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[Chem] 1996 CE Chem Paper2(MC) 有條唔明,求教

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1996 CE Chem Paper2(MC) 有條唔明,求教

Q17. A gardener bought a bag of potassium nitrate and a bag of ammonium sulphate to be used as fertilizers, He forgot to label the bags. Which of the following tests would enable him to distinguish between the two chemicals?

A. heating each chemical with dilute sulphuric acid
B. heating each chemical with sodium chloride solution
C. heating each chemical with potassium hydroxide solution
D. heating each chemical with acidified potassium dichromate solution
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答案係C,但我唔明
照計B呢,KNO3+NaCl就冇observable change,但(NH4)2SO4+NaCl應該出NH4Cl,即係有dense white fume,咁點解B係錯呢?
至於C呢,KNO3+KOH就冇observable change,jointus話KNO3+(NH4)2SO4會出NH4OH precipitate,但NH4OH咪即係NH3,係氣體黎? 我錯定jointus錯?

感謝各位!!!
   

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- it is the reaction between HCl and NH3 that gives dense white fume
- heated reaction between NH4+ and OH- gives NH3 which is a pungent, alkaline gas

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引用:
原帖由 firoazen 於 2015-12-28 06:58 PM 發表
- it is the reaction between HCl and NH3 that gives dense white fume
- heated reaction between NH4+ and OH- gives NH3 which is a pungent, alkaline gas
But the dense white fume in fact is also NH4Cl

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回覆 5# bakhan.golden 的帖子

so NH4Cl must be in dense fume?
figure out when it is and when it is not

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