會考的化學問題 (20分)

2007-12-30 2:03 am

如果依家有一個樽, 樽入面裝左兩種液體，係paraffin oil (石蠟油) and water with few drops of phenolphthalein (一種測試鹼性的試劑). 由於個density 問題，油浮左係水上面。如我我依家放一粒sodium(鈉)入去個樽到，粒sodium 會沉左去邊同會唔會有咩reactions?

P.S. 兩種液體and sodium係放落同一個樽到的
Sodium 個 density係 0.97 g cm-3
paraffin oil 個density係 0.82g cm-3
water 加左phenolphthalein 的density 就唔知係咩

Pls help me

回答 (1)

tetrachloromethane

2007-12-30 6:04 am

✔ 最佳答案

呢條係past paper黎架喎
sodium is denser than paraffin oil so it sinks
but it is also less dense than water
it reacts with water but no air is present so no fire is observed
hydrogen is released and brings the metal up the paraffin oil
when the hydrogen is discharged, it sinks again
this contiuous to happen until all the metal is reacted
the phenolphthalein solution turns pink because hydroxide ion is formed

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