Sun, Aug 12, 2007 - Page 14 News List

SUNDAY SCIENCE: Shiny coins 閃亮的錢幣

By Cathernie Thomas  /  STAFF WRITER


Welcome to Sunday Science! Every Sunday during the summer, we're going to guide you through some cool experiments that you can do at home. It's a good idea for you to keep a record of what you do in a Science Journal. That way you can record what you learn, compare results and maybe use them to design new experiments! Have a look at the Science Journal box for some ideas to get you started. Remember to always ask a grown-up's permission before trying out an experiment.


Have you ever noticed how dirty some coins seem to be? This week we're going to see what kind of solution makes coins shiny again.

What you will need:

Five glasses





Dish detergent

Several dirty NT$1 coins

Barbecue tongs

A spoon (to stir the solutions with)

Old newspaper

- Place the newspaper over your working surface.

- Sort out your coins by trying to find coins which are a similar color (the dirtier the better!) This way you can judge how clean each solution makes the coins by comparing the coins.

- Place a coin in each glass.

- In the first glass, add water and detergent. Stir.

- In the second glass, add vinegar.

- In the third glass, add water and salt. Stir.

- In the fourth glass, add vingar and salt. Stir, but be very careful not to splash the mixture, it is a strong acid.

- In the fifth glass, add some cola.

- Wait for one minute then, using the tongs, remove the coins from each glass and compare. Don't forget to record your observations in your Science Journal. Remember to be careful when pouring the solutions away, and make sure that you wash the glasses thoroughly after you finish.










- 在工作檯面鋪一張舊報紙。

- 首先挑選顏色較相似的錢幣(越髒越好),這樣才能比較每種溶劑對錢幣的洗淨力。

- 在每個杯子內放入一枚錢幣。


- 在第二杯加入醋。

- 在第三杯加入水和鹽並攪拌。

- 在第四杯加入醋和鹽並攪拌,但小心別灑出來,因為混合物具強酸性。

- 在第五杯加入可樂。

- 等待一分鐘,用烤肉鉗把錢幣夾出做比較,別忘了在《科學日誌》裡記下你的觀察。記得倒掉溶劑時要小心,結束後要仔細把杯子洗乾淨。(翻譯:張愛弟)

What's the science? 科學原理

First the coins aren't just dirty. The copper in the coins reacts with air to form a layer of copper oxide. If the coins were just discolored because of dirt, the detergent would wash the dirt away and make them shiny. Because you need to remove a layer of copper oxide, you need to make a strong acid. Vinegar is an acid, but it isn't very strong. When you add salt (sodium chloride) to vinegar (acetic acid) you make a strong acid called hydrochloric acid. Cola contains phosphoric acid. Phosphoric acid is a stronger acid than acetic acid (vinegar) but weaker than hydrochoric acid.


Bonus 你知道嗎

In the US, people who have to clean up after highway accidents carry cola to clean blood off roads. Trucks carrying cola concentrate (syrup) have to carry a special warning because the concentrate is corrosive !


Vocabulary 今日單字

1. solution n.

溶劑 (rong2 ji4)

2. shiny adj.

閃亮 (shan3 liang4)

3. similar adj.

類似的 (lei4 si4 de5)

4. compare v.t/v.i

比較 (bi3 jiao4)

5. acid n.

酸性 (suan1 xin4)

6. alkali n.

鹼性 (jian3 xing4)

7. copper oxide n.

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