全國中小學科展

化學

熱處理對水果抗氧化的影響

本實驗是針對聖女蕃茄、櫻桃、火龍果、加州李子、奇異果與恐龍蛋等六種水果以水煮、油浴、微波、微波加油等四種方式來處理,求出水果的抗氧化活性與處理時間的關係,並且利用Arnao研究的ABTS/H2O2/HRP分析系統,以不同濃度的維生素C與延遲時間畫圖作為標準曲線來測量本實驗總抗氧化力效果。\r 由本實驗結果可以了解不論熱處理方式為何,其對六種水果之抗氧化活性初期有增加趨勢,其中以加州李子,火龍果與奇異果尤其明顯,但隨著時間增長則抗氧化活降低。為得到較佳抗氧化效果,火龍果與櫻桃宜用微波處理而奇異果與聖女蕃茄則用油浴較佳,恐龍蛋用水煮方式較適宜,加州李子則適用任何熱處理方式。 \r This research has examined the antioxidant activities of six knids of fruits under\r four diffetent ways of cooking.The fruits being tested include tomato,cherry,Hyloceeus\r polyrhizus,plum,kiwi and peach and the ways of cooking include boiled in water,fried\r in oil,microwaved and microwaved in oil.The antioxidant activites of the cooked\r fruits were evaluated by the ABTS/H2O2/HRP method developed by Arnao and they were\r compared to the antioxidant activities of vitamin C.\r \r The result showed that the antioxidant activities of six kinds of fruits under four\r different ways of cooking were initially increased with heating but they were slowly\r decreased with longer time of heating.Among those fruits tested,the antioxidant\r activities were significantly increased in plum,Hyloceeus polyrhizus,and Kiwi.To\r improve antixoidant activities of fruits by cooking,Hyloceeus polyrhizus and cherry\r is better be microwaved,kiwi and tomato is better be fried,and peach is better be\r boiled. \r

界面活性劑對硫奈米微粒形成機制的影響

硫代硫酸鈉在鹽酸中會產生自身氧化還原反應。溶液維持一段時間的澄清透明,突然快速析出硫微粒而顯得白色混濁,同時顯現廷得耳效應。溶液維持勻相的時間稱為延遲時間,其長短隨起始物濃度與溫度而異。在反應溶液中添加界面活性劑可有效增長延遲時間。以UV-Vis光譜儀分析反應溶液的吸收度變化,界面活性劑的濃度夠高時,延遲時間的倒數與添加界面活性劑濃度的倒數成簡單正比關係。此速率定律式符合界面活性劑與硫核微粒結合形成保護核的機制。陽離子性的界面活性劑如CTAB,明顯地較陰離子或中性界面活性劑有較佳的保護效果。IR及X光繞射光譜分析顯示CTAB與硫微粒有共沉澱的現象。The thiosulfate ions undergo disproportionation in hydrochloric acid to form sulfur. The reaction solutions remain clear first, followed with sudden formation of discrete particles that are observed by the appearance of Tyndall beam. The induction periods vary upon the initial concentration of the reactants and temperature. Addition of surfactant to the reaction solutions significantly prolongs the induction period, indicating the association of surfactant molecules with the nuclei of sulfur particles can hinder the aggregation of sulfur particle-nuclei. The UV-visible spectrophotometric measurements for the formation of sulfur particles in the presence of various surfactants show that the reciprocal values of induction period are proportional to the reciprocal of surfactant concentrations. Such a rate law is elucidated by an associative pre-equilibrium mechanism. The surfactant molecules appear to effectively protect the nuclei of sulfur particles from aggregation. The cationic surfactant such as CTAB demonstrates better "protection" ability than do the anionic or neutral surfactants. The IR and X-ray diffraction analysis indicate that CTAB can result in co-precipitation with sulfur, also supporting the suggested mechanism.

