The Solubility of Ionic Compounds

The Solubility of Ionic Compounds

Purpose: The purpose of this lab was to find a set of guidelines that can help you predict the solubility of ionic compounds and to test various types of combinations of reactants to observe a precipitate. More importantly, this experiment gives us the experience on how to predict the solubility of other ionic compounds in different situations.

Hypothesis: I predict that some anions, once reacted with the cations, will be soluble and some will be insoluble.

Since the bigger molecule/atom is, the higher the level of solubility and the larger the charge, the less the solubility. I predict that Na, NH4, Ba, Ca, Cu, Mg, Ag and OH will be soluble due to their small charge and Cl, Br, CO3, PO4, SO4. CH3COO, Fe, S, and Zn will be insoluble.

Materials: 24-well spot plate

White paper

labelled dropper bottles of aqueous solutions with following cations: NH4+,

Ba2+, Ca2+, Cu2+, Fe2+, Mg2+, Ag+, Na+, Zn2+

labelled dropper bottles of aqueous solutions with following anions: CH3COO-,

Br-, CO32-, Cl-, OH-, PO43-, SO42-, S2-

Safety

Precautions: Wear goggles while conducting the experiment

Some chemicals are corrosive. Avoid tasting, smelling and exposing to skin.

If exposed to skin, rinse with a lot of cold water.

Do not contaminate the dropper bottles

Dispose of the chemicals as instructed.

Procedure: *Be sure to copy the chart provided by the instructor.

1. Obtain a 24-well spot plate along with the specified dropper bottles of solutions.

2. Add two drops of the anion and the corresponding cation in each well. Avoid cross contamination of other chemicals.

3. Examine each compound for the presence of a precipitate (cloudy appearance).

4. If a precipitate exists, place an “I” in the corresponding box of the compound. If a precipitate is not present, then place an “S” in the box.

5. Repeat these steps for all the anions and cations.

6. Dispose of the compounds in the waste beaker provided.

7. Rinse well plate thoroughly and place the chemical dropper bottles in the proper storing place.

Observations:

CH3COO- Br- CO32- Cl- OH- PO43- SO42- S2-

NH4+ S S S S S I S S

Ba2+ S S I S S I I I

Ca2+ S S I S S I S S

Cu2+ I S I S I I S I

Fe2+ I I I I I S S S

Mg2+ S S S S I S S S

Ag+ I I I I S I I S

Na+ S S S S S S S S

Zn2+ S S I S S I S S

Anions

CH3COO is mostly soluble but not soluble in Cu, Fe, and Ag

Br is mostly soluble but not soluble in Fe, and Ag

CO3 is mostly insoluble but soluble in NH4, Mg2+, and Na

Cl is mostly soluble but insoluble in Fe and Ag

OH is very soluble but insoluble in Cu, Fe, and Mg

PO4 is mostly insoluble but soluble in Fe, Mg, and Na

SO4 is mostly soluble but insoluble in Ba and Ag.

S