Hgrh asked in 科學及數學化學 · 9 years ago

chem問題 急急急

如果有隻solution有有Zn 2+,咁用flame test去test Zn 2+,係唔係會出ZnO(熱時係黃色,凍時白)

有冇錯?flame test用係Zn 2+係唔係同flame test用係Zn一樣?比出相關

chemical equation

Update:

但係我記得flame test可以用o係solution度

我記得係用flame test wire點落d solution度,再去燒

唔係咩?

我本exercise有條話有種solution有K+,問你點test,ans就係flame test.出lilac flame

exercise錯?

3 Answers

Rating
  • Anonymous
    9 years ago
    Favorite Answer

    flame test is not applicable to solutions of salts. It can only test for presence of ions in their dry salts.

    when you put zinc salts in the flame, the flame will be bluish green in colour. however, it doesn't necessarily react to form ZnO.

    the reason why ZnO is formed when heating Zn metal is because Zn reacts with O2 in air to form the oxide:

    2Zn + O2 --> 2ZnO

    if the salt under test is ZnCl2, it just shows a bluish green flame. it will not have any reaction to form ZnO or other compounds.

    on the other hand, if the salt under test is ZnCO3, it will decompose to form ZnO.

    Therefore, whether or not ZnO is formed during the flame test of Zn salts depends on the nature of salts.

    Source(s): Victor
  • 9 years ago

    flame test is applicable to solutions of salts

  • 9 years ago

    flame test is not applicable to solutions of salts 囧...

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