*附實驗視頻
Background Research 背景介紹
Iodine Clock Reaction, an oscillating reaction, was discovered by a chemist, Hans Heinrich Landolt, which proved Chemical Kinetics Theory. Generally, there are two or three colourless liquids mixed together. Colour changes will occur among two or three colours in the order of reactions and the sequence repeats. A period in the reaction is approximately 8 seconds. When the time of the experiment extends, the time of periods will increase. However, if you shake the bottle, the speed of reaction will increase.
碘鍾反應是一種化學的振蕩反應，在1886年被化學家Hans Heinrich Landolt發現，驗證了化學的動力學原理。一般的反應是由兩種或三種無色液體的融合，按反應順序變化出兩種或三種顏色，來回切換。它反應的周期一般為8秒，隨著實驗時間變長，周期會越來越長。當搖動瓶子時，反應速度會加快。
Materials and Apparatus 材料及儀器
97mL 29% hydrogen peroxide solution H2O2
97毫升29%過氧化氫溶液
3.9 g solid malonic acid HOOCCH2COOH
3.9克丙二酸固體
0.76 g of manganese sulphate MnSO4
0.76克硫酸錳
0.075g soluble starch
0.075克可溶性澱粉
50 ml boiling water
50毫升沸水
10.75 potassium iodate KIO3
10.75克碘酸鉀
20mL 1M sulphuric acid solution H2SO4
20毫升1M硫酸溶液
Three 250mL volumetric bottles
3個250毫升容量瓶
Distilled water
蒸餾水
Electronic balance
電子天平
Beakers
燒杯
Droppers
膠頭滴管
Measuring cylinders
量筒
Precaution 注意事項
Put on gloves, goggles, and labcoats 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 apparatus 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 andsolutions 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。
Solution A should not be left aside for too long time; otherwise hydrogen peroxide will decompose automatically.
不要將溶液A擱置太長時間，不然過氧化氫會自動分解。
When using volumetric flasks: plug the stopper into the volumetric flask to seal it, keep both hands on it (one at the bottom and the other at the top) and invert it several times to mix the solutions thoroughly.
使用容量瓶時：塞上塞子以密封容量瓶，將兩手按在瓶上（一手在頂部，一手在底部）並倒置數次以徹底將溶液混合均勻。
Procedure 步驟
Three kinds of solutions A, B, and C must be prepared for this experiment.Use a measuring cylinder to measure 97mL 29% hydrogen peroxide solution.Pour the solution into volumetric flask (a), draining with a glass rod.Add distilled water to (a) to the scale line and carefully blend them evenly to obtain 3.6mol/L hydrogen peroxide solution.Use an electronic balance to measure 3.9g solid malonic acid and 0.76g manganese sulphate.Dissolve the solids in appropriate amounts of water (add water and stir with a glass rod until they are completely dissolved), respectively.Measure 0.075g starch and dissolve it in 50mL boiling water.Pour all three solutions into another volumetric flask (b).Add distilled water to (b) to the scale line and carefully blend them evenly to obtain a mixture of 0.15 mol/L malonic acid, 0.02 mol/L manganese sulfate, and 0.03% starch solution.Use an electronic balance to measure 10.75g potassium iodate.Dissolve it in an appropriate amount of hot water (add water and stir with a glass rod untilthey are completely dissolved), and then acidify it with 20mL 1M aqueous sulfuric acid solution.Pour them into a volumetric flask (c).Add distilled water to (c) to the scale line and carefully blend them evenly to obtain a mixture of 0.2 mol/L potassium iodate and 0.08 mol/L sulfuric acid.Mix equal volumes (1: 1: 1) of solutions A, B, and C in a beaker.A mixture of 1.2 mol/L hydrogen peroxide solution, 0.05 mol/L malonic acid, 0.0067 mol/L manganese sulfate, 0.01% starch, 0.067mol/L potassium iodate, and 0.026mol/L sulfuric acid is prepared.本實驗需要三種溶液A、B和C。
溶液A：先用量筒量取97毫升29%過氧化氫溶液，用玻璃棒引流倒入a容量瓶。再倒蒸餾水稀釋至容量瓶刻度線並混合均勻，得3.6mol/L過氧化氫溶液。
溶液B：先用電子天平稱取3.9克丙二酸和0.76克硫酸錳，再分別將他們溶於適量水中（加水用玻璃棒攪拌直至完全溶解）。然後稱取0.075克澱粉溶於50mL沸水中。最後把三樣溶液都倒進b號容量瓶，倒蒸餾水稀釋至容量瓶刻度線並混合均勻，得到含0.15mol/L丙二酸、0.02mol/L硫酸錳和0.03%澱粉的混合液。
溶液C：先用電子天平稱取10.75克碘酸鉀，溶於適量熱水中（加水用玻璃棒攪拌直至完全溶解），再加入20毫升1M硫酸溶液酸化。然後倒入c容量瓶，倒蒸餾水稀釋至容量瓶刻度線並混合均勻，得到0.2mol/L碘酸鉀和0.08mol/L硫酸的混合液。
把A、B、C 三組溶液等體積（1:1:1）倒入燒杯中，此時混合溶液中有1.2mol/L 過氧化氫溶液、0.05mol/L丙二酸、0.0067mol/L硫酸錳、0.01%澱粉、0.067mol/L碘酸鉀和0.026mol/L硫酸
Observation 實驗現象
When the three colourless solutions met one another, the mixture instantly turned from colourless to yellow. This process (in the first cycle) lasted for approximately 7 seconds. Then it turned dark blue, which lasted about 6 seconds (in the first cycle). The colour changed to colourless again, which signalled the start of the next cycle (the colour change in each cycle is colourless à yellow à dark blue).
