. energy is absorbed. Therefore, the enthalpy of ionization is a positive quantity.

More at: http://www.adichemistry.com/general/periodictable/ip/ionization-energy.html

FACTORS AFFECTING IONIZATION ENERGY

1) Atomic radius:

It is easy to recognize that the force of attraction between nucleus and electron decreases with increase in the distance between them. As a consequence, the  ionization energy decreases with increase in atomic radius since the nuclear attraction over outer electron decreases. Thus farther the electron from nucleus, easier will be the removal.

E.g., Down the group, the ionization energies decrease with increase in atomic radii.

Order of ionization energies in IA group ——->  Li > Na > K > Rb > Cs > Fr

2) Effective nuclear charge:

Ionization energy increases with increase in the effective nuclear charge. It is evident from the trend observed in first and second ionization potentials.

Effective nuclear charge refers to the nuclear attraction experienced by the electron. It is proportional to the number of protons per electron (i.e. ratio of protons to electrons).

 

3) Shielding or screening effect:

Reduction in nuclear attraction over the outer electrons due to repulsions by inner electrons is called screening or shielding effect.

Ionization energy decreases with increase in screening power of inner electrons.

The order of screening power of electrons present in different types of orbitals is: s > p > d > f .

4) Penetration power:

The ability of an electron to come closer towards nucleus is called penetration power. Electrons will have the natural tendency to come closer towards the nucleus. However, the time they spend closer to the nucleus depends on the shape of orbital as well as the principal quantum number.

Greater the penetration power, greater will be the ionization energy.

The order of penetration power of electrons in different orbitals is as follows.

s > p > d > f

5) Electronic Configuration:

Atoms with stable electronic configurations like: ns² np⁶ or half filled or completely filled sub shells are extra stable. Removal of electrons from them is difficult and hence their ionization energies are comparatively high.

These configurations are more symmetric and the exchange energy is minimal. Hence they are relatively more stable.

E.g. Noble gases with ns² np⁶ ; IIA group elements with ns² (completely filled); and VA group elements with ns² np³ (half filled) configurations have higher ionization potentials.

More at: http://www.adichemistry.com/general/periodictable/ip/ionization-energy.html

Ionic strength – solved problems – AdiChemistry – IIT JAM JEE NEET

Quick video presentation on Ionic strength through solved problems – supplementary to Debye-Huckel’s theory.

https://youtu.be/U54DQz36-O4

You will find how solve following problems in above video.

1) Identify, from the following, the correct ionic strengths for (A) 0.01 molal solution of NaCl and (B) a 0.01 molal solution of Na2SO4. (CSIR NET JUNE 2013)
1) A) 0.010 mol kg-1 B) 0.010 mol kg-1 2) A) 0.010 mol kg-1 B) 0.025 mol kg-1
3) A) 0.010 mol kg-1 B) 0.030 mol kg-1 4) A) 0.010 mol kg-1 B) 0.015 mol kg-1

2) The ionic strength of a solution containing 0.008 M AlCl3 and 0.005 M KCl is:
(CSIR NET DEC 2016)
1) 0.134 M 2) 0.053 M 3) 0.106 M 4) 0.086 M

Also visit: http://www.adichemistry.com/

Hybridization sp sp2 sp3 sp3d sp3d2

What is hybridization?

The intermixing of two or more pure atomic orbitals of an atom with almost same energy to give same number of identical and degenerate new type of orbitals is known as hybridization.

The new orbitals formed are also known as hybrid orbitals.

Almost always, some sort of intermixing i.e., hybridization of pure atomic orbitals is observed before the bond formation to confer maximum stability to the molecule. You can find selected illustrations of different types of hybridizations in the following sections.

JUMP TO EXAMPLES OF SP HYBRIDIZATION

JUMP TO EXAMPLES OF SP² HYBRIDIZATION

JUMP TO EXAMPLES OF SP³ HYBRIDIZATION

Wilkinson’s catalyst – for CSIR NET GATE IIT JAM chemistry exams

RhCl(PPh₃)₃ – Chlorotris(triphenylphosphine)rhodium(I), is known as Wilkinson’s catalyst. It is used as a homogeneous hydrogenation catalyst. It is a square planar 16-electron complex. The oxidation state of Rhodium in it is +1.

FIND MORE INFORMATION AT

http://www.adichemistry.com/inorganic/organometallic/catalysis/wilkinson/wilkinsons-catalyst.html

 

Indeed, Wilkinson’s catalyst is a pre-catalyst that is converted to an active form by losing one triphenylphosphine ligand before entering the catalytic cycle. Usually, the solvent molecule fills the vacant site.

Initially, the catalyst activates the molecular dihydrogen by oxidative addition mechanism to give a 18 valence electron dihydrido complex. The oxidation state of Rh is increased to +3. Thus formed dihydrido complex binds to the olefin in the next step with the concomitant loss of solvent or PPh₃ ligand. Since the activation of dihydrogen occurs before addition of olefin, this path is referred to as dihydride path .

Now one of the hydrogen undergoes migratory insertion at the double bond. This is a slow step i.e., Rate Determining Step (RDS).

Immediately and finally, the alkane is released rapidly by an irreversible reductive elimination step that completes the catalytic cycle. The oxidation state of Rh is decreased to +1 and the catalyst is regenerated.

Physical Chemistry

Physical chemistry deals with the basic principles of physical science involved in chemical systems. It often deals with the macroscopic side of chemical systems; like inter molecular forces, thermodynamic properties, chemical equilibria, reaction kinetics and electrochemical processes.

However modern physical chemistry also deals with the principles of quantum mechanics to help in understanding the chemical phenomena at atomic and molecular level.

On the following page you can find links to topics in physical chemistry.

http://www.adichemistry.com/physical/physical-chemistry.html

 

IIT JEE 2015 solved question paper

Find step wise interactive solutions to: IIT JEE 2015 main in chemistry subject at: http://www.adichemistry.com/jee/free/paper/main/2015/index.html. It is also equally helpful to NEET aspirants.

 

Sample questions:

 

 

The ionic radii (in Å) of N^3-, O^2- and F^– are respectively:

(1) 1.36, 1.40 and 1.71
(2) 1.36, 1.71 and 1.40
(3) 1.71, 1.40 and 1.36
(4) 1.71, 1.36 and 1.40

 

The synthesis of alkyl fluorides is best accomplished by :

(1) Free radical fluorination
(2) Sandmeyer’s reaction
(3) Finkelstein reaction
(4) Swarts reaction

FACTORS AFFECTING RATE OF A CHEMICAL REACTION

Factors that influence the reaction rates of chemical reactions include :

1) Concentration of reactants

2) Pressure

3) Temperature

4) Catalyst

5) Nature of reactants

6) Orientation of reacting species

7) Surface area

8) Intensity of light

9) Nature of solvent

According to the collision theory, the rate of a reaction is directly proportional to the number of effective collisions per second between the reactant molecules. Rate of a reaction is directly proportional to the concentration of reactants.

i.e. rate (r) ∝ cⁿ 

where

c = concentration

n = order of the reaction

or r = kcⁿ 

where

k = specific rate

Explanation: The number of collisions and hence the activated collisions between the reactant molecules increase with increase in concentration. Therefore, according to the collision theory, the rate of a reaction should increase with increase in the concentration since the rate is directly proportional to the collision frequency.

 

MORE AT

http://www.adichemistry.com/physical/kinetics/factors/factors-affecting-rate-reaction.html