Galvanic cell question

[euphaire]

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Hello,

I just started learning this topic today after reviewing electronegavity. The kaplan book says a typical galvanic cell consists of a Zn half cell and a Cu half cell, where Cu is the cathode and Zn is the anode. The reactions are:

Zn(s)->Zn2+(aq)+2e (anode)
Cu(2+)(aq)+2e->Cu(s) (cathode)

I got confused here. According to the Periodic Table, isn't Zn the MORE electronegative one? Since electronegativity increases from left to right. That would mean Zn should be the cathode (accept electrons) and Cu should be the anode, which is not the case. Clearly, the "default" arrangement of Zn anode and Cu cathode is more favorable since the galvanic cell is spontaneous. But why is this the case? Would it still be spontaneous if the Cu becomes the anode instead? How do you determine the spontaneity of this particular reaction?

Thanks in advance to anyone who can help me out 🙂

Cherry

 

[loveoforganic]

http://www.tutor-homework.com/Chemistry_Help/electronegativity_table/electronegativity.html

Those trends really only hold true for main group elements.

 

[saiwahhh]

Hello,

I just started learning this topic today after reviewing electronegavity. The kaplan book says a typical galvanic cell consists of a Zn half cell and a Cu half cell, where Cu is the cathode and Zn is the anode. The reactions are:

Zn(s)->Zn2+(aq)+2e (anode)
Cu(2+)(aq)+2e->Cu(s) (cathode)

I got confused here. According to the Periodic Table, isn't Zn the MORE electronegative one? Since electronegativity increases from left to right. That would mean Zn should be the cathode (accept electrons) and Cu should be the anode, which is not the case. Clearly, the "default" arrangement of Zn anode and Cu cathode is more favorable since the galvanic cell is spontaneous. But why is this the case? Would it still be spontaneous if the Cu becomes the anode instead? How do you determine the spontaneity of this particular reaction?

Thanks in advance to anyone who can help me out 🙂

Cherry

The Zn/Cu example is a Daniell cell. Not all Galvanic Cell's will contain the Zn/Cu. I think what you should take away from this concept is basically the idea that you need salt bridge, and what will be the anode/cathode, where the electrons will mode towards, where oxidation/reduction will occur and why.

Just my two cents, good luck!