當這三種無色溶液相遇時，混合液立刻從無色變成黃色，這個過程大約持續7秒（第一周期）。然後變成深藍色，持續大約6秒（第一周期）。顏色又變為無色，意味著新周期的開始（每一周期的顏色變化為無色、黃色、深藍色）。
Principle 實驗原理
This is an oscillating reaction, which has two stable statements. Since the reaction cannot incline to one side, the two statements will appear alternately. This kind of phenomena usually happen in organisms. For instance, biological clock is one type of oscillating reaction.
During this reaction, iodide ions reacted with malonic acid to form two different stable statements. Firstly, KIO3 dissolved and reacted with H2O2 to form iodide ions, preparing for the next reaction. Iodide ions tend to form iodine molecules, for iodine is relatively unreactive. Iodide ions lose electrons to form iodine molecules. Because electrons lost must equal to electrons gained in a system, Mn2+ gained electrons to form Mn3+ and the solution became yellow.
However, when iodine meets starch, it will turn black blue, so the colour yellow only remained briefly. When all the iodide ions became iodine molecules, the malonic acid reacted with iodine molecules to form iodide ion, which was the second stable statement. At that time, the solution became colourless.
The cycle then repeated.
這是一個振蕩反應，有兩個穩定狀態，反應因無法傾向一邊，所以兩種狀態會交替出現。此類現象一般會在生物中出現，如生物鐘就是一個振蕩反應。
在這個反應中，碘離子和丙二酸在不停反應形成兩個穩定狀態。首先，當KIO3在過氧化氫中會形成碘離子，為接下來的反應做準備。碘離子傾向於變成碘單質，因為碘不活躍。在碘離子變成碘單質時，會釋放電子產生氧化反應，所以錳二價離子會得電子形成錳三價，溶液變成黃色。
但是，當碘單質遇到澱粉時，會變成深藍色，因此黃色只短暫地存在。在全部碘離子變成單質的時候，丙二酸會和碘單質反應，生成碘離子，這是第二個穩定狀態。在這個時候，溶液會變成無色。
此反應會不停地循環。
Limitations and Improvements 缺陷及改進
We did not verify the products in the reactions and determine their names according to information online, due to the lack of apparatus, materials, and knowledge. We should have decided what have been produced in person instead of believing in references only.
因設備、材料及知識限制，我們並未檢驗反應產物，所有判斷均參照網上信息，我們應該親自鑑定生成物而非僅僅相信資料。
Comments from Club Members 來自社團成員的評論
The experiment was successful. I learnt about oscillating reaction in which the colour changed between dark blue and yellow. The whole reaction lasted about 10 minutes. Later, the time interval between colour changes grew larger until the reaction finished.
實驗成功，學到了化學振蕩。顏色於深藍和黃色之間變化，整個現象持續大約十分鐘。到後期，顏色變換時間間隔越來越大，直到反應結束。
——from Tiger
——from Jason
實驗視頻
Reference 參考資料
Taylor, Gabrielle. 「Classic Chemistry:Colorize Colorless Liquids with 『Black』 Magic, AKA the Iodine Clock Reaction.」WonderHowTo, GABRIELLE TAYLOR, 12 Sept. 2012, science.wonderhowto.com/how-to/classic-chemistry-colorize-colorless-liquids-with-black-magic-aka-iodine-clock-reaction-0139128.
「碘鍾反應_百度百科.」 百度百科, baike.baidu.com/item/%E7%A2%98%E9%92%9F%E5%8F%8D%E5%BA%94/9823453.Accessed 21 Oct. 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 – Elaine Chen, Amy Zhang, and Lisa Ji（listed in no particular order 排名不分先後）