Chemistry高人請進

Physical change係表面既變化,,有顏色/氣味/溫度變化,,boiling/melting point ..etc
[[唔會生出一隻新既野]]

Chemical change係兩種野(eg. elements/compound)mix埋一齊
[[變成一種新既product產物]]..
亦都可以話係equation入面箭嘴指住果邊..

例如test for water,,
有時會用copper(II) sulphate黎試,,
equation: CuSO4 + nH2O --> CuSO4．nH2O

(nH2O個n refers to the number of water molecules)

CuSO4．nH2O呢隻叫hydrated salt水合鹽,,
[[ water加copper(II) sulphate生成hydrated salt ]],,
呢個係chemical change

water有時都可以用dry cobalt(II) chloride paper黎試,,
[[ the paper changes from blue to pink ]]
呢個就叫physical change


希望你明白=]

2007-10-16 20:53:48 補充：
任你諗幾多日常例子都係咁,,唔明就唔明架啦..你記住解釋就ok了,,最簡單咪Physical change唔會mix出一種新既野,,Chemical change相反,,會mix出一種新既野,,咁就ok啦...

其實
通常test問你咩叫physical change 同chemical change
都係叫你determine(定義)
除非叫你寫essay (但係essay會唔會問D咁簡單既呢-.-?)
我諗你問得呢條問題都係中四 or 中三 應該未洗寫住既
但係你咁問 我咁答啦

Physical change, no new substance is formed.
eg, the boiling of water is a physical change
以上既例子 只係改變左個state 都係H2O 冇new substance is formed

Chemical changem, one or more new substances are formed.
The electrolysis(電解)of water is a chemical change,
Two new substance, hydrogen gas and oxygen gas are produced in the process.

我建議你背左兩段既topic sentence 已經好夠

2007-10-16 00:23:32 補充：
仲未夠日常=.=?the boiling of water is a physical change