F.3 (chem) -- 10 *2=20分ga!!

(a) 無新substance is formed所以係 physical change

(b) 無新substance is formed所以係 physical change
(有crystal生成, 但crystal 仍然係 copper (II) sulphate)
等於飽和鹽水生成鹽結晶(crystal), 此crystal 仍為鹽
(如果說formation of crystal 係 chemical change)<----講個人真係識chem?

(c) 生成 lead and carbon dioxide (new substances), 所以係 chemical change

(d) 生成 hydrogen gas and oxygen gas (new substances)所以係 chemical change

a) physical change
*因為mixing 的process中並沒有新物質formed
只是純粹把兩者混合一起

b) chemical change
*因為在crystallization的process中產生了new substance
而該new substance 就是crystal

c) chemical change
*同樣地，因為在decarbonization的process中產生了new substance
而該new substance 就是lead

d) chemical change
*因為在electrolysis(電解)的process中產生了new substance
水(H2O)被break down(分解)為hytrogen(H)和oxygen(O)
而水本身的特徵也失去了
因此是chemical change

2007-09-24 21:52:46 補充：
我想樓上的第二位朋友在d)那題答錯了只有在electrolysis of sea water才會出現chlorine gas的還有，electrolysis of sea water只會出現chlorine gas，hydrogen和sodium hydroxide solution並沒有oxygen。

2007-09-24 22:05:50 補充：
補充::也許我不能說electrolysis of sea water中沒有oxygen的出現但是sodium hydroxide是sodium，hydrogen和oxygen的compound因此oxygen並不是以element的身份出現而是以oxide的形式出現

(a) Physical change
Becuase NO new substance is formed

(b) Physics change
Because NO new substance is formed (ALL methods of separation are physical changes)

(c) Chemical change
Because NEW substances (Lead & Carbon dioxide) are formed.

(d) Chemical change
Because NEW substances (Hydrogen gas, oxygen, chlorine gas, ... ) are formed.

a) physical change
b) chemical change
c) chemical change
d) physical change<<<呢個唔肯定