*附實驗視頻
Background Research 背景介紹
The elephant toothpaste experiment involves the decomposition of hydrogen peroxide, which makes the foam expand. The abundant foam produced looks like the kind of toothpaste an elephant might use to brush its tusks. So far, the largest elephant toothpaste was 200 cubic metre.
大象牙膏實驗中，過氧化氫（雙氧水）的分解使泡沫膨脹，生成的大量泡沫就像大象可能用來刷牙的牙膏。目前為止，規模最大的大象牙膏足有200立方米。
Materials and Apparatus 材料及儀器
Any amount of foaming agents (e.g. liquid soap, laundry detergent, etc.)
任意用量的發泡劑（如液體肥皂、洗衣液等）
Any volume of 30% hydrogen peroxide H2O2
任意體積的過氧化氫
Any amount of potassium iodide KI
任意用量的碘化鉀
Several conical flasks or beakers
錐形瓶或燒杯若干
Precaution 注意事項
Put on gloves, goggles, and lab coats before entering the lab.
進入實驗室之前，戴好手套和護目鏡，穿好實驗服。
Do not take off gloves, goggles, or lab coats during the experiment.
在實驗過程中不要摘下手套或護目鏡，不要脫下實驗服。
All materials used should be free of impurities and all apparatuses should be clean.
所用材料應當無雜質，儀器應當乾淨。
Do not casually change the amount of material used.
不要隨意改變材料用量。
When measuring solids, place a filter paper on the electronic balance and set zero, in order to prevent polluting the balance and to gain the accurate mass.
稱量固體時，將一張濾紙放在電子天平上並置零，以防止天平被腐蝕同時獲得精確質量（的物質）。
When measuring liquids and solutions, keep the line of sight parallel with the lowest point of the meniscus to obtain the accurate volume.
量取液體及溶液時，保持視線與凹液面最低處相平，以獲取精確的體積。
When pouring liquids and solutions into another container, ensure that glass rods are used to drain them.
傾倒液體及溶液時，確保使用玻璃棒引流。
Do not use glass rods to crush solids.
不要使用玻璃棒搗碎固體。
Hydrogen peroxide should not be left aside for too long time. Otherwise it will decompose automatically.
不要將過氧化氫擱置太長時間，不然它會自動分解。
Be careful with hydrogen peroxide, for it is a strong oxidising agent.
小心使用過氧化氫，因為它是強氧化劑。
Do not touch the foam immediately after the reaction with hands. It may cause burns.
反應結束後不要立刻用手觸碰泡沫，可能造成燒傷。
Procedure 步驟
Mix any volume of hydrogen peroxide, and any amount of potassium iodide and foaming agents together in a beaker or aconical flask. Putting foaming agents and potassium iodide into the container first is recommended. To speed up the reaction, the mixture should be stirred.
將任何體積的過氧化氫、任何用量的碘化鉀及發泡劑在一個燒杯或錐形瓶中混合，推薦先放發泡劑及碘化鉀。為了加快反應，應攪拌混合物。
Observation 實驗現象
The foam expanded rapidly. Water vapour was seen rising into the air from the foam.
泡沫快速膨脹，水蒸氣升騰至空中。
Principle 實驗原理
Hydrogen peroxide underwent decomposition (H2O2 à H2O+ O2). The steam coming out and the hot foam suggested that it was an exothermic reaction (the gas was not oxygen because oxygen is invisible). The foam expanded since oxygen produced pushed it up. Potassium iodide acted as a catalyst which only influence the rate of the reaction (speeded it up here) without affecting its yield (hydrogen peroxide can decompose automatically without any help).
過氧化氫分解，升騰的水蒸氣和熱泡沫表明這是一個放熱反應（這個氣體不是氧氣是因為氧氣不可見），泡沫膨脹是因為生成的氧氣將它推起。碘化鉀是催化劑，只影響反應速率（在這裡是加速）而不影響產量（過氧化氫可以自行分解）。
Limitations and Improvements 缺陷及改進
We did not delve into this experiment, which means we should have studied variables to obtain the best result. Different amounts of catalyst, volumes of hydrogen peroxide, and amounts of foaming agent would have affected the rate of the reaction.
我們沒有深入研究這個實驗，也就是說，我們應該研究變量以得到最好的效果。不同用量的催化劑、過氧化氫及發泡劑應該會影響反應速率。
Comments from Club Members 來自社團成員的評論
This experiment can be considered successful, but we did not figure out the most suitable amount of materials, so the result was not ideal.
這個實驗做得還算成功，不過我們並沒有找到最合適的材料用量，所以效果並不理想。
——from Jolynn
Obviously, what we came up with is very interesting【Grin】. We are thinking about making the toothpaste on a larger scale. That will be spectacular.
自己想出來的實驗當然很有趣，想著可不可以做個超大版，感覺會很壯觀。
——from Susan and Paco
實驗視頻
References 參考
「大象牙膏_百度百科.」百度百科,https://baike.baidu.com/item/%E5%A4%A7%E8%B1%A1%E7%89%99%E8%86%8F/3839848. Accessed15 Nov. 2020.
註：本報告僅限於自我查看，由學生撰寫，所有中英文轉換皆為意譯（而非直譯）；因此內容不一定精確，請在查看時慎重決定。
作者：Crazy Experiment Club - Amy Zhang