What is Redox reaction: Definition and 50 Discussions

Redox (reduction–oxidation, pronunciation: RED-oks or REE-doks) is a type of chemical reaction in which the oxidation states of atoms are changed. Redox reactions are characterized by the actual or formal transfer of electrons between chemical species, most often with one species (the reducing agent) undergoing oxidation (losing electrons) while another species (the oxidizing agent) undergoes reduction (gains electrons). The chemical species from which the electron is removed is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. In other words:

Oxidation is the loss of electrons or an increase in the oxidation state of an atom, an ion, or of certain atoms in a molecule.
Reduction is the gain of electrons or a decrease in the oxidation state of an atom, an ion, or of certain atoms in a molecule (a reduction in oxidation state).Many reactions in organic chemistry are redox reactions due to changes in oxidation states but without distinct electron transfer. For example, during the combustion of wood with molecular oxygen, the oxidation state of carbon atoms in the wood increases and that of oxygen atoms decreases as carbon dioxide and water are formed. The oxygen atoms undergo reduction, formally gaining electrons, while the carbon atoms undergo oxidation, losing electrons. Thus oxygen is the oxidizing agent and carbon is the reducing agent in this reaction.Although oxidation reactions are commonly associated with the formation of oxides from oxygen molecules, oxygen is not necessarily included in such reactions, as other chemical species can serve the same function.Redox reactions can occur relatively slowly, as in the formation of rust, or much more rapidly, as in the case of burning fuel. There are simple redox processes, such as the oxidation of carbon to yield carbon dioxide (CO2) or the reduction of carbon by hydrogen to yield methane (CH4), and more complex processes such as the oxidation of glucose (C6H12O6) in the human body. Analysis of bond energies and ionization energies in water allow calculation of the redox potentials.

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  1. M

    Normality of (COONa)2 - KMNO4 titration (redox reaction)

    We used 14ml of a KMNO4 solution of 0.01 Normality, to find the Normality of a (COONa)2 solution. If we took 10ml of the (COONa)2 solution, what should its Normality be? I thought about using the following equation: N1V1=N2V2 Does the stoichiometry of the redox reaction affect the equation...
  2. somasimple

    Redox products with inert electrodes?

    Hello, What are the oxidation-reduction reactions that are produced at the electrodes when they are considered inert (platinum or silver coated)? Let's take a simple example of a saline solution of KCl and apply a DC voltage between the two electrodes. Thank you in advance.
  3. il postino

    Chemistry Calculate the potential at the equivalence point

    Data ##E^{0}_{I_2/I-}= 536mV## ##E^{0}_{Cr_2O_7^{2-}/Cr^{3+}}= 1330mV## ##I_{2} + 2e- \Leftrightarrow 2I^{-}## ##Cr_2O_7^{2-} + 14H^+ + 6e^- \Leftrightarrow 2Cr^{3+} + 7H_2O## Total Reaction ##6I^{-} + Cr_2O_7^{2-} + 14H^+ \Leftrightarrow 3I_{2} + 2Cr^{3+} + 7H_2O##...
  4. I

    Chemistry Redox Reaction when a compound is both oxidized and reduced

    For the reaction between hydrogen peroxide and sodium hypochlorite, is the OCl- both reduced and oxidized? H2O2 + NaOCl -> NaCl + H2O + O2 Oxidation states: +1 -1 +1 -2 +1 +1 -1 +1 -2 0 From the oxidation...
  5. P

    Chemistry Solving for electron activity given pH and ratio of redox elements

    I've written out the half reaction 8e- + 9H+ + SO42- = HS- + 4H2O and I know the logK = 4.25 (that's the constant mentioned in the prompt) I've written out the equilibrium statement of 10^4.25 = ([x^1/8]*[H2O^1/2])/([10x^1/8]*[e-]*[(10^-8.2)^9/8] However, from there, it seems like I have two...
  6. D

    Chemistry Balancing Redox Reaction: FeS2+Na2O2→Na2FeO4+Na2SO4+Na2O"

