Galvanic Cells (Voltaic Cells)

They will bond to the metal. Now look what happened to him. the charge here is fine now we have all these advantages of zn2 but we only have some of the disadvantages of S so42 so after a while the positive charge really starts to build up in this half cell and then here as the charged ion positively. This loses its charge by gaining electrons and becomes copper with a neutral charge. Now there are many more disadvantages of s so 42 than advantages of CO2, so a negative charge starts to accumulate on this side and if this positive and negative charge accumulates too much, the cell can no longer function, it cannot continue generating electricity, so that's where the salt bridge comes into play.

Let me get rid of this cable and show you what the salt bridge looks like. Here is the salt bridge. It is an inverted U-shaped tube that in our case is filled with sodium chloride and you can see the Na+ and CL ions. Now at the ends of the salt bridge there are cotton plugs, a little cotton there and the cotton simply prevents the solution. They are poured into the half

cells

, but these ions can slowly pass through the cotton plugs and this is what happens. We said that the negative charge will start to accumulate in the half cell here and therefore positively charged na na + leaves. to start moving towards this half cell to help balance the charge, so the na+ ions are going to start moving in this direction to balance the negative charge and here we said the positive charge starts to build up, the CL minus ions are going to start to move across the salt bridge to come out through the cotton and help balance the positive charge that builds up on this side of the

voltaic

cell, so over time what we'll see is we'll see the minus cl move in this direction to balance the positive charge that is accumulating here and then we will see that the na more begin to move this way to balance the negative charge that is accumulating here.

A salt bridge helps balance these charges. to make sure they don't build up too much and that would prevent the

voltaic

cell from working. Wow, we learned a lot about

galvanic

or voltaic

cells

. Well, here is the basic structure of a voltaic cell, we have zinc. sulfate solution here copper sulfate solution here we have metallic zinc and metallic copper now when we connect all of this, the electrons start to flow from the zinc to the copper and that is because the copper that is in the solution has a strong attraction for electrons, while zinc has a weaker attraction. pull for the copper to gain as electrons move from the zinc to the copper, they are lost from the zinc so that oxidation occurs and are gained here from the copper so that reduction occurs.

Here we call it the oxidation half cell and we call it this is the reduction half cell because the oxidation is happening here the piece of zinc is the anode because the reduction is happening here the piece of copper is the cathode so finally we can write half reactions for the two processes that are happening in the different half cells Here is solid zinc that loses two electrons because it is moving to become a zinc 2+ ion that will enter the solution and then here the cu2+ ion that is in the solution gains two electrons and it becomes solid copper that is going to be joined. to this metal here and finally we can summarize all of this by writing this cell diagram or cell notation which shows everything that is happening in short form ZN solid then a line zn2 plus water this shows the oxidation part so we have these two lines represent the salt bridge or the boundary between these two cells and then we have the reduction part cu2+ line which gives us solid CU, this is how a device like a

galvanic

or voltaic cell uses a chemical reaction to create electricity.