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Redox reactions

You start your car in the morning and you drive to school (or you get driven to school).  Did you know that your car uses a device to start up, and it is something that we will be studying this week in lab.  Do you know what it is? 

You guessed it - it is a battery!  Actually a car battery is really unique - when you start your car the chemicals in the battery are used in a redox reaction to generate electricity, but when your motor is idling - the electricity in your car goes to recharge the chemicals in the battery! Here is a "How Stuff Works" website about batteries.  It actually gives some ideas of how you can make your own batteries.

Redox reactions involve the transfer of electrons from one chemical substance to another.  This kind of reaction is called an electrochemical reaction.  This is because it involves electrons (electro) and chemicals in one reaction!  The hardest part of electrochemical reactions is remembering which is part of the reaction is oxidizing, and which part of the reaction is reducing.  Here is a pdf that might make this a little bit easier for you to remember. 

In part A of this experiment - you will be determining an order of reactivity.  This can be done easily by testing which chemical substances react with others, and then knowing how to place them in a proper order.  For this part of the lab - if a substance shows a reaction with a certain chemical - this means that it is "more active" than another substance that does not react with the same chemical.

Here is a good website that shows you something like what you will be doing, and you can determine your own order of reactivity before you get into lab.  Press Start on the first page, and then you can either do Activity 1, 2 or 4.  (You can also look at molecular level pictures - so you can visualize what is going on in these reactions.)

In part B of this experiment - you will be determing the electrochemical potential of some redox reactions.  Electrochemical potentials are what determines how much voltage you can get out of a chemical reaction.  Electrochemical potentials are also related to Gibbs Free Energy - and therefore are related to spontaneity of a reaction!

Posted at 04:55PM Aug 01, 2006 by CHRISTIAN, CAROLINE in General  |  Comments[5]