    FeS2+Na2O2->Na2FeO4+Na2SO4+Na2O Fe2+ --->Fe+6+4e- 2S-1 --->2S+6+14e- 2O- + 2e- ---> 2O The first two have a total of 18 electrons so In order to balance the electrons i should multiply by 9 the third semireaction (2O- + 2e- ---> 2O-2)x9 now this 9 is going to multiply the left hand in...
  7. cianfa72

    Voltaic Cell behaviour as described in this video

    Hi, googling for Voltaic cell I found this video about it. At minute 2:35 to 2:54 you can see that, without any electrical conductor connected between electrodes, in the Copper half-cell the metal electrode (Cathode) gets an amount of negative charges (electrons). Basically what described there...
  8. somasimple

    RedOx Reactions & Phase Changes

    Hi, In electro-chemical cells (galvanic, concentration, etc) or more generally when some RedOx reactions occur in solutes, is there always a phase change? I mean is there always a change in the state of matter from liquid to solid or gas?
  9. S

    Optimizing Redox Reaction of FeO with H2

    Greetings, ME major here trying to brush the cobwebs off my chemistry. I can't seem to remember or recognize anything on my old chemistry textbooks regarding the optimization of a reaction. I question whether it was even taught. I'm trying to determine the most favorable conditions to ensure...
  10. alphaj

    Is this a redox reaction?

    Quick note: Sorry for dominating the homework help board, guys! But, I wanted to say thank you to everyone who replies to my excessive questions. This forum's input has become integral to me as I am in a position now where I can't go to my teacher for help because of the logistics of commuting...
  11. Wrichik Basu

    A problem in Redox Titrations (Kjeldhal's Method)

    Homework Statement :[/B] 1.08g of ##NH_4 Cl## is boiled with 62ml ##\frac {N}{2}## ##NaOH## to expel ##NH_3## completely. 44ml of ##\frac {N}{4}## ##HCl## is required to neutralise the excess alkali. Calculate the percentage of ##NH_3 ## in ##NH_4 Cl##. Answer given: 31.5% Homework Equations...
  12. Wrichik Basu

    What is the difference between valence factor and n-factor?

    What is the difference between valence factor and n-factor for oxidants and reductants? Take ##H_2O_2## as an example. What is the difference between the n-factor and valence factor for this compound? Also, how do I find the n-factor for any oxidant or reductant?
  13. A

    Questions about Redox Reactions

    Hello, Firstly, I apolagize if this should go in "HW help". It isn't homework, and the question doesn't fit the format of "HW help", but it is so elementary, so I don't know. I'll write my questions in bold. Although I think I understand what redox reactions are--a reaction in which an...
  14. D

    Balancing a redox reaction

    Hi there: I'm trying to balance a reaction in which methane is oxidized by citric acid in solution. Both methane and citric acid will be transformed into carbon dioxide. To begin, I checked that the reaction is indeed a redox reaction. C6H8O7→CO2 So, I calculated the oxidation number for...
  15. E

    Balancing disproportionation redox reaction

    Homework Statement Complete and balance the following reaction: Cl2 + OH- → Cl- + ClO- Homework EquationsThe Attempt at a Solution So, I did it like any other redox: Cl2 + 2e- → 2Cl- 2Cl2 + 4OH- → 2ClO- + 2H2O + 2e- Net reaction: 3Cl2 + 4OH- → 2Cl- + 2ClO- + 2H2O However, the answer is Cl2...
  16. R

    Balance Redox Reaction: 2PbO2 + 4H+ = 2Pb 2+ + O2 + 2H2O

    Homework Statement Balance the following oxidation-reduction reactions: PbO2 = Pb 2+ + O2 Homework Equations [/B] These are the steps I'm supposed to follow. 1. Determine the valence number (charge) for all the elements involved in the reaction. 2. Determine the number of e- given off...
  17. terryds

    Number of electrons to balance redox reaction

    Homework Statement What number of electrons to balance the equation ##I_2(s)+OH^-(aq)\rightarrow IO_3^-(aq)+H_2O(l)## The Attempt at a Solution I see that the oxidation state of I increases from 0 to +5 But, I don't see any reduction at the reaction.. So, I don't understand how to balance the...
  18. Elvis 123456789

    Is this a Redox Reaction?