FeSO4 催化雙氧水製造氧氣之研究

1894年H.J.H Fenton首先發現亞鐵離子催化過氧化氫具有強氧化力,故將其稱為” Fenton reagent”。在本研究裡將對Fenton做一深入探討,探討在不同 pH值溶液、不同Fe2+濃度比下產生氧氣的效能,並且間接也印證了 HO · 自由基在 Fenton reaction 製氧過程中的重要性。 亞鐵離子在Fenton reation ,並非單純只當催化劑。當 pH =3.0、4.0、5.0時,過氧化氫與硫酸亞鐵濃度比為1:0.25、 1: 0.5 、1:1 時,當 FeSO4濃度增大時,氧氣產量依序增加。依反應機構解釋,可確定亞鐵離子為Fenton reaction 反應速率之重要因子。但,當pH 較高且硫酸亞鐵濃度為過氧化氫兩倍時,反而抑制氣氣的產量。且若當條件為 pH = 5且過氧化氫與硫酸亞鐵濃度比為 l : l 時,氧氣生成平衡體積最接近最大體積,可證實過氧化氫在短時反應最完全。由結論中幾個論點可歸納出,常實驗條件為 pH = 5且過氧化氫與硫酸亞鐵濃度比為 1: 1 時,氧氣的收集會有最好的效果。 In 1894, H. J. Fenton first found that the ferrous iron can catalyze hydrogen peroxide with the strong oxidizing ability; so we called “Fenton’s Reagent”. This discovery will make a further research to explore the efficiency of the production of oxygen that under a series of different pH values, arid different proportions of Fe2+ concentration . This experiment indirectly proves that the free radical of hydroxyl ion as a important role to produce oxygen in the Fenton reaction. In the Fenton reaction, the ferrous iron is not simply utilized as the catalyst. While the pH value is 3 4 and 5, and the proportion of hydrogen peroxide to ferrous sulfate is 1:0.25, 1:0.5, and 1:1, when the concentration of ferrous sulfate increases, the volume of the oxygen produced will increase simultaneously. According to the reaction mechanism, we affirm that the ferrous iron is a significant factor in the Fenton reaction rate. But, if the pH value is higher, and the concentration of ferrous sulfate is the double of hydrogen peroxide, the rOl1jJj1C of oxygen is refrained reversely. And as the pH value is 5, and the proportion of hydrogen peroxide to ferrous sulfate is 1: 1, the equilibrium volume of the oxygen produced will approach the maximum, which proves that hydrogen-peroxide can completely react in a short time. According to the conclusion, we conducted that as the pH value is 5, arid the proportion of hydrogen peroxide to ferrous sulfate is l:1.which is the optimum condition of the oxygen preparation.

綠色化學實驗-利用溶劑特性回收實驗後的硫酸銅

利用99%丙酮及95%酒精可以把硫酸銅晶體從實驗後的廢棄水溶液中取出來; 如同搾汁機一般,將硫酸銅結晶從水溶液中析出,其析出率可高達95.0%~90.0%。不需要外加能源,只需加入適量體積的丙酮、酒精溶劑靜置24小時不用攪拌,一顆顆漂亮的硫酸銅晶體就析出沉於底部。經過簡單的過濾及烘乾硫酸銅晶體就可以回收再利用,過濾的溶液經過簡易的蒸餾也可以回收丙酮及酒精,留在下次重複使用。如此便能解決化學實驗室硫酸銅廢液的儲存及處理。此種流程也可以用於,部分含有無機化合物的廢棄水溶液。簡易安全的操作,可回收再利用,減低衍生物的產生等,是綠色化學實驗的目標。By the use of 99% pure Acetone and 95% pure Alcohol can take the Copper Sulfate crystal out of the waste solution, as the way that juice press operates to separate the Copper Sulfate crystal from the solution. The rate or the separation can high up to 95.0%~90.0%.Without the need of extra energy, simply add proper mass of solvent like Acetone or Alcohol(refer to Result and Discussion) and place it 24 hours without stirring. Beautiful separated crystal can be recycled and ate capable to use again. By simple distillation, the filtered solution can recycle the added solvent such as Acetone or Alcohol which can also reuse next time. By doing so, the problem of storing and managing the waste solution of Copper Sulfate in laboratories of Chemistry will be solved. This procedure can also be used in parts of the waste solutions which contain inorganics. Simple and Sage operation, the capability of recycling and reusing and reducing derivatives etc., are the goals of Green Chemistry.

