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標題: 中三化學問題一問 [打印本頁]

作者: kennyyu 時間: 30/4/2007 10:13 PM
標題: 中三化學問題一問
我想問呢...
咩係physical change同埋chemical change丫
仲有physical properties同chemical properties又係咩呢？
急知
唔該識既幫手
同埋解釋詳細少少
唔該哂

作者: abc666 時間: 30/4/2007 10:49 PM
隨便舉例算了...

physical change:物理上有改變,化學成份沒變e.g.水變冰

chemical change:化學成份有變(可能會改變形態)e.g.acid+alkanli -> salt + water
HCl + NaOH -> NaCl + H2O

physical properties:e.g.boiling point, melting point

chemical properties:e.g.metal can react with non-metal to form salt

作者: fish 時間: 30/4/2007 10:49 PM
In simple wordings~

Physical change : there isno new substanceformed in the process
Chemical change: there is new substance(s) formed in the process

example

physical change-
dissolving sodium chloride(NaCl) in water

            water
NaCl (s)  -------------> sodium ion + chloride ion

chemical change-
completeconbustion of carbon in oxygen

C + O2  ----> CO2

phy/chem properties: (有很多很多,但CE以以下為主)

physical properties
-boiling/melting point
-malleability/dutility
-solubility
-density
-condutivity of heat/electricity

example boliling point of pure water =100degree Celsius

chemical properties
reactivity with other substances

sodium reacts with water to form hydrogen and sodium hydroxide

夠鐘返學,回來(再續!?)

算了,心情不好,不繼續了,反正都夠example

[ 本帖最後由 fish 於 30/4/2007 11:37 編輯 ]

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