4. Redox reactions Describe chemical reactions in which electrons are exchangedchemical reactions Oxidation is the loss of electronselectrons Reduction is the gain of electrons “Leo goes Ger” lose electrons oxidation, gain electrons reduction Oxidizers (electron acceptor) Substances that have the ability to oxidize other substances are said to be oxidative or oxidizing and are known as oxidizing agents, oxidants, or oxidizers. Put another way, the oxidant (oxidizing agent) removes electrons from another substance i.e. it oxidizes other substances, and is thus itself reduced. And, because it "accepts" electrons, it is also called an electron acceptor.oxidizing agentselectron acceptor Reducers (electron donor) Substances that have the ability to reduce other substances are said to be reductive or reducing and are known as reducing agents, reductants, or reducers. The reductant (reducing agent) transfers electrons to another substance i.e. it reduces others, and is thus itself oxidized. And, because it "donates" electrons, it is also called an electron donor.reducing agentselectron donor A good example is the reaction between hydrogen and fluorine in which hydrogen is being oxidized and fluorine is being reduced: ie, F gains electrons from Hhydrogenfluorine H 2 + F 2 → 2 HF

6. In the example below F gains an electron from Mg. F is being reduced and Mg is being oxidized

7. REDOX REACTION – Metabolic Example For example, redox reactions result in the transfer of electrons from glucose to oxygen. Glucose is oxidized to CO 2 and oxygen is reduced to water. C 6 H 12 O 6(aq) + 6O 2(g)  6CO 2(g) + 6H 2 O (l) + E (Heat & ATP) Aerobic cellular respiration – The overall process is accomplished through about 20 reactions in which the product of one reaction is the reactant of the next. – Hydrocarbons contain a number of C-H bonds which oxygen oxidizes in two ways. – In aerobic cellular respiration 12 hydrogen atoms break from glucose and attach to 6 of the O 2 molecules to become 6 H 2 O molecules. Oxidation because each hydrogen atom carries an electron from carbon in glucose and brings it to oxygen. – Remaining oxygen atoms bond to carbon from glucose forming 6 CO 2 molecules. – Also oxidation because oxygen is more electronegative than carbon and as such, pulls electrons towards itself and away from carbon when bonded. – Essentially equal to losing electrons (for carbon) which gives off energy. Yields 2870kJ of energy per mole of glucose (~ 180g).