    Homework Statement Determine the oxidizing agent, reducing agent, element oxidized, element reduced, # of electrons lost per atom, and # of electrons gained per atom. State if the reaction is not redox. 3FeCl2(aq) ------> 2FeCl3(aq) + Fe(s) Homework EquationsThe Attempt at a Solution...
  19. Feodalherren

    Chemistry redox reaction - gases mixing

    Homework Statement How many milliliters of Cl2 gas, measured at 28.0 °C and 750 torr, are needed to react with 18.5 mL of 0.173 M NaI if the I- is oxidized to IO3- and the Cl2 is reduced to Cl-? Homework Equations The Attempt at a Solution So the molar mass is .0030906 mol NaI...
  20. WaterMelllon3

    Redox reaction formulas or corrosion formulas?

    I was just wondering if anyone has some redox reaction formulas or corrosion formulas? Cheers Darryl
  21. G

    Need help balancing Redox Reaction

    Homework Statement Can somebody help me balance this redox reaction using either the redox number method or the half equation method? Thank You Na2S + Ag + HNO3 + Na2CrO4 ----> Ag2S + Cr(NO3)3 + NaNO3 Can you please explain your steps. Thank YouHomework Equations The Attempt at a Solution I...
  22. Mandelbroth

    Redox Reaction (An Easier Way?)

    Homework Statement From 9th edition of Raymond Chang's Chemistry (Problem 4.108): "When 2.50 g of zinc strip were placed in a AgNO3 solution, silver metal formed on the surface of the strip. After some time had passed, the strip was removed from the solution, dried, and weighed. If the mass of...
  23. B

    Balancing a Redox Reaction in Acidic Solution

    I can balance this equation using the half reaction method, but I want to learn to use the oxidation number method with this particular question to "broaden my abilities". Homework Statement ICl → Cl- + IO3 + I2 The Attempt at a Solution I: +1 → +6: lost 5e- I: +1 → 0: gained 1e- (I'm...
  24. L

    Redox reaction; standard cell potential

    Homework Statement Find the cell potential of the equations Mg^+2 + 2e- --------> mg E=-2.36v Cl2 + e- ---------> 2cl- E=+1.36v Ans: -1.00v The Attempt at a Solution The answer says that it cl2 should be flipped. And cl2 is the anode But I don't understand why. I...
  25. agnibho

    Oxidation Number to balance a redox reaction

    Homework Statement Balance Cl2+NaOH -> NaCl + NaClO3 + H2O
  26. M

    Balancing Redox Reaction by Half Reaction Method

    Homework Statement CuCl2(aq)+Al(s)→AlCl3(aq)+Cu(s) Homework Equations The Attempt at a Solution I'm just not sure what to do with a situation involving compounds. I can do simple balancing without a problem. Here is my attempt. Please, please let me know where I went wrong...
  27. H

    Balancing a redox reaction

    I am supposed to balance the following reaction: CdS + HNO3 (dil) → Cd(NO3)2 + NO + S + H2O After writing out all the oxidation numbers for each atom, I found that Cd and N are both reduced (Cd5+ → Cd 1+ and N5+ → N2+). I am wondering how to approach this problem. Is it possible to have 2...
  28. S

    Redox reaction with a twist

    Redox reaction...with a twist! In the chlor-alkali process OH–(aq) and Cl2(g) are produced by the electrolysis of a saturated solution of sodium chloride. Explain why chlorine gas rather than oxygen gas forms at the anode. The solution to the question has the word "Overpotential" and I...
  29. A

    Balancing redox reaction by half-reaction method

    Homework Statement Balance the following equation by the half-reaction method. The reaction takes place in basic solution. Fe(OH)2(s) + O2(g) --> Fe(OH)3(s)The Attempt at a Solution All the other problems like this had 2 reactants and 2 products. What's confusing me about this problem is that...
  30. A

    Chemistry Redox Reaction

    Homework Statement "State what you would infer from each of the following observations and suggest experiments you would carry out to test the validity of your inferences: When an unpleasant smelling gas was bubbled into an orange solution of a substance 'A', a solid was formed and the mixture...
  31. I

    Determination of iron purity by redox reaction

    Hi just wondering if you could help, I've stumbled across an example question where the iron purity is meant to be above 80% when 8H+ + 5Fe2+ + MnO4- → 5Fe3+ + Mn2+ + 4H2O 15cm3 is titrated and concentration of potassium permanganate used is 0.02M So far I have worked out Number...
  32. D

    Redox Reaction of Ascorbic Acid using IO3

    Homework Statement Equation 1 - IO3- (aq) + 6 H+ (aq) + 5 I- (aq) -> 3 I2 (aq) + 3 H20 The iodine formed will react with the ascorbic acid. Equation 2 - C6H8O6 + I 2 -> C6H6O6 + 2 I- (aq) + 2 H+ (aq) The goal is to determine the ascorbic acid concentration (mg/mL) in a Vitamin C solution. A...
  33. R

    Voltage for Redox Reaction

    For a reaction where the electric potential is positive, does there need to be something to provide voltage for the reaction to occur? Let's say E= 1.34V for the reaction. Do I need to connect the electrode terminals to a battery to provide 1.34V?
  34. A

    Balancing Redox Reactions: Confusion with Half-Reaction Electron Count

    Homework Statement Cr(OH)3(s) + ClO3−(aq) ® CrO42−(aq) + Cl−(aq) (basic) I am up the point where I need to balance both half-reactions for electron charge and I'm confused as to why this half reaction: ClO3− + 6H+ + 6e− ® Cl− + 3H2O, has a total of 6 electrons instead of...
  35. C

    Balancing a redox reaction involving only one apparant product

    Homework Statement Balance the following red-ox reaction that occurs in acidic solution. Homework Equations Pb(s) + PbO_{2}(s) + H_{2}SO_{4}(aq) \rightarrow PbSO_{4}(s) The Attempt at a Solution I did not see a change of oxo state from the sulfur, oxygen, or hydrogens. The lead...
  36. C

    Calculating the Equilibrium constant of a redox reaction from its half reactions

    Homework Statement Calculate the value of the equilibrium constant at 25 degrees celsius for the following reaction: 5Fe2+ + MnO4- + 8H+ ----) 5Fe3+ + Mn2+ + 4H2O Homework Equations The equation above is the product of these redox reactions: 1) MnO4- + 8H+ + 5e- ----) Mn2+ + 4H2O E=...
  37. N

    Why is bubble present, in this redox reaction?

    Homework Statement In the lab, i saw that when Mg(s) attach with Fe(s) nail in a yellow solution( probably indicator), after one day, the brown substance and bubble are formed. My net ionic equation is SOA: O2(g) +2H2O(l) +4e -->4OH- SRA: Mg(s) --> Mg2+ +2e NIE: O2(g) +2H2O(l) +2Mg(s)-->4OH-...
  38. A

    Finding ΔG and K for a given redox reaction

    Homework Statement Redox reaction: B-hydroxybutarate + 1/2O2 -> acetoacetate + H2O Half reaction 1: O2 + 4H+ + 4e- -> 2H2O (E = +0.816 V) Half reaction 2: acetoacetate + 2H+ + 2e- -> B-hydroxybutarate (E = -0.346 V) Using standard reduction potentials given, calculate ΔG calculate the...
  39. V

    Laboratory Chemisry Question - Redox Reaction

    Homework Statement 1. Explain why the following chemical reaction would not be effective to determine [Fe2+] in a given solution. Fe2+ (aq) + H2O2 (aq)-> Fe3+ (aq)+ H2O(l) | in acidic solution Homework Equations The Attempt at a Solution Hello: I am thinking that there may be a lack of...
  40. S