從導電度看乳化

界面活性劑因分子一端具極性基(polar group)而有導電性,本研究以市售之界面活性劑(PAOS洗碗精)從事其水溶液導電度探討,實驗顯示,PAOS水溶液之導電度隨溫度升高而增加,90°C之導電度約為常溫之三倍,純水之變化則極微。除溫度外,界面活性劑濃度亦影響導電度,濃度越高導電度越大,定溫(23°C)之導電度隨PAOS含量增加呈直線上升關係,PAOS含量每增2%導電度約增加1000μS,當含10%PAOS之水溶液中期導電度約增為4700μS。乳化效果對導電度亦有明顯之影響。在含PAOS 0.5~3%之水溶液中加入沙拉油,隨沙拉油加入量之增加其導電度均呈現下降現象。例如,在含有PAOS 3%之200克水溶液當中加入10克沙拉油時,其導電度約下降了15%。如果加入更多沙拉油,或者乳化攪拌過後之停滯時間過久,造成乳化平衡破壞,其導電度數據則較不規則。因此,我們可由溶液導電度之量測結果判定乳化效果,並可測定乳化攪拌之最佳條件。實驗除了以導電度探討其乳化效果外,並用顯微鏡同步觀測,以對結果做出更具說服力的解釋。將實驗數據以3D圖(立體圖)呈現以描述系統的連續變化狀態。再利用簡易的曲線回歸、斜率比較等,判定在定溫、一定攪拌條件下,清潔劑的較佳使用濃度。Surfactants have polar end groups at its molecular structure lead it with electrical conductivity in properties. This report discuss conductivity of a market purchasable surfactant named PAOS. Experiment results indicate conductivity of PAOS water solution increases with rising temperature. Triple in conductivity of this solution was found at 90°C than that of at room temperature. While the changes for pure water is very small. Except temperature influence, surfactant concentration also influence its conductivity. Generally, higher concentration gives higher electrical conductivity. At room temperature(23°C) a straight line relationship was observed between the solution concentration and the conductivity. For every increase 2% will led to increasing in conductivity for 1000 μS. When 10% PAOS in water solution is reached 4700 μS in conductivity was observed. Emulsification give obvious inference in conductivity. If cooking oil is added in 0.5~3% PAOS solution, conductivity will decrease with increasing oil added. For instance, when 10 grams of oil was added in 200 grams water solution that contain 3% PAOS, conductivity of this solution decreased for 15%. If more oil is added or setting time is too long after the solution is emulsified that destroy the emulsify balance. The conductivity of the system become irregular. In this way, it is possible to detect effect of emulsify through the measurement in its conductivity. Therefore most favorable condition in emulsification can be determined. In addition to using conductive measurement to determine effect of emulsification, microscopic technique also used trying to find even more convincible explanations. The data of different concentration experimented above can be presented on a 3D chart, we obtain several curves that can be differentially analyzed and estimated for a relatively ideal concentration, which will work more efficiently than others in the condition of the experiment.

探討如何自製便宜的耐強酸鹼實驗桌面.

This study evaluates the corrosive resistance of strong acid and base for laboratory desks including epoxy resin products, plywood, carbonate products and boards. From results,only the surface of expensive resin products can tolerate the exposure of strong acid and base. The surface of other commercial materials was destroyed with strong acid and base. The performance of laboratory-made desk surface for resistance corrosion of strong acid and base was studied. Coating with Teflon paint on the board could resistant the exposure of strong acid and base, but a drying long time was the major shortage. Some of the chitin added could improve and tolerate the scraping with knife. The results will offer to make a cheaper laboratory desk. 本研究主要是探討不同材質的實驗桌面,如環氧樹脂合成板、三合板、美耐板、一般木板等,其對強酸、鹼的抗腐蝕之極限濃度,進而研發自製經濟實用的耐強酸鹼實驗桌面。由實驗結果顯示,只有較高級昂貴的環氧樹脂合成桌面,才能夠耐高濃度的強酸、強鹼,普通的環氧樹脂桌面、三合板或美耐板其抗強酸、鹼性則不理想。若將一般木板塗以鐵氟龍漆,即可得抗強酸強鹼之桌面材質,但漆不容易乾燥,若添加適量的幾丁質於鐵氟龍漆中,則漆將極容易乾燥,可降低烘烤溫度,使木板不致因高溫烘烤而變形,此所得結果可作為製作價廉的抗強酸強鹼實驗桌面之參考。尤其本實驗所製作之板面以水果刀刮之,板面絲毫未受損,故值得我們廣為運用。

