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Subject: Re: [Homebrew_PCBs] what is sulfate of zinc and acidulated water and saturated copper sulfate crystals ?

From: Rob <roomberg@...>
Date: 2017-01-17

I stumbled on this perfect answer:

What Happens in a Battery if Zinc Sulfate Is Mixed With Copper Sulfate?
by Serm Murmson

Chemical reactions can generate electrical energy from the exchange of electrons. A cell that uses the electrical current from a spontaneous chemical reaction is called a galvanic or voltaic cell. A battery is an example of such a cell. A battery is specifically constructed to ensure that its chemical reactions occur in a controlled and reliable manner.

The Nature of the Chemical Reaction
Batteries generate electrical current due to the exchange of electrons in a spontaneous reduction-oxidation, or redox, reaction. In a redox reaction, one element loses electrons: it is oxidized. Another element gains these electrons: it is reduced. The elements used in a battery are selected due to the difference in their oxidation and reduction potentials. For example, zinc loses electrons more readily than copper. A redox reaction will be spontaneous if the difference in the relevant cell potentials is positive: the system will move to release energy.
The Construction of a Battery

The cathode is the site at which reduction occurs in a battery. The anode is the site at which oxidation occurs. In many voltaic cells, the cathode and anode are made of the respective solid metals involved in the redox reaction. In order to provide ions necessary for the chemical reaction to take place, the anode and cathode are suspended in solutions containing the respective metal ions. These two solutions, called electrolytes, are connected via a membrane or barrier. In some cells this is called a salt bridge. The function of the salt bridge is to allow some ions to move while keeping others isolated in the respective electrolytic solutions. Once the anode and cathode are connected via a wire, the electrical potential difference will cause the reaction to occur. Electrons will flow over the wire.
The Zinc and Copper Battery

In a zinc-and-copper battery, the chemical reaction involves the transfer of electrons from solid zinc to copper ions. The zinc is therefore the anode; solid zinc is oxidized. The copper is the cathode; copper ions are reduced. The electrolytic solutions can be zinc sulfate and copper sulfate. When the zinc is oxidized, new zinc ions fall into the solution. When the copper is reduced, copper ions are displaced out of the solution onto the cathode. The negative sulfate ions in the copper sulfate solution can flow across the bridge to account for the creation of positive zinc ions.
The Importance of the Salt Bridge

If the salt bridge were not present, copper ions could come into contact with solid zinc. If this were to happen, both reduction and oxidation would take place at the solid zinc. Copper would build up at the anode, and the electrons would not be able to be harnessed for electrical work. Depending on the extent of the mixture of electrolytes, this could diminish the life of the battery, or even make it completely unusable for electrical work.


On 01/16/2017 02:04 PM, Jean-Paul Louis louijp@... [Homebrew_PCBs] wrote:
 

Hi Rob,

Beside having fun experimenting, what would be the use of such awfully low performance battery? the article claims high internal resistance and 0.25V capabilty.

It looks like this battery uses zinc and copper ions to work. I think that there are other ways to make a much better battery with these parameters. But picking those two metallic ions does not explain the low voltage of said battery.
According to the website at http://www.engineeringtoolbox.com/electrode-potential-d_482.html, Zinc potential is -0.76V and Copper is +0.34V, so a good battery with those elements should have a max of 1.1V, with an average probably around 1V, which is a lot better than the 0.25V advertized.

Just because you find articles on the Internet, that’s not a proof of good engineering practices.
There is a lot of garbage in the Internet, but there is also a lot of good stuff. It is just not easy to find the right ones.

As a side note, you can see on the table that lithium has a potential of -3.04V, which explains why lithium ion batteries are the hot topic.

Just a few thoughts,
Jean-Paul
N1JPL

> On Jan 16, 2017, at 2:22 AM, Rob roomberg@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
> what is sulfate of zinc and acidulated water and saturated copper sulfate crystals ?
> Do we have any chemists out there?
>
> I found an old time article how to make a battery and it specified
>
> sulfate of zinc and acidulated water and saturated copper sulfate crystals
>
> http://www.learnmorsecode.com/regen2/battery02.jpg
>
> The article said to use ZINC SULFATE
> or
> ACIDULATED water.
>
> So I got look up ZINC SULFATE on the web and is says we can buy 220mg zinc sulfate capsules...to eat.
> huh?!!??
> edible batteries?
>
> Zinc Sulfate (220mg) - 100 Capsules
> Zinc sulfate is an inorganic compound and dietary supplement. As a supplement it is used to treat zinc deficiency
>
>
> but hey...it did say "OR"
> and when I look up acidulated water it said
>
> wiki:
> Acidulated water is water that an acid has been added to it, usually lemon juice, lime juice or vinegar. Citric acid and ascorbic acid can also be used.
>
> Acidulated water can be made by combining 1.5 tablespoons vinegar or 3 tablespoons lemon juice.
>
> sooooo...... OK... this doesn't sound real toxic or dangerous to show and tell kids battery chemistry....
>
> AND THEN
> there is the saturated copper sulfate....
> which is readily available at th eharware store
> ROOT KILL copper sulfate pentahydrate 99%
> and instructions on the web say:
>
> First, you need a saturated copper sulfate solution so the crystals can form as the liquid evaporates. All you need to do to make the solution is to stir copper sulfate into very hot water until no more will dissolve. There are two ways to grow the crystals.Apr 26, 2014
> How To Grow Blue Copper Sulfate Crystals - Science Notes and Projects
> https://sciencenotes.org/how-to-grow-blue-copper-sulfate-crystals/
>
> OR
> just buy 10 pounds of crystals from a seed supply house for $32.
>
> So is this feasible or would parents be pissed if they knew their kids were near these chemicals?
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