At the heart of work of a galvanic cell, or Daniel's element, chemical reactions for development of electric energy lie. Several galvanic cells connected among themselves make the battery. Calculation of such electrochemical cell does not make difficulties.
It is required to you
- Reference books
- Base on oxidation-reduction potentials
- Standard electrode potentials at 25o With
- Handle
- Sheet of paper
Instruction
1. To pick up chemical elements which will be used for work with the help of base on oxidation-reduction potentials. Very often in such purposes use sulfate of zinc and copper vitriol because it is very easy to get them in any gardening shop.
2. To write down a formula of a galvanic cell in a standard look. For example: By Zn | ZnSO4 | | CuSO4 | CuZdes the vertical line designates limit of the section of phases, and the double vertical line – the salt bridge.
3. To write down electrode semi-reactions, using the table of electrode potentials. Usually they are written down in the form of restoration reactions. For our example it looks as follows: Right electrode: +2Cu + 2e = CuLevyy electrode: +2Zn + 2e = Zn
4. To write down the general reaction on a galvanic cell. It represents the difference between reactions on the right and left electrodes: +2Cu + Zn = Cu + Zn2 +
5. To calculate potentials of the left and right electrodes by a formula Nernsta.
6. To calculate the electromotive force (EMF) for a galvanic cell. It, generally, is equal to potential difference of the left and right electrodes. If EMF is positive, then reaction on electrodes proceeds spontaneously. If EMF is negative, then the return reaction spontaneously proceeds. For the majority of galvanic cells of EMF there are in limits 1.1 Volta.