螯合劑對銅.鉛.鋅離子萃取.分離及測定之微型實驗研究

以微型實驗的方式用螯合劑:dithizone(diphenyl thiocarbazone)在四氯化碳中對金屬離子銅(Ⅱ)、鉛(Ⅱ)、鋅(Ⅱ)進行溶劑萃取與反萃取的平衡所得條件,以及由金屬離子與螯合劑結合時的莫耳數比與分離條件的探討得知,僅僅由控制溶液之pH值便可以使水溶液中的銅、鉛、鋅離子分離。於本研究中所使用之萃取光度分析法,對銅可以測至0-0.1ppm,鉛可以測至0-5.0ppm,鋅可以測至0-0.8ppm;莫耳吸光率分別為:Cu[HDz]2:4.50x104 L/moles‧cm(550nm)。Pb[HDz]2:6.85x104 L/moles‧cm(520nm)。Zn[HDz]2:9.50x104 L/moles‧cm(540nm)。其結果可做為重金屬離子廢水淨化效能之微型檢測指標。 The microscale experiment that the equilibrium of extraction and back extraction of Cu(Ⅱ)、Pb(Ⅱ)、and Zn(Ⅱ) with the extraction of chelate agent- diphenyl thiocarbazone(dithizone) in carbon tetrachloride were investigated. The conditions of extraction and back extraction of pH1/2 and the stability of these chelate compounds have the possibility to separate these Cu(Ⅱ)、Pb(Ⅱ)、and Zn(Ⅱ) mental ions in aqueous solution or in water sample mutually. The separation and determination of Cu(Ⅱ)、Pb(Ⅱ)、and Zn(Ⅱ) up to 0~1ppm(Cu), 0~5ppm(Pb), 0~0.8ppm(Zn) with dithizone in CCl4 by extraction spectrophotometry has been established. The molar absorptivity expresssed in Lmol-1cm-1 was found to be 4.50x104(550nm)for Cu[HDz]2, 6.85x104(520nm) for Pb[HDz]2, 9.50x104(540nm) for Zn[HDz]2, respectively.

仲夏夜裡的精靈-探討發光胺之化學發光反應與催化劑之作用

過去,螢光的使用只局限於釣魚、登山等無法使用電燈或火把時使用的一種較為安全的冷光。而今,我們使用這種化學發光的機會也越來越多,也再成了更多的汙染,所以我們想藉此去研討有關螢光棒之化學反應與其反應之改良。在這一篇報告當中,我們討論與研究有關Luminol發光之反應與催化劑對其反應之影響;比較在380nm~480nm範圍內不同波長所產生之光度及比較各種不同催化劑在相同波長的發光度隨反應時間的變化。我們發現在此反應之中,以k3Fe(CN)6可以產生出最大的亮度,且由實驗的結果得知Luminol的發光無法維持兩分鐘,發光時間較為短暫。映之催化效果是同時被金屬離子和根離子影響。具有明顯催化效果(最大光度超過2.5)的鹽類濃度以稀薄為佳,約10-3M。在此反應中以k3Fe(CN)6為其催化劑,可以產生一種穩定且明亮的發光,是一種較佳的催化劑在此化學發光反應之中。In the past, fluorescence was limited in being used in fishing or hiking, in which light or a torch was not available. Fluorescence is much safer because of its feature of luminescence. Today, the opportunities we use this fluorescence become more and more. The more people will use fluorescence. The more environment pollution will be caused, that is the reason we would like to study the chemical reaction of fluorescence and its solution to reduce pollution. In this paper, chemical reactions between the Luminol and different catalysis agents are studied, the comparisons between the reaction condition of the catalysis agents and the Luminol, to measure the light intensity variation in 350-500nm light wavelength range. And to measure the light intensity variation following the time of the chemical reactions between the Luminol and different catalysis. We found out that the chemical reactions between the Luminol and k3Fe(CN)6 being the catalysis agents can produce the maximum light strength. But the time of the chemical reactions is much shorter, it only can keep this chemical reactions operating in two minutes. The chemical reaction’s catalysis agent is affected by metallic ion and SO4(2-) , NO3(1-),Cl(1-), when the catalysis agent’s concentration is sparely, this luminous reaction is more obvious( the maximum light strength is over 2.5) .It can produce a fluorescence which is steady and luminous, and it is better to become the catalysis agent material of the fluorescent chemical reactions.

