coins – Danupon Drake

September 26, 2017February 6, 2019

Turning a Coin to Silver and Gold (Simple Redox Reaction)

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This simple experiment will make you understand the redox reaction. This is one of my favorite experiments so I decided to make a post about it.

Things you’ll need: a copper coin (a penny, basically), zinc powder, sodium hydroxide (more than 50%), alcohol lamp, forceps, and a beaker.

Pour Sodium Hydroxide into a beaker and pour some zinc dust in it, enough to cover the coin.
Put the coin the beaker and wait for a couple hours, I’ll be using my country’s copper coin.
Take the coin out with forceps and wash it with water, now you have a silver coin.
If you want to continue, do the following steps: Make sure the coin is dry. Heat it up with an alcohol lamp until it’s yellow.
Enjoy.

An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of electrons between two chemicals. A redox reaction is any chemical reaction in which the oxidation number of a molecule, ion, or atom changes by losing or gaining an electron. For example, like this experiment, the zinc transferred its ions to the copper; that’s how the coin turned silver, and that’s why this is a redox reaction. What about turning it to gold? The color of silver and copper are just mixing together when heated and that makes the gold color.

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August 2, 2017December 16, 2022

I Figured out why the Coins look Different

Remember the coin experiment that I performed lately?

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When I washed the coins, they looked different.

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But why?

I finally figured out the answer.

Copper metal is oxidized by the Ag¹⁺ to Cu²⁺ and the Ag¹⁺ions are reduced by the copper metal to silver metal.

But do you remember what the coins are made of?

Penny: The alloy remained 95 percent copper and 5 percent zinc until 1982, when the composition was changed to 97.5 percent zinc and 2.5 percent copper (copper-plated zinc) until now. Cents of both compositions appeared in that year.

50 Satang (Thai baht): The core is 99% iron and cladding is 99% Copper.

10 Yen (Japanese Yen): 95% copper, 3–4% zinc, and 1–2% tin.

The Penny turned yellow-orange because the zinc was mixed with copper.

The Thai coin turned darker because of the iron.

The Japanese coin turned yellow because of the zinc and tin. Tin is light yellow and zinc is gray.

I hope you enjoyed that experiment, if you did, comment down below ↓

Sources:

www.chem.indiana.edu/faculty…/5-5%20Silver%20Tree%20Redox%20Reaction.doc

July 31, 2017December 16, 2022

The Silver Coin

What about this experiment? Remember the silver tree? That was a great experiment. Go over there and check it out (here: https://danupondrake.wordpress.com/2017/06/25/the-silver-tree/). The silver nitrate will stick to the copper coil and make crystals. But instead of copper coils, why don’t we try copper coins? It will be fun to try! Let’s get started then!

Let’s some coins from different countries.

Penny (19 mm diameter): The alloy remained 95 percent copper and 5 percent zinc until 1982, when the composition was changed to 97.5 percent zinc and 2.5 percent copper (copper-plated zinc) until now. Cents of both compositions appeared in that year.