化學對人類的主要貢獻是可以利用化學反應，獲得人類所需要的新物質。人類可以利用化學反應的規律獲得需要的物質或能量。
The major contribution that chemistry has on human society is that new substances could be attained through chemical reactions. Also, human beings can control and make use of the chemical reactions.
那麼，
如何讓培養目標在化學課堂中體現出來？
如何在課堂上培養學生探索化學反應的興趣呢？
如何讓學生進一步形成有關物質結構的基本概念?
How can we integrate the 10 attributes in the Chemistry class? How to cultivate students』 interest in inquiring into chemical reactions?How to enable students to further form the basic concept of the structures of materials?
初步認識物質的結構與性質的關係，能從物質結構決定性質的視角解釋一些化學現象。
so that they could have a preliminary understanding about the relationship between the structure and function of a material, which could be applied to explain some chemical phenomena.
王梅靜 Nancy Wang
東北大學應用化學專業本科，東北大學有機化學專業研究生，加拿大阿爾伯塔大學化學專業研究生，從事IG，A-level化學教學3年。
現為蘇城外國語學校國際高中化學教師。
Bachelor’s Degree in Applied Chemistry, and Master’s Degree in Organic Chemistry, Northeastern University; Master’s Degree in Chemistry, University of Alberta, Canada. Having been pursuing the career of teaching IG, A Level Chemistry for three years.
肥皂是我們生活中常用的必需品，但是大家知道它是由我們平常食用的橄欖油或者其他油脂制出的嗎？
Soap is one of our daily necessities, yet how many of us know that it is made from the olive oil that we use for cooking or other fats?
So, Nancy shall take the foundation program students to make an inquiry.
製作手工肥皂的原料通常是：氫氧化鈉、油和水。
NaOH, oil and water are the raw materials for making handmade soap.
氫氧化鈉（NaOH，俗名火鹼、燒鹼、苛性鈉。）是製造肥皂的重要原料之一。
NaOH is one of the most important raw materials for making soap.
常溫下是一種白色晶體，具有強腐蝕性。易溶於水，其水溶液呈強鹼性。氫氧化鈉溶液加油，比例適當下會反應混合成為固體肥皂。這一反應也是利用了水解的原理，而這催化下的酯水解稱為皂化反應。
NaOH is also called Lye. With some oil, reaction will happen to its solution in proper proportion. This reaction also utilizes the principle of hydrolysis, which is also known as saponification. Saponification: the reaction of making soap between fats or oils and lye.
討論階段 How to make the soap with oil
怎樣才能製作肥皂呢？首先我們要配製一個Lye 溶液。向一定量的油裡面，加入Lye 溶液，並不停的攪拌。同學們在製作肥皂的過程中，可以加入自己喜歡的精油，顏料和香味。完全成粘稠狀之後，倒入模具中，等待成型。
How to make soap? First, we need to prepare a Lye solution. Add the Lye solution into a certain amount of oil, and keep stirring. During the process of making soap, students can also add some essential oil, pigment and fragrance they like into it. Pour into the mold when it becomes sticky completely, and wait for molding.
Picture : 1) Lye solution with water；2) measure the amount of oil；3) Add the Lye solution to oil and stir；4) Add essential oils, pigments and fragrance, pour to the mold.
那麼問題來了，
我們需要加入多少的NaOH，
才可以做出一塊好的肥皂呢？
However, how much NaOH do we need to make a qualified soap?
同學們經過討論得出來，如果鹼性含量過高，它的刺激性會讓我們的皮膚再度受損。雖然肥皂是短時間接觸皮膚就用清水衝洗掉，但它造成的傷害絕不容忽視。如果鹼的量加入過少，那麼皂化反應會不完全，肥皂中的油脂過剩。
After discussion, students came into the conclusion that too much base will irritate and damage our skin. Even though the skin is exposed to the soap for a very short period of time, the damage it has cannot be ignored. Saponification shall not complete if there is too little base with excessive oil in the soap.
同學們很快地總結出了規律。原來是皂化是很難完全的反應，會讓一些 NaOH 殘留在肥皂裡，導致肥皂的pH值升高。對皮膚不好。所以反應的時候，我們都會加少一些NaOH, 讓它成為少量試劑，Limiting reagent.
The students immediately summarized the law. It turned out that saponification is hard to achieve complete reaction, so that some NaOH will remain in the soap, causing the PH value to rise. This would be harmful to our skin, so we often make the NaOH a limiting reagent.
為了保證實驗的成功，我們用包含了組合的油脂以及NaOH 混合的皂基，來做實驗。
To ensure the success of this experiment, we experimented with the soap base containing a combination of oils and NaOH.
在實驗過程中，有幾個小問題給大家思考：
During the process of experiment, few questions were also raised for everyone to think about:
什麼是SAP Value, 它的值是越大越好嗎？
What is SAP Value? Is it the larger, the better?
肥皂的洗滌原理是什麼？
What is the principle of soap washing?
不同的油脂，製造出來的肥皂的品質有什麼不同？
How the quality of soap differs by using different oils?
首先，我們用電子天平稱量150g皂基，用酒精燈加石棉網的裝置，不停地攪拌，把皂基融化。加入15mL的牛奶，攪拌。測量pH值。
First, we used the electrical balance to weigh 150g soap base, and used the alcohol burner and asbestos net to heat the soap base. During this process, we should keep stirring until the soap base melted. Add 15ml milk into it and stirred. Measure the PH value.
加入自己喜歡的精油和顏料，趁熱倒入模具中，等待一小時成型。
Add the essentials oils and pigments we like, pour it into the mold and wait for an hour.
皂化價是指要皂化1kg的油脂所需的氫氧化鈉的克數。皂化價的高低表示了脂肪酸分子量的大小，即碳原子個數的多少。
SAP value: saponification values, equates to the number of milligrams of KOH (potassium hydroxide) it takes to convert or "saponify" a fat into soap. It is the average molecular weight of the amount of fatty acids present.
那麼皂化價是越高越好嗎？
Is the SAP value the higher, the better?
同學們討論的結果是，肥皂有一個親油端（hydrophobic tail）和親水端(hydrophilic head)。如果親油端過長，則親油性好，親水性不足。如果親油端過短，則親油性不足。所以皂化價不是越高越好。
After discussion, students drew the conclusion that soap has a hydrophobic tail and a hydrophilic head. If the hydrophobic tail is too long, it is more hydrophobic. If the hydrophobic tail is too short, it is less hydrophobic. Therefore, higher SAP value doesn’t mean the better quality of soap.
在課堂的最後，老師給學生們布置了書寫實驗報告的任務。讓他們將此次實驗的探索、總結、理解、討論寫成一個實驗報告。
By the end of this class, the teacher assigned the students to write a lab report, where they could officially record their inquiry, summary, comprehension, and discussion in this experiment.
這堂課從生活出發，講解抽象的製作肥皂的理論知識。給學生提出了很多問題，引導學生去分析，回答問題。在教學中，我們以學生參與為主，注重激發學生的學習思考能力，讓學生主動參與到我們的化學學習中來。
Taking the real-life events as the starting point, this class gave a vivid explanation about the theoretical knowledge about how to make a soap. Many questions raised, students were guided by the teacher to analyse and solve these questions on their own. During the teaching process, we were student-centred, focusing on stimulating students』 thinking skills. Therefore, students could actively engage in the Chemistry learning.
通過學生動手去做肥皂，激發了學生的學習興趣，使學生將生活中的應用與化學的理論知識結合起來，既有趣味，又有深刻的理解。
Students』 learning interests were inspired by making the soap by themselves. Also, students could apply the theoretical knowledge learned in Chemistry class into our daily practice, making the intriguing and profound learning truly happen.
中文撰稿：王梅靜
英文翻譯：沈紫煙
攝影：宣傳辦 國際高中
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