Chemistry

Daniell Stacks


Observe the following oxeduction chemical reaction:

This reaction can be accomplished very easily by placing a piece of metallic zinc (Zn °) in a beaker with an aqueous copper sulfate (CuSO) solution.4), which is a translucent blue liquid.

After some time, about 20 minutes, it can be observed that the piece of metal turned reddish. The part that has turned red is the copper (Cu °) that has deposited on the zinc plate. And at the bottom of the glass there is the formation of zinc sulfate (ZnSO4) according to the reaction above.

This experiment, which can be done even at home, demonstrates oxirreduction reactions.

The experience made by the English meteorologist and chemist John Frederic Daniell, in 1836, constitutes a pile formed from oxirreduction reactions.
Battery - These are chemical reactions that produce electric current.

Daniell set up a system with two interconnected electrodes. An electrode consisted of a zinc plate immersed in a beaker with a zinc ion solution, in this case zinc sulfate.

The other electrode consisted of a copper plate immersed in a beaker with a copper ion solution, in this case copper sulfate.

He called the zinc electrode a negatively charged anode.
He called the copper electrode a positively charged cathode.

Source: educar.sc.usp.br/licenciatura/2006/Daniel_Pilha/Daniell_pilha.html

Anode or negative pole It is the electrode where the electrons come out. The reaction of oxidation.

Cathode or positive pole It is the electrode where the electrons go. The reaction of reduction.

Over time, the zinc plate electrons go into the solution, increasing the solution concentration and corroding the zinc plate.

On the other electrode, the opposite occurs. The electrons in the copper sulfate solution deposit on the copper plate, decreasing the solution concentration and increasing the metal plate mass.

Source: cabarequimico.blogspot.com/2008/11/eletroqumica-abrange-all-process.html

Here's how to mount the reactions that occur in Daniell Stack:

1 °) mount anode reaction
2 °) mount cathode reaction
3 °) add the reactions, forming the overall reaction of the cell.

Note: Similar terms cancel each other out. In the case, in the above reaction, the 2es.

Daniell placed a salt bridge consisting of a U-glass tube containing aqueous KCl solution.

Its function is to allow the migration of ions from one solution to the other so that the number of positive and negative ions in the solution of each electrode remains in equilibrium.

Following is a summary table of the Daniell Stack.

ELECTRODE

REACTION

POLE

BLADE

SOLUTION

ANODE

OXIDATION

NEGATIVE POLO (-)

CORRÓI

CONCENTRA

CATHODE

REDUCTION

POSITIVE POLO (+)

INCREASES

DILUI