# How to identify ionic compounds

I have a Chemistry lab in which I must design and carry out an experiment to determine the compound in each of eight numbered vials. Each vial contains one of these ionic compounds:

• BaCl2
• CaCO3
• Ca(OH)2
• KI
• NaCl
• NaHCO3
• Na2SO4
• Pb(NO3)2

Materials:

• Distilled water
• Several microwell reaction plates
• Tooth picks (to stir)
• 8x 1mL Beral style pipets
• The contents of the lab drawer (beakers, test tubes, etc.)

In addition to the materials above, one of the following four additional reagents may be used:

• 6M H2SO4
• 6M HCl
• 6M NaOH
• phenolphthalein indicator solution

I know how to identify a couple of them. For instance, CaCO3 can be identified by its insolubility in water, but as for the rest, I'm not completely sure. I know some can be identified by how and if they react with other compounds, but I don't know exactly how to go about that.

• What are your ideas for the other compounds? Please include your attempts in your question. – jonsca Dec 17 '13 at 1:23
• I know some can be identified by how and if they react with other compounds, but I don't know exactly how to go about that. – user3960 Dec 17 '13 at 1:27

First, you can use phenolphthalein indicator solution, $\ce{Ca(OH)2}$ and $\ce{NaHCO3}$ will turn red. Then use 6M $\ce{HCl}$ and the $\ce{NaHCO3}$ bubbles.

$\ce{NaOH}$ to identify $\ce{Pb(NO3)2}$: it generates precipitations. Use $\ce{Pb(NO3)2}$ to identify $\ce{KI}$: generate golden precipitations.

$\ce{H2SO4}$ with $\ce{BaCl2}$ gives white precipitations, $\ce{Na2SO4}$ with $\ce{BaCl2}$ likewise. So the rest is $\ce{NaCl}$.

Is there any chance that you can use a Teclu or a Bunsen burner?

If so, you will need a batch of magnesia ($\ce{MgO}$) sticks too.

Most of the cations can be identified by a flame test, since they furnish a typical colour in the "blue" flame of the burners.

• Na: intense yellow
• K: lilac/violet
• Ca: brick red
• Ba: pale green
• Pb: blue/white (I had to look that up, never did it myself)