Today’s assignment is: Quiz/ test is on Tuesday!!! to actually read page 626-631 and do 1-9 on page 631 all in the textbook. Quiz/ test is on Tuesday!!! One more look at voltaic cells Ch 18 then voltaic cells

actually read page 626-631 and do 1-9 on page 631 all in the textbook.

Yesterdays assignment: Page 168 37-40 Page 170-171 24, 26-30

Electrolytic cells and the processes they are used for. Electrolytic cells use electricity to force a redox reaction that is otherwise non spontaneous. This is called electrolysis. “lysis” means to break down or separate. “Electro” lysis means to use electricity to make this happen.

Importance of Electrolysis In industrial processes, you can often separate elements in their ionic forms or covalent forms and get the neutral elements back. Separating water into hydrogen and oxygen called hydrolysis. Obtaining many substances from the ionic compounds Aluminum from bauxite Al(OH)3 Magnesium from molten MgCl2 Sodium from molten NaCl Many other reactions (note: molten ionic substances conduct electricity)

Other uses of Electrolysis reactions Electroplating-putting a coating of one metal over another. To prevent corrosion To make a metal prettier The reverse reaction in rechargeable batteries as found in an automobile for example.

No separation of the cells A comparison of voltaic cells vs. electrolytic cells. So how are they different? How does electrolysis work? Notice that the poles are reversed This is an external power source No separation of the cells

Electroplating (A closer look.) In this case there is still oxidation at the anode creating ions, but the other electrode is negative. Sooooo, Positive ions from the anode migrate (move toward) the cathode to be reduced. This time the metals are different, so we now have a process called……..

Another animation of nickel plating. Electrolysis of water animation Another animation of nickel plating. electroplating

The process can even be used to get chlorine and sodium metal from molten NaCl. How to do it

This animation shows how electrolysis works This is a hyperlink to animations of various electrolytic cells For this site under main index find the beaker and under that go to the ss or steel story there is also a powerpoint presentation of a real electrochemical cell. This is the site of norton and has a nice animation of a salt bridge electrochemical cell Also in the chapter is a good tutorial for a rechargeable nickel cadmium battery This animation is from essential chemistry and is excellent for the electrochemical cell. This site has a nice animation of metal reactivity among others. This is an animation from the above site involving a reactivity lab. This is an animation about the transfer of electrons making one neutral and the other an ion thus becoming soluble and insoluble. This animation shows how electrolysis works Electrolysis10 is a site that allows choices for electrodes and solutions

Review of worksheet Assignment: page 134 & 135; 37-41,

June 03