Use Coupon: CART20 and get 20% off on all online Study Material

Total Price: R

There are no items in this cart.
Continue Shopping
Get instant 20% OFF on Online Material.
coupon code: MOB20 | View Course list

Get extra R 650 off


wht is oxidation no. ??? how to find it ???? is algebraic method applicable in complex molecules    apart frm ur dtailed ans if u hav any link for REDOX REACTN plzzz send.......

6 years ago


Answers : (1)


Dear raj,

Electrochemical reactions involve the transfer of electrons. Mass and charge are conserved when balancing these reactions, but you need to know which atoms are oxidized and which atoms are reduced during the reaction. Oxidation numbers are used to keep track of how many electrons are lost or gained by each atom. These oxidation numbers are assigned using the following rules:

  1. The convention is that the cation is written first in a formula, followed by the anion.

    For example, in NaH, the H is H-; in HCl, the H is H+.


  2. The oxidation number of a free element is always 0.

    The atoms in He and N2, for example, have oxidation numbers of 0.


  3. The oxidation number of a monatomic ion equals the charge of the ion.

    For example, the oxidation number of Na+ is +1; the oxidation number of N3- is -3.


  4. The usual oxidation number of hydrogen is +1.

    The oxidation number of hydrogen is -1 in compounds containing elements that are less electronegative than hydrogen, as in CaH2.


  5. The oxidation number of oxygen in compounds is usually -2.

    Exceptions include OF2, since F is more electronegative than O, and BaO2, due to the structure of the peroxide ion, which is [O-O]2-.


  6. The oxidation number of a Group IA Element in a compound is +1.


  7. The oxidation number of a Group IIA Element in a compound is +2.


  8. The oxidation number of a Group V11A Element in a compound is -1, except when that element is combined with one having a higher electronegativity.

    The oxidation number of Cl is -1 in HCl, but the oxidation number of Cl is +1 in HOCl.


  9. The sum of the oxidation numbers of all of the atoms in a neutral compound is 0.


  10. The sum of the oxidation numbers in a polyatomic ion is equal to the charge of the ion.

    For example, the sum of the oxidation numbers for SO42- is -2.

Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.

All the best.

Win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar  respectively : Click here to download the toolbar..


Askiitians Expert

Sagar Singh

B.Tech, IIT Delhi

6 years ago

Post Your Answer

Other Related Questions on Physical Chemistry

Current of 10 ampere is passed through solution of CuSO4 for 32 min 10 sec.If 896 ml of Oxygen is liberated at STP then what will be efficiency of the cell.
Dear Candidate, I already answered this qstn. plz check this below: from faraday’s law, moles x valence factor = i*t/F moles = i*t/F*n = 10*1930/2*96485 = 0.100 approx. Moles given at STP = ...
Vikas TU 25 days ago
first and second ionization energies of magnesium are 5.7 and 15.035eV the amount of energy in kJ needed to convert all the atoms of magnesium into mg+2 ions present in magnesium vapours is
Mg -------> Mg+ + e- I.E1= 5.7 eV. Mg+ --------> Mg2+ + e- I.E.2 = 15.035 eV. For Mg to Mg2+ the eqns. would be Mg -----------> Mg2+ + 2e- adding the I.E1 AND IE2 eqns. We get, the final...
Vikas TU 25 days ago
The molar volumes of ice and water are 0.0196 and 0.0180 litres per mole at 273K. If ΔH for the transition of ice to water is 1440 calories per mole at 1 atm pressure, find ΔU.
From eqn. ΔU + Δ(PV) ΔH = = ΔU + ΔPV + PΔV Given, 1440 = ΔU + 0.0196*273 + 0.0180*273 ΔU = 1440 – 10.2648 = 1429.73 calories.
Vikas TU 25 days ago
@ DEEPAK THERE ARE many methods which are used in organic chemistry for the purification of the compound , kindly let me know which one u want to know in detail . there are methods like...
Umakant biswal one month ago
sir please explain that Why CHCl3is more acidic than CHF3 ?
Hi !Raju , cl 3 c - is less basic than F 3 c - because florine can disperse charge only by an inductive effect while cl(having 3d orbitals) disperses charge by inductive effect as well as...
nath 2 months ago
@ raju chf3 when it will be separate into its ions then it will generate cf3- and h+ and chcl3 when it will dissociate into ions , it will generate ccl3- and h+ . cf3- is not stable by...
Umakant biswal one month ago
Which of the following is not true for PCl 5 (a)Its three P-Cl bond lenghts are equal (b)It involves sp 3 d hybridization. (c)It has regular geometry. (d)Its shape is trigonal bipyramidal....
@ mudit i am sorry , all the four statement are actually correct , so, none of them will be false . in the frst statement it state that – 3 of the bonds are equal – thats true ,. three...
Umakant biswal one month ago
THe answwer given in book is ©.I think it is incorrect but want to make it sure so waiting for more answers.
Mudit one month ago
@ mudit option no a turns out to be the correct answer , as in pcl5 , all the bonds are not equal while 3 of them are equal and the rest 2 p-cl bonds are actually greater than these 3 . and ...
Umakant biswal one month ago
View all Questions »

  • Complete JEE Main/Advanced Course and Test Series
  • OFFERED PRICE: R 15,000
  • View Details
Get extra R 3,750 off

Get extra R 650 off

More Questions On Physical Chemistry

Ask Experts

Have any Question? Ask Experts

Post Question

Answer ‘n’ Earn
Attractive Gift
To Win!!!
Click Here for details