Precipitate Lab (40 Reaction Lab)

Purpose

Being able to identify a reaction has happened in solution is an important skill for a chemist, especially when many solutions are colorless liquids. Your goal for this lab is to do 40 (yes 40) reactions and make observations about each reaction. You won’t be doing all 40 reactions at once; instead you will be doing the reactions in stations.

Materials

Sodium Salts (5)

Chlorine Salts (8)

Samples of Salts

Procedure

At each station there will be 5 solutions and a grid for your reactions. Each solution will have 2-3 pipets in the beaker (note: do not mix pipets, it will ruin a solution). Take a pipet from the required solutions and place 2-3 drops of solution on the grid. Repeat the process for the other solution (keep pipet tips above the grid, do not place them in the other solution) and make observations about the possible reaction and record them in the grids in your notebook. Then repeat the process for the other reactions in the grid. You will repeat this process at each station.

You know a reaction has occurred if there is a color change or if some cloudiness appears. Think back to the Precipitate Comparison Lