|WikiProject Chemistry||(Rated C-class, Mid-importance)|
This thing is totally messed up! When I finish my finals I'll clean it up. Kr5t 22:37, 21 May 2006 (UTC)
- If you have a chance, could you also re-write the intro? When the article was first created, the text was simply copied from the World Book Encyclopedia. Most of that text is still there. It's not a lot, but it'd be better if this were entirely written by our editors, rather than stolen from another encyclopedia. -Will Beback 20:18, 8 June 2006 (UTC)
Content from dry cell
It appears that people have confused zinc-carbon batteries, a type of dry cell battery, with dry cells. Besides zinc-carbon batteries, there are other types of dry cells, the most common being batteries. For this reason, I am posting the content from that dry cell here in case any of it can be worked into the this (zinc-carbon battery) article. I added an equals sign to allow of the sections so that it would only take up one section in this talk page. Also, I made the image into a link to the image. -- Kjkolb 07:40, 4 August 2006 (UTC)
A dry cell, also known as a Leclanché cell or a zinc-carbon battery, is a form of primary electrochemical cell that supplies electrical energy at small currents. Dry cells range in size between large flashlight batteries and tiny watch batteries but the basic construction is the same: a zinc cup lined with paper filled with an electrolyte paste with a graphite (carbon) rod in the center terminated with a metal cathode at the top.
Because it was compact and reliable, the dry cell was commonly used to power portable electronic devices such as radios and flashlights until it was replaced by alkaline cells which solve many of the dry cell's shortcomings. Everyday use of the term “battery” usually is a reference to either the dry or the alkaline cell.
Like all electrochemical cells, the dry cell gets its electrical energy from an internal chemical reaction which takes the form of two half-cell reactions. The electrolyte in the cell consists of ammonium chloride, manganese(IV) oxide, finely granulated carbon and an inert filler which is usually starch. The ammonia from the ammonium ions forms the complex ion Zn(NH3)42+ with the Zn2+ preventing buildup of Zn ions which would result in reduction of the potential of the cell.
In standard electrochemical cell notation the dry cell looks like:
- Zn(s)|ZnCl2(aq), NH4Cl(aq)|MnO(OH)(s)|MnO2(s)|graphite
With a cell potential of approximately 1.5 volts and the following half-cell reactions
At the anode (-):
- Zn(s) → Zn2+(aq) + 2 e-
- followed by Zn2+(aq) + 2 NH3(g) → [Zn(NH3)2]2+(aq)
At the cathode (+):
- MnO2(s) + H2O(l) + e- → MnO(OH)(s) + OH-(aq)
- followed by NH4+(aq) + OH-(aq) → H2O(l) +NH3(g)
The reaction is further complicated by the production of two gaseous products in the reduction of ammonium ions:
- 2 NH4+(aq) + 2 e- → 2 NH3(g) + H2(g)
These products must be absorbed within the cell if gas pressure is not to build up. Two further reactions within the paste electrolyte absorb the gas. Zinc chloride reacts with ammonia to form solid zinc ammonium chloride and manganese dioxide reacts with hydrogen to form solid dimanganese trioxide and water.
- ZnCl2(aq) + 2 NH3(g) → Zn(NH3)2Cl2(s)
- 2 MnO2(s) + H2(g) → Mn2O3(s) + H2O(l)
The cell initially produces about 1.5 volts, but this decreases as the reaction goes on because the moist paste is not completely mobile, so the electrolyte near the electrodes can be completely reacted, inhibiting further reaction, while un-reacted electrolyte is left in the body of the cell.
- They can be made very compact
- They do not require liquid water such as sulfuric acid (H2SO4), so they are more easily contained and transported and are lighter weight
- The chemicals involved are relatively safe
- Dry cells are fairly inexpensive to produce.
However, there are also several disadvantages to the dry cell:
- As a primary cell, dry cells cannot be recharged and must be discarded after their potential has dropped below a useful level.
- As mentioned earlier, the paste electrolyte is not completely mobile, so the reagents cannot be used completely.
- The zinc anode of the battery is also its outer case. As the reaction goes on, the anode is consumed and becomes thinner and thinner, until eventually the cell starts to leak. The leaked water and electrolyte make the outside of the cell sticky, and can damage the electronic device that the cell is powering.
- Shelf life is the greatest disadvantage of the dry cell, however. Even when not in use, the zinc electrode reacts with and is corroded by the electrolyte, limiting the shelf life of the cell to at most 1.5 years. Its potential decreases as well, especially in cold conditions.
Because of these shortcomings, dry cells have now been replaced by alkaline cells, which are similar to dry cells except that they use an alkaline electrolyte which the zinc electrode doesn't readily react with when energy is not being drawn from the cell.
An early dry cell was invented in 1802 by Johann Ritter.
The dry cell as we know it today was invented by Georges Leclanché in 1866. His design used a positive electrode consisting of a mixture of manganese dioxide and carbon in a porous pot. This and a zinc rod which served as the negative electrode were then immersed in an ammonium chloride solution. This became known as Leclanché's "wet" cell. Leclanché original design was prone to breakage but was improved by later engineers.