醣的真「本氏」─自製儀器探討還原醣與本氏液的反應過程

利用光敏電阻,設計儀器,來量測本氏液與醣類反應過程的電阻變化,將觀察到的溶液現象與R-time圖結合,提出“氧化亞銅顆粒”模型說明實驗的現象。剛開始為真溶液,電阻值低且變化少,當Cu2O的量變多,粒徑變大,電阻上升,出現廷得耳效應,顆粒大到接近光波長附近,產生繞射,電阻值呈水平,繼續變大變多後,電阻又上升,最後大顆粒產生不規則散射,使電阻值有「棉絮化」現象。溫度與濃度提升時,反應加速,R-time圖中的「水平部份」皆提早出現。延續顆粒模型觀點推導出反應速率式,將此式應用於檢測葡萄糖的濃度,溫度只需55℃,過程約需10分鐘,所用試劑量少。

Vitamin E 對回鍋油品質的影響

家庭中為了節省油量的使用,常將所剩的油品另存於容器中,以待下次使用。近年來,已有不少文獻報告指出,這種「回鍋」的使用方式,往往使得油品品質變得相當低劣。近來市面上有不少的油品,標榜添加天然維生素E,使消費者趨之若鶩,作為一種吸引消費的手段;這激發了我們極高的興趣,因為在文獻中已知道維生素E在室溫下確實可抑制油品的氧化;但添加的油品經過回鍋後,其對油品的影響卻仍不得而知。我們利用鐵鍋油炸澱粉食物,並經由反覆的油炸與冷卻,模擬更真實的回鍋情形。並添加抗氧化劑,包括維生素E和酯化的維生素E,以及回鍋次數等不同的變因進行實驗,進行油品品質的化學變化的測量。經由實驗結果顯示,經數次的回鍋烹煮,油品品質因為一連串的化學反應變得十分低劣;另外,添加酯化的維生素E的油品在某些方面的確減少了某些不良生成物的形成(如游離脂肪酸、羰基化合物等),但在某些方面如氧化程度的比較(共軛雙鍵的生成)卻與一般無添加的回鍋油無異。反倒是添加維生素E對於回鍋油品質的影響在實驗結果的每方面看來,不管是酸敗氧化或是裂解成羰基化合物都能夠有效地減少或產生抑制的作用;故添加維生素E對於回鍋油的品質的確有正面性的影響!Cooking oil is often reused in homes in order to economize on its use. In the past few years, many reports have pointed out that ”reusing” oil this way always changes the properties of oil and makes it spoiled. Also in the past few years, many oil products have appeared on market that highlight the fact that vitamin E has been added, in order to attract consumers. This attracted our interest, since we know that on the basis of several studies, vitamin E indeed has an antioxidizing effect at room temperature or below. However, it is not know what effect vitamin E has on re-cooked oil. Therefore, in this experiment we simulated the re-cooking process by frying steamed dumplings in an iron wok with soybean oil, and repeatedly cooling and re-using the oil. Variable factors were the added antioxidants(vitamin E and vitamin E acetate) and the number of re-cooking times. The chemical variation in the resulting oil was tested with regard to acid value, viscosity, carbonyl value, and the value of conjugated bonds. The results indicated that as the number of re-cooking times increased, the quality of the oil had undergone a series of chemical reactions and became spoiled. Also, the addition of vitamin E and vitamin E acetate indeed reduced the formation of certain unhealthful products such as free fatty acids, carbonyl groups, and so on. In certain respects, such as the quantity of oxidized components in the oil, there is no obvious difference between ordinary oil and oil with the vitamin E acetate additives. However, the addition of vitamin E to cooking oil, based on the results of this experiment, can effectively reduce or suppress processes causing rancidity and breakdown into carbonyl groups. Therefore, the addition of vitamin E or vitamin E acetate dose have a positive effect on re-cooked oil.