NEET-Chapterwise Test -

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REDOX TEST -01

Chemical Bonding

Haloalkanes &Haloarenes 1

Haloalkanes & Haloarenes 2

Alcohols,Phenols & Ether _1

IONS-CATION & ANIONS

IONS:-

Ionic Compounds composed of metals & non-metals contain charged species. The charged species are known as ions. Ions may consist of a single charged atom (Simple ions) or group of atoms that have net charge on them (Polyatomic ions)

An ion can be positively or negatively charged. Hence , ions are of two types

Types of ions:-

1) Cations- are ions with positive charge. The magnitude of positive charge is equal to number of electrons lost.

They are further categorized as:–

i)Univalent cation(Monovalent cations) – Carrying unit positive charge – Na⁺, H⁺ & K⁺ etc

M   - 1e^- à M⁺( Univalent cation  )

ii)Bivalent ions (Divalent) :- Carrying two unit positive charge:- Mg²⁺, Ca²⁺  & Ba²⁺ etc

M – 2e^- à M²⁺(Bivalent cation )

iii) Polyvalent ions :- Carrying more than two unit  positive charge :-

M – ne^-  à Mⁿ⁺

Trivalent Cations :- Al³⁺, Ga³⁺ & B³⁺

Tetravalent cations :- Pb²⁺, Sn⁴⁺ etc

2) Anions – are ions carrying negative charge. The magnitude of negative charge is equal to number of electrons gained

They are further categorized as:-  

i) Univalent anions – Carrying unit negative charge:- Cl^-, Br- & I^- etc

X + 1e - à X^-

ii) Bivalent(Divalent anions) :- Carrying two unit negative charge :- O²-, S^2- & SO₄^2- etc

X + 2e-  à X^2-

iii) Polyvalent anions:- Carrying more than two unit negative charge:- PO₄^3-  & BO₃^3-  etc

X +  3e^-  à X^3-

CATIONS:-		ANIONS
Suffix – IUM Na+( Sodium) K+(Potassium) Li+(Lithium) Rubidium(Rb+) Caesium(Cs+)  H3O+(Hydronium) Mg2+(Magnesium) Ca2+(Calcium) Ba2+(Barium) Strontium (Sr2+) Al3+(Aluminium ) Ga3+(Galium )	Suffix- OUS Fe2+( Ferrous) Hg+(Mercurous) Cu+(Cuprous) Pb2+(Plumbous) Sn2+(Stannous) SUFFIX- IC Ferric (Fe3+) Mercuric  (Hg2+) Cupric  (Cu2+) Plumbic ( Pb4+) Stannic  ( Sn4+)	Suffix –ate Carbonate – CO32- Bicarbonate- HCO3- Nitrate – NO3- Sulphate- SO42- Phsophate- PO43- Borate- BO33- Suffix – ite Nitrite – NO2- Sulphite-SO32-	Suffix – ide Fluoride- F- Chloride- Cl- Bromide- Br- Iodide- I- Hydroxide- OH- Oxide- O2- Sulphide-S2- Nitride  - N3- Hydride – H-

NOTE :-
Valency :- The combining power( or capacity) of an element is known as its valency
Valence electrons:- Number of electrons present in the valence shell ( or Outer most shell ) of an atom
Polyatomic ion :- are group of atoms carrying a net charge. They contain more than one type of element -as Phosphate ions- Contains O & P element , Sulphate ion( Contains S & O) , Bicarbonate ion ( Contain H,C& O ) etc
To be Continued .......

Electrochemical Cell

Electrochemical cell :-

• An electrochemical cell is a device that converts the chemical energy into electrical energy of a spontaneous redox reaction. (Definition ) 
• Here Gibbs free energy of the spontaneous redox reaction is converted into electrical work which may be used for running a motor or other electrical gadgets like geyser, fan , heater etc 
•  Electrochemical or Voltaic(galvanic) cells are of a type that produce electric current as a result of chemical reaction 
• Apparatus:- Electrochemical cell consists of -Two electrodes usually set up in two separate beakers. The electrolytes taken in the two beakers are different. The electrodes taken are of different materials. To set up this cell , a salt bridge/porous pot is used. 
• Sign Convention :- Anode (-ve pole) & cathode(+ve pole) 
• Cell Diagram :- 
  

  salt Bridge :- Necessity to use salt bridge 

• It is a U-shaped tube that contains a gel permeated with a solution of an inert electrolyte such as Sodium sulphate, potassium nitrate or potassium sulphate etc  . The ions of the inert electrolyte do not react with the other ions in the solution & they are not oxidised or reduced at the electrodes. The salt-bridge is necessary to complete the electrical circuit & to maintain electrical neutrality in both compartments ( by flow of ions) 

                                Representation of Electrochemical cell 

Chemical reaction involved in electrochemical cell

Facts :- 

1. If the external potential applied becomes greater than internal one then cell behaves as an electrolytic cell & thus the direction of flow of current is reversed 
2. The potential difference between the two electrodes of a galvanic cell is called cell potential & is measured in Volts.It is called emf of the cell when no current is drawn through the cell.
3. For Daniell cell, the cell potential is -1.1V . 
4. Ecell= Eright - E left
5. Measurement of electrode potential is done by using SHE( standard Hydrogen Electrode)