化學問題．．．．答得好者＋１５

A因為固體檸檬酸不能電離H+，唔可以同鎂做反應。但一有水，檸檬酸中的-COOH(有3個)

會一齊放H+，生成氫…

B本身個化應係行到既，但係，因生成左的硫酸鈣在碳酸鈣表而形成一個保護層，所以速

度減低…

b因為中和作用係放熱的，尢其涉及到強酸鹼，大量既氫氧離子及氫離子電離左出黎，有

好高腐蝕性，當你仲中和佢，放熱放得仲勁，做成化學性灼傷。

D因氨係有簡單分子結構，此情況出唔到OH-，所以test唔到佢係鹼，但係你張紅色石蕊試

紙用水將試紙浸濕就唔同講法，佢就可以放OH-，於是浸濕的紅色石蕊試紙測試變藍色，

同樣情況出現於氯化氫，不過結果相反。

E HCL本身係強酸，可以電離唒H+，咁相反乙酸唔得，於是HCL個杯有比乙酸更多的可流

動離子，導電力更好…

F抽取的溶液用具通常抽既溶液分量要好準，你有水在抽取的溶液的用具，唔單止個溶液

體積唔準，及稀釋溶液，咁過誤差就好大…但係如果你抽取的溶液抽得準，裹面冇水，

就算你個錐形瓶有幾多水都唔關事，因為有特定摩爾數既溶液抽左出黎，一定耍有番咁多

另一隻反應物同佢反應，所以蒸餾水清洗錐形瓶係可以的。

a) It is becasue the 固體檸檬酸 didn't have acid 特性, acid 特性 is mena that the H+ ions, As the 固體檸檬酸 didn't have, however, when this 溶於水時, then it will give out H+ ions, therefore, the 鎂 can react with it and 釋出氣泡
Mg + 2H+ > Mg2+ + H2

b) 大理石 is CaCO3, it is a 鹼性 , so it will react will the 稀硫酸,
i.e. CaCO3 +H2SO4 > CaSO4 + H2O +CO2
Becasue of the CaSO4 can not 溶於水, so the CaSO4 will cover the CaCO3 and reduce the surface areas, so the reaction will be slow and final stop the reaction, therefore, the 反應很快便減慢並停止

c)Because the reaction between 強鹼 and 弱酸 will give out a lot of heat, therefore, it will burn our skin, therefore, we need to 用大量清水 to 稀釋 it, to reduce the heat give out ar

d)Because when the 氨氣 react with the water, then it will give out OH- which means it is 鹼.i.e NH3 + H20 > OH- + NH4+ , Therefore, we need to 試紙浸濕, so that we can using the test 氨氣.

e) Becuse of the type of 酸, 氫氯酸 is 強酸 and 乙酸強 is 弱酸. As the導電性 is about the number of mobile ions ( free ions), As 氫氯酸 is 強酸, so it can complete ionization therefore, have more mobile ions. But 乙酸強 is 弱酸 so it can partly ionization therefore, it have less mobile ions.When they both is 1M.

f) because in 滴定 test, we need to fixed their mnumber of mod, if we using the 將要盛載的溶液 to 清洗錐形瓶, then some of the 要盛載的溶液 will keep in this 瓶, if we then put the 25.00cm3 溶液 to 錐形瓶, then it may be not 25.00cm3, may be 26.00cm3 or more, therefore, we need to use the 蒸餾水, as it will not decrease the mod of the 溶液.

A 當酸分子在水中溶解,才會有 電離 ,在液體中才有 流動電子 與鎂反應..
固體檸檬酸中沒有流動電子,所以沒有變化

B 大理石片中的CACO3 和 硫酸反應,釋出CO2氣泡。
當所有 CA 2+ 和 SO4 2- 反應、某一方為限制的反應物,
所以反應很快便減慢並停止.. 有如10個蓋 和 1 個瓶子,
最後只可做成一個完成品一樣的道理

C 如用弱酸則會有中和作用,此作用是放熱的,
會燙傷患處,用水 是因為水有高比熱容..

D 如A一樣,試紙要加水才有流動電子跟氨氣反應、顯示結果

E 弱酸(乙酸)分子只可以局部離子化,
強酸(氫氯酸)分子則可完全離子化,
比乙酸有更多流動電子去導電

F 如用溶液清洗錐形瓶,會令最後得出的溶液的濃度有變化。
在容量瓶稀釋時,加入水分不會影響溶液的濃度,因為水中的溶劑份量不變
因此用蒸餾水清洗錐形瓶,水中的溶劑份量仍然不變