每隻acid個strength都唔同
通常very dilute先當irritant
[DSE化學2019]同學準備好DSE CHEM未?
化學艾維斯
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今年整marking 個條友係唔係收唔足錢
hea 到佢
hea 到佢
巴打今年會唔會出mock卷？
一定會
出卷果個都收唔足錢啦
勁多題直抄CE pastpaper ABCD choice都一樣懶得改
勁多題直抄CE pastpaper ABCD choice都一樣懶得改
有冇得買返前幾年出既卷？
dse既題目by topic咁溫書做得七七八八 想搵啲mock試下自己咩水平
利申 dse雞
dse既題目by topic咁溫書做得七七八八 想搵啲mock試下自己咩水平
利申 dse雞
不過mc d %有驚喜
排水法主要for collect gas
petroleum入面boiling point高d果堆hydrocarbons會分離唔到
petroleum入面boiling point高d果堆hydrocarbons會分離唔到
如果隻野rtp果陣唔係gas 最多係浮上支tube入面個水面形成一層油 咁liquid state既hydrocarbons都mix返埋咪做唔到
小弟不才 唔明點解要K2MnO4
SO2 + MnO4- -> Mn2+ + SO42-
purple to colorless咪證明SO2具reducing power
另外 據我認知K2MnO4係唔可以acidified(會歧化)
所以除非你指佢成舊”酸性KMnO4溶液”寫錯曬
SO2 + MnO4- -> Mn2+ + SO42-
purple to colorless咪證明SO2具reducing power
另外 據我認知K2MnO4係唔可以acidified(會歧化)
所以除非你指佢成舊”酸性KMnO4溶液”寫錯曬
umm.....唔似CO2 wor
我理解係dehydration 再oxidize
dehydration of carbohydrate by conc H2SO4：
C12H22O11 -> 12C + 11H2O
carbon formed is then further oxidized by conc H2SO4：
C + 2H2SO4 -> CO2 + 2H2O + 2SO2
SO2 then breach fuchsin (品紅)
and excess SO2 the decolorize acidified KMnO4：
2MnO4- + 5SO2 +2H2O -> 5SO42- + 2Mn2+ + 4H+
我理解係dehydration 再oxidize
dehydration of carbohydrate by conc H2SO4：
C12H22O11 -> 12C + 11H2O
carbon formed is then further oxidized by conc H2SO4：
C + 2H2SO4 -> CO2 + 2H2O + 2SO2
SO2 then breach fuchsin (品紅)
and excess SO2 the decolorize acidified KMnO4：
2MnO4- + 5SO2 +2H2O -> 5SO42- + 2Mn2+ + 4H+
FYI
HKCEE CHEM 1998 P1 Q8(a) i & ii
You can clearly see the conc H2SO4 can act as both dehydrating agent and oxidizing agent in this process, and thus SO2 is formed.
HKCEE CHEM 1998 P1 Q8(a) i & ii
You can clearly see the conc H2SO4 can act as both dehydrating agent and oxidizing agent in this process, and thus SO2 is formed.
唔會啦 連兩支solution呢個做法都好common啫
就算只做品紅 正常for safety reason後面都會駁多支NaOH去absorb excess SO2
加上人地條題目都話左係aim for test SO2既properties
你係要話佢出錯要改做K2MO4黎test CO2好似夾硬黎左d wor
就算只做品紅 正常for safety reason後面都會駁多支NaOH去absorb excess SO2
加上人地條題目都話左係aim for test SO2既properties
你係要話佢出錯要改做K2MO4黎test CO2好似夾硬黎左d wor