[Chem] 以下反應既observations!!!急求

[匿名]

2011-12-04 6:51 am

-Find the observations of mixing the following few aqueous solutions(eg: 1.XXXcolour precipitates formed /2.Colourless bubble released)(If no, then say no observable changes):
1. HNO3(aq) + NaCl(aq)
2. HNO3(aq) + Na2CO3(aq)
3. HNO3(aq) + Pb(NO3)2 (aq)
4. NaCl(aq) + Na2CO3 (aq)
5. NaCl (aq) + Pb(NO3)2 (aq)
6. Na2CO3(aq) + Pb(NO3)2 (aq)

- PS: Provide full chemical equations for the reactions

*Further question: Briefly explain how to distinguish those 4 aqueous solutions by the observation and the chemical equations if those 4 aqueous solutions are not known before the reactions.

回答 (1)

賣女孩的火柴

2011-12-04 11:38 am

✔ 最佳答案

1.
No observable change

2.
Colourless gas bubbles are given off.
2HNO3(aq) + Na2CO3(aq) → 2NaNO3(aq) + H2O(l)+ CO2(g)
or: 2H^+(aq) + CO3^2-(aq) → H2O(l) + CO2(g)

3.
No observable change

4.
No observable change

5.
A white precipitate is formed.
2NaCl(aq) + Pb(NO3)2(aq) → PbCl2(s) +2NaNO3(aq)
or: Pb^2+(aq) + 2Cl^-(aq) → PbCl2(s)

6.
A white precipitate is formed.
Na2CO3(aq) + Pb(NO3)2 (aq) → PbCO3(s) +2NaNO3(aq)
or: Pb^2+(aq) + CO3^2-(aq) → PbCO3(s)

2011-12-05 16:09:23 補充：
Answers to further question :

NaCl: It gives a white precipitate when mixing with only one other solution.

Pb(NO3)2 : It gives white precipitates with two other solutions.

2011-12-05 16:09:54 補充：
Na2CO3: It gives a white precipitate with only one other solution, and gives colorless bubbles with only one other solution.

HNO3: It gives colourless bubbles with one other solution, but gives no precipitate with other solutions.

參考: 賣女孩的火柴, 賣女孩的火柴

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