A voltaic cell is based on the two standard half-reactions Cd2+1aq2 + 2 e- ¡ Cd1s2 Sn2+1aq2 + 2 e- ¡ Sn1s2 Use data in Appendix E to determine (a) which half-reaction occurs at the cathode and which occurs at the anode
A voltaic cell is based on the two standard half-reactions Cd2+1aq2 + 2 e- ¡ Cd1s2 Sn2+1aq2 + 2 e- ¡ Sn1s2 Use data in Appendix E to determine (a) which half-reaction occurs at the cathode and which occurs at the anode
A half reaction can be oxidation or reduction reaction and both the reaction takes place simultaneously in a redox or oxidation-reduction reaction. If the chemical species undergoes chemical reaction by losing of electron, then the species get oxidized and the reaction is called oxidation half reaction. On the other hand, if the chemical species undergoes chemical reaction by gaining electron, then the species get reduced and the reaction is reduction half reaction. When a species undergoes oxidation, then its oxidation number increases and if it undergoes reduction, then its oxidation number decreases.
The given standard half reactions are along with its reduction potential in appendix E are,
Cd2+(aq) + 2 e- ---> Cd (s) Eored = - 0.4 V
Sn2+(aq) + 2 e- ----> Sn (s) Eored = - 0.14 V
Now, as the reduction potential of Cd is more negative than Sn, hence Cd has more reducing power than Sn, so Cd acts as a reducing agent and reduces Sn at cathode and itself get oxidized at anode.
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