J.A. Thiebaut patented the first cell combining both the negative electrode and porous pot into a zinc cup in 1881; but Carl Gassner is credited with producing the first commercially successful dry cell in 1888 (patent 1887).
- Zinc-carbon battery (much more complicated and detailed, perhaps even clearer, explanation of chemical process inside a dry cell)
- Wet cell
- Georges Leclanché
- Galvanic cell
- Electrochemical cell
Dry cell chemisty
- Chemsoc Timeline, Dry Cell Battery 
- HyperPhysics, Batteries 
- University of Hawaii, The "Dry-Cell" Battery 
Zinc-carbon dry cell components
The main components:
- zinc- anode
- carbon rod- cathode
- paste of MnO2, NH4Cl, H2O as the electrolyte
- Porous paper- separates the paste from the Zn casing, also allows for the diffusion of ions.
- wax seal prevents the evaporation of water.
Amendment Made to Clear up Confusion of Definitions of Dry Cell and Zinc-Carbon Cell
I have now edited the dry cell page to form a link and make it a bit clearer that a zinc-carbon battery is one example of a dry cell. I hope I have made this article a little clearer to readers by doing so. Also the carbon rod is not really the cathode but is merely a collector. With reference to the above comments the manganese dioxide and carbon powder acts as the cathode as stated in the original wikipedia article zinc-carbon battery! By a former physics teacher 14 50 1st November 2006 I agree: 65 years ago dry cell typically refered to a much scaled up version of the AA cell. I believe they were otherwise identical, except they had thumb nut terminals. The inside of the zinc can had a thin film of mercury to prevent local action. A thinner film of mercury meant poorer shelf life. No mercury meant the zinc carbon battery was unacceptable for any application, but I suppose they are still made in some countries, less strict about mercury. The manganes dioxide is called a depolarizer as it removes the hydrogen bubbles which otherwise partially insulate the carbon rod from the rest of the battery. New zinc carbon batteries could deliver about 15 amps briefly to a very low resistant load. Modern alkaline batteries only about 5 amps. Typical applications require 1/2 amp or less. See alkaline batteries Ccpoodle 21:40, 13 November 2007 (UTC)
Revised Article - clear enough now?
I've revised the introduction and the chemistry reactions - hopefully that is now clear enough for interested readers. (I shifted to normal html for the equations as it is simpler and gives the same result.) Also included is a link to the Dry Cell page, which gives a simpler account. I added some details on the heavy duty (zinc chloride) cell, and more references. I removed all specific mention of hydrogen as (1) it isn't a significant side-reaction (2) some of the chemical equations were wrong.Ian 12:29, 16 March 2007 (UTC)
When were ordinary AA/AAA/C/D batteries first commonly sold? -126.96.36.199 (talk) 01:10, 18 June 2008 (UTC)
Zinc–carbon or Carbon–zinc?
[Way to not answer the question.] The question applies also to the title, which must use one or the other. The usage on Wikipedia and elsewhere may trend toward the name chosen for This Article! Before we bless the wrong name and confuse the whole world, is there a way to discover the preferred order? (Cathode first? Anode first? Metal first? Alphabetical order? Atomic-number order? First usage? Prevalent usage? Straw poll? Best argument? Loudest argument? Most persistent argument? Esthetics of sound?)
I thought it was surely a "carbon-zinc battery", but I've been brainwashed by all those Duracell® CopperTop commercials. That's why I'm looking at this talk page.
On a Google search today, "carbon-zinc battery" outnumbers "zinc-carbon battery", about 5,180,000 to about 3,940,000. That's a bit closer than I thought it would be. On Google Books, it's the opposite. "zinc-carbon battery" outnumbers "carbon-zinc battery", about 10,500 to about 9,620. It looks like the world is already confused. I'm leaving it as-is ("Zinc–carbon battery"), due to newly-acquired indifference. – A876 (talk) 22:59, 12 December 2011 (UTC)
please edit on how to dispose of this battery!
Inventor of dry cell
There may be controversion about the inventor of the dry version of this battery. This article mentions Carl Gassner as the inventor, while the article on Wilhelm Hellesen claims that he was the first inventor. Rune Kock (talk) 00:08, 5 September 2010 (UTC)
i bought one of those cheap 40 packs and kept them in a drawer. and used them as i needed. i discovered that after a certain time the used ones would leak. even if i used them for a moment, this would cause them to expand later on. the ones i had never used yet still looked new, and would expand later if i used them even for a bit. is there any explanation for this? it doesn't quite fit the explanation of the zinc corrosion in the article (The zinc container becomes thinner as the cell is used). Charlieb000 (talk) 20:18, 23 September 2011 (UTC)
It's not purity has made batteries work four times longer but right ideas. 188.8.131.52 (talk) 20:19, 9 March 2012 (UTC)Tmaker197812
The reaction for the depolariser in this article is at variance with that in the Leclanché cell. One is clearly incorrect. My belief is that this article is correct and that the other is wrong, but I can't find a suitable reference. 184.108.40.206 (talk) 15:59, 21 April 2012 (UTC)