標題:
CHEM''''
發問:
Which of the following can be used to distinguish between potassium chloride and iron(lll) nitrate solution ? (1) Flame test (2)Sodium carbonate solution (3)Silver nitrate solution
最佳解答:
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This question has one tricky point: For (1), please note that flame test can only test for solid sample (the platinum immersed in conc. HCl sticks some sample under testing). While for solution, it does not work. If you want to carry out flame test of solution, you must first evaporate water content of the solution first, making the solids left behind, then test the solid sample by flame test. (2): As usual, potassium carbonate is soluble in water and iron (III) carbonate is insoluble. So sodium carbonate can be used for distinguishing. (3): Silver chloride is insoluble. So silver nitrate can also be used for distinguishing.
其他解答:
all 3 can work. 1. flame test: K+ has lilac flame, Fe3+ dont have 2. Na2CO3: the answer above is WRONG. No precipitation will occur between Na2CO3 and Fe(NO3)3...This is because Fe(NO3)3 is very acidic, which react with the carbonate solution to give CO2, instead of precipitating our Fe2(CO3)3 3. Cl- forms precipitate with AgNO3, while Fe3+ do not.|||||3個都得 (1)flame test 有k+就有lilac flame fe3+當然冇啦 (2) NaCO3(aq)同KCI 冇反應 互溶 同Fe(NO3)3 就有反應 因Fe2(CO3)3 唔溶 precipitation (3)AgNO3同KCI行反應 都係precipitation AgCI唔溶 另一邊就兩樣都溶 希望幫到你啦^^" 2007-03-02 20:16:45 補充： 打得快得濟-.- 係Na2CO3
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