Oxidation-Reduction Reactions

This General Chemistry lecture introduces the subject of electrochemistry by showing how to assign formal oxidation states to atoms in molecules. Reactions that involve changes in these formal oxidation states are called redox reactions, and they are prevalent in combustion. However, some systems allow us to physically separate the oxidation and reduction half-reactions and force the electrons to travel along a wire between electrodes, thereby allowing them to perform electrical work. This is the basis of the electrochemical or voltaic cell.

Category:

Education

Tags:

• chemistry
• General Chemistry
• electrochemistry
• oxidation
• reduction
• redox
• potential
• half-reaction
• anode
• cathode
• salt bridge

[drstingrae]

One question I do have in combuion (oxidation-reduction).

If you follow Gibbs free energy equation, even the combustion of Carbon compound have a point in which the favorability of spontaneity reverses the process and other compounds are formed, probabilty do to Fusion of some kind, or a release of an Alpha particle.

How do we determine this point, because plasma states are the new gig!

[chemdog8]

At extremely high temperatures, processes that maximize the entropy of a system will dominate. Compounds will break into small molecules, and then to atoms (more pieces) and then to ions (even more particles). The more particles, the higher the entropy. That's why plasma states are formed at high T. (Fusion actually goes the other way.)

[anthonychemistry]

Sir wight, About the intrinsic property of E cell. If there would be more magnitude of electrons to pass, the E cell is constant. So, its like saying electron is independent to E cell during redox.? I always commit to memory about intrinsic property of E cell just to pass the exams and of course after the exams i will be forgetting it. Is there any other intuition? please if u have some simple concepts that u can share..i will certainly appreciate..Thank u..

[chemdog8]

Hi. There are indeed effects of internal resistance, but for most chemistry courses, these are ignored. For most purposes, learning how to calculate the cell potential from the concentrations will do. Of course, if you run a cell for a while, then the concentrations will change, and then E changes. You should know how to do that using the Faraday constant and the balanced redox reaction.

[guggaman]

what about a c-c (ethyl)? ie: trichloroethylene the carbon with the two Cl is +2 and the other carbon with one Cl and the H is 0... what is the rule there? thanks.

[chemdog8]

Hi. It's exactly as you say. The two carbons have different formal oxidation states, +2 and 0. Remember, though, that oxidation states are mostly a formal concept, and the actual extent of electron transfer is usually much smaller than the formal oxidation states imply. Still, it's a useful concept for classifying the reactive properties of many atoms and molecules.

[thekillerz12345]

thanks. very good lecture

[unstoppable008]

Great lecture.

[BluMonkiSpartan]

this guy is a better lecturer than my professor and i go to one of the top universities in the us...

[kkkarenkok]

I'm doing my 1st yr. Chemistry course and from the textbook, Ecell=cathode-anode I find the sum of the half redox rXn is more simple to comprehend! Thank-you!

[TheDWiNPe]

TRADUCTION SPANISH

[Zee96969696]

i consider myself a pretty dumb guy, and I guess I'm right couse I didn't understand this video, why am I typing this? I wouldn't know

[drstingrae]

Thanks for clarifying this, I must go over fusion a little more deeply tonight before I quit!

Your insight and help is appreciated.

I really am trying to understand as mush as I can for the MCAT

[drstingrae]

Thank, love the chart at the beginning!

Good stuff!

[benjiimaster]

Thanks Chuck, very coherent lecture.