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the cell voltage of daniel cell is 1.1 v. If a voltage above 1.1v is given , what will happen, if the zinc electrode is connected to the   negative side and copper electrode on the positive side?

in the text , it is given that the flow will be reversed if we apply the a voltage higher than 1.1v if the zinc electrode is connected to the positive and the copper is connected to the negative. will the flow be reversed in the above asked conditon? is the positive , negative side important in  flow of eletrons?

 

 

The Daniell cell is basically a galvanic cell or a voltaic cell in which the energy from a spontaneous chemical reaction is converted into electrical energy. Thus in a Daniell cell, chemical energy is converted to electrical energy. The cell reaction is represented by the following chemical equation 

 Zn (s) + Cu2+ (aq) → Zn2+ (aq) + Cu (s)

Because the process of oxidation takes place at zinc electrode, therefore it acts as the anode. On the other hand, reduction occurs at copper electrode therefore it acts as the cathode. The electric potential of this cell is 1.1 V and current flows from copper electrode to zinc electrode. 

Now, if this cell is connected to an external battery then the current will continue to flow in the same direction provided the external potential is less than 1.1 V. 

 

When the external potential becomes equal to the cell potential, then the reaction stops and no current flows through the cell. 

 

However, when the external potential is greater than the cell potential, then the electron and the current will flow in opposite direction. The electrons will flow from copper to zinc and current will flow from zinc to copper. This cell now functions as an electrolytic cell, in which electrical energy is used to bring about a non-spontaneous chemical reaction. 

            

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 the +ve and -ve sides are generally decided by the electrode potentials of the two half cells. if E0 >0 then the reaction generally is a reduction half reactons and such case the electrode gets generally +ve ly charged 

but if E0 < 0 then it generally undergoes oxidation and hence the electrode act as an anode.

yes, electrons always flow from anode to cathode. the ideal potential difference for a galvanic cell is 1.1 v if in case the voltage starts increasing then more and more electrons start moving towards the cathode.. and a time will come when the cathode will act as an anode and anode as a cathode!... thts why... when we apply voltage of more than 1.1 then the zinc electrode starts acting as cathode while the coupper electrode as the anode.. and hence the flow of current and electrons are reversed!.

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