    Redox reaction chem problem

    H2SO4 (aq) + 2HI (aq) --> SO2 (g) + I2 (s) + 2H2O (l) Indicate the oxidizing and reducing agents. ----------------------------------------------------- I started by assigning oxidation numbers to all the atoms: H=+1 O=-2 S=+6 to +4 I=-2 to 0 I think H2SO4 is the reducing agent and...
  41. B

    Redox Reaction With Nx Nitrogen Compound

    Homework Statement Hydroxylammonium chloride reacts with Iron(III)chloride (FeCl3) in solution to produce Iron(II)Chloride, HCL, H2O, and a compound of nitrogen. It was found that 2.0 g of iron(III) chloride reacted in this way with 31 mL of 0.200 M hydroxylammonium chloride. Suggest a...
  42. C

    Redox Reaction: Fe(OH)_2+ O_2 -> Fe(OH)_3 Solution

    Homework Statement Give the net redox equations for the following reactions which occur in base solution. Fe(OH)_2+ O_2 \rightarrow Fe(OH)_3 Homework Equations noneThe Attempt at a Solution The oxidation half reaction is Fe(OH)_+OH^{-1}\rightarrow Fe(OH)_3 + e^{-}. How do we find the...
  43. K

    Redox reaction ferrocyanide

    Help me please to finish this reaction of the ferrocyanide reduction: K3Fe(CN)6 + Na2S2O3 + H2O=...? the electron transfer reaction inthis case is 2Fe(CN)3-6 + 2S2O3 = 2Fe(CN)4-6 + S4O2-6. Wondering what are the final products of the upper reaction.
  44. S

    Stoichiometry of a RedOx Reaction

    1. Oxalic acid, H2C2O4, reacts with dichromate ion, in acidic solution to produce carbon dioxide and chromium(III) ion. If exactly 50.0 mL of an oxalic acid solution is required to react completely with 25.0 mL of a 0.0100 M dichromate solution, what is the molarity of the oxalic acid...
  45. E

    Balancing a Redox Reaction

    Balancing a Redox Reaction.. urgent I have an assingment that is due tomorrow for my college chemistry class and i am stuck on the last problem. I need to balance the following redox reaction, but everytime i try it doesn't balance... H2O +I2 + OCl- ? IO3- + Cl- + H3O when i split it up...
  46. P

    Balancing a Redox Equation in Acidic Solution

    Homework Statement Balance the following redox equation (in an acidic solution): Cu + NO3- -> NO2 + Cu2 The Attempt at a Solution I got 4H+ + 2NO3- + Cu -> Cu+2+ + 2NO2 + 2H2O But my book told me the same thing, but without the H2[/sub]O: 4H+ + 2NO3- + Cu ->...
  47. D

    Redox Reaction: Adding Excess Acidified KMnO4 to Ammonium Iron(II) Sulfate

    Homework Statement Excess acidified potassium permanganate is added dropwise to an ammonium iron(II) sulfate solution. Write an overall redox equation for this process. 2. The attempt at a solution Well I am not really sure what to do. I don't know what products are being formed. What...
  48. F

    Redox reaction, changing a solution from yellow to blue

    Hello, Today, we saw an experiment where an unknown yellow solution became dark blue while it was being shaken. I have an explanation for it, but would like your opinion as well: We had a redox reaction, with the oxidation of glucose (being the reducing agent) by NaOH (being the...
  49. L

    Balanced net ionic equation for redox reaction

    Just need some idea of where to start on this one...am in my first Chemistry class and it is an intensive so we're not spending a lot of time on things. This one just has me stumped from the beginning so just some guidance on where to begin would be a huge help... Problem: Gold metal will...
  50. E

    Solving Redox Reaction Titration: Help Needed

    totally stuck! hey guys and girls, I'm having some serious problems with this redox reaction titration thing i just did! Basically i titrated a sodium thiosulphate solution with potasium iodate(v), sulphuric acid, potassium iodide and some starch. I've worked out the molarity of my sodium...