1. Preparation of soap(肥皂製備)
- 將oil(油)或者fat(脂肪)同埋NaOH加熱及不時攪吓佢直至兩層layers合而為一。(oil同埋NaOH本來immiscible,但係product就solulbe in water,所以two layers become one layer)
- 然後熄火,加入brine (濃鹽水),就有d white solid(白色固體)出咗黎。(o個過程叫salting out。)
- 然後再用filtration(過濾)同埋用d distilled water洗吓d solid就得la。
(bold左嘅地方係會考嘅重要字眼o黎o架,同學仔一定要記住呀。)
2. 比較soapy(皂性)和soapless detergent(非皂性清潔)
相似:
(i) 大家都係係soft water(軟水)裡頭work嘅。
(ii) Soap 同埋 straight-chain soapless detergent(含直鍊的非皂性清潔)都係biodegradable(生物可降解)。
相異:
(i) 只有Soapless detergent係 hard water(硬水)同埋acidic solution(酸性液體)裡頭work嘅。而soap係hard water裡面就形成scum (浮渣)而o向acidic solution裡面就形成precipitate。
(ii) Branch-chain soapless detergent (含支鍊的非皂性清潔)係non-biodegradable。
同學仔睇o下下面o個table對你有冇幫助丫:
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh897oMbBiA4R5w1wnBjCy_K_yPLq7zJYpG2OoPk4r0JphmjnuVp_wZ8FHyOxy32tgQMRnVRACtR_5gzGVlgeE5_ExWXeFLP6VH5QEYhjSThKlaUPmK_OY_SD9mkipoBUNMyaBFYuEhjiE/s400/s.jpg)
仲有呀,記住讀埋how soap removes dirt on a cloth。
同之前一樣,讀熟完之後記住做下面e幾條paspaper呀,好有用o架:
1. 1995 PaperI 9a
2. 2004 Paper I 7b (包括左how soap removes dirt on a cloth嘅solution)
3. 有時間做埋1994 Paper I 5a
3 則留言:
1.咩係methylating agent?
2.如果問題比左個concentration of reactant remain 同埋time of reaction ge表你,係咪一定要試晒order 0,1,2 先可以找到個答案出黎..我次次做都徙了很多時間..
3.幾時用back titration?
4.岩岩AL果題呢,點解CaCl2唔可以用黎dry solution of C6H5COOH?係咪同Cl會replace OH 有關?
你好,我係會考生,我想請問一d野
Which of the following is often used as a primary standard?
A.hydrochloric acid
B.oxalic acid
C.calcium hydroxide
D.sodium hydroxide
Why?
hi~我係第一次黎問野架
我想問下點分一樣野係soluble in water定organic solvent?
用like dissolve like
我聽過人講polar molecule 係咩黎架呢?
eventually, 仲有咩因素取決佢既soluble 既能力同地方??
thx!!化學友
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