Cells/batteries (1 Viewer)

[gadbil]

hey guys i have an assignment and i have to gather and present information on the structure and chemistry of a dry cell or lead acid cell … and evaluate it in comparison to…one of the following:
-fuel cell
button cell
vanadium redox cell
lithium cell
liquid junction photovoltaic device

In terms of: – chemistry, – cost and practicality, – impact on society, – environmental impact

What should i choose? what ones would have alot of information on the net about them.

 

[tennille]

You can just google the each of the cells and check for yourself. The button cell has information at http://en.wikipedia.org/wiki/Watch_battery, the lithium cell at http://en.wikipedia.org/wiki/Lithium_battery. Just look them up using google or wikipedia and whatever has the most information you can do your assignment on.

 

[Forbidden.]

From my workbook:

Brief description:
A common dry-cell is the Zinc-Carbon battery, also known as the Leclanché cell.

Diagram of cell in words:

The positive electrode consists of a (grahite) carbon rod and the negative electrode consists of a zinc outer casting. Manganese oxide covers the (graphite) carbon rod. A moist paste of ammonium chloride fills between the manganese oxide and zinc casing.

Other notes:

The battery has a cell emf of about 1.5V

The chemical equation for the (overall) reaction is

Zn(s) + 2MnO₂(s) + 2H⁺(aq) --> Zn²⁺(aq) + Mn₂O₃(s) + H₂O(l)

The carbon rod acts as a conductor, however, hydrogen ions present can cover up the rod and increase internal resistance.
(Resistance is the reduction of electron flow BTW)

Carbon-Zinc cells are highly versatile due to lower-costs and their variety of shapes and sizes
[(Like AAA, AA, C, D ... just like the supermarket ones(Not part of my book)] and are used in alarms, clocks, calculators, flashlights, remote controls, radios and many portable handheld appliances. (Practical applications in blue)

From Excel:

The Daniell cell was very difficult to use because of the electrolytes but, in 1890, Leclanché developed a 'dry cell' which we now use with very little modification in torches, pocket radios, toys and some calculators. It delivers about 1.5V

Half-Cell reactions:

(i) Oxidation reaction at the anode (-ve)

Zn(s) --> Zn²⁺(aq) + 2e^-

(ii) Cathode reaction (+ve)

2MnO₂(s) + 2H⁺(aq) + 2e^- --> Mn₂O₃(s) + H₂O(l)

NH₄⁺ ions provide H⁺ ions needed for cathode process.

NH₄⁺(aq) <--> NH₃(aq) + H⁺(aq)

Overall,

Zn(s) + 2H⁺(aq) + 2MnO₂(s) --> Zn²⁺(aq) + Mn₂O₃(s) + H₂O(l)

This cell cannot be recharged

NB:

-ve means negative and +ve means positive

 

[chocolate_lover]

Uhhhh, u just did her assignment for her...

 

[gadbil]

lol, thanks alot f3nr15 it really helped me