Qualitative analysis of ionic compounds

prelab assignment  [20 points]

1.  copy the below table.  if a precipitate forms by mixing the salts in the corresponding column and row, then place a "ppt" in the below table.

	sodium hydroxide	sodium phosphate	sodium carbonate	sodium   iodide	sodium sulfate
silver nitrate
lead II nitrate
cobalt nitrate
copper II nitrate
barium nitrate
iron II nitrate
magnesium nitrate

2.  msds information on sodium hydroxide and silver nitrate

purpose

 to observe various precipitation reactions

compare experimental observations to predictions based upon solubility rules

evaluate the reliability of the solubility rules

materials

aqueous solutions of various ionic compounds

microplate wells  [to view reaction]

methods

student design

if a precipitate does not form within a second or so upon adding the 2^nd solution, consider it to be not forming a precipitate. 

content of your lab report  [35 points; no revision for this lab report]

results & discussion   [10 points]

• using a table, compare your predictions based on the solubility rules (i.e. ppt or no ppt) versus your experimental observations (ppt, no ppt, or cloudy, i.e. opaque, transparent, or translucent, respectively).  state frequency (i.e. %) of agreement, disagreement, & ambiguous situations.
• based on the preceding table, what is the reliability of the solubility rules; elaborate, e.g. if the solubility rule is not good, then is it due to the frequency of disagreements ?  ambiguous situations ?

questions  [25 points]

• write the net ionic equation describing the reaction involving Ba(NO₃)₂ and the various sodium salts; need not balance the chemical equations.
• using concepts in this lab (i.e solubility rules), describe how to differentiate between an aqueous solution of

CuCl₂ versus Cu(NO₃)₂ (both solutions are blue) ?

AgNO₃ versus NaNO₃ (both solutions are clear) ?

include implication of the observations.

resources

lab activity source (examples):  site 1  &  site 2  [access 4 / 2009]