Name 3. separate test tubes? Explain in words how you could tell, and give the n
ID: 548167 • Letter: N
Question
Name 3. separate test tubes? Explain in words how you could tell, and give the net-ionic equation for any reaction that occurs in the test. a. Pb(NO, and Ca(NO), solutions Reagent b. PbCl, and AgCl solids Reagent: c. HNO, and HCl solutions Reagent: A student has an unknown solution that can contain any combination of Group I cations. A white precipitate (PI) forms when excess 6 M HCl is added to the unknown. After discarding the supernate (S1), hot water is added to the precipitate (P1) and the mixture boiled for 5 minutes. After removing the mix- ture from the hot water bath, it is left at room temperature for 10 minutes before centrifuging and removing the supernate (S2) from the precipitate (P2). S2 gives no precipitate when 1 M K,CrO, is added. When 15 M NH, is added to P2a black precipitate forms. Complete the following table. For each cation, put a check mark to indicate whether the description allows you to say that the cation is defimitely preent, definitely absent, or posibly present or absent 4. Possibly Present or Absent Ion Present Absent Ag Pb2*Explanation / Answer
3.
(a)
Add HCl solution, if a white precipitate forms, it is Pb(NO3)2, otherwise it is Ca(NO3)2
Pb(NO3)2 (aq.) + 2 HCl (aq.) ---------> PbCl2 (white precipitate) + 2 HNO3 (aq.)
Ca(NO3)2 (aq.) + HCl (aq.) -------------> No Reaction
(b)
Add ammonia solution, if precipitate dissolves, it is AgCl otherwise it is PbCl2.
AgCl (s) + 2 NH3 (aq.) ------------> [Ag(NH3)2]Cl (aq.)
PbCl2 (s) + NH3 (aq.) ------------> No Reaction
(c)
Add AgNO3 solution if precipitate forms, it is HCl otherwise HNO3.
HCl (aq.) + AgNO3 (aq.) ----------> AgCl (white precipitate) + HNO3 (aq.)
HNO3 (aq.) + AgNO3 (aq.) -----------> NO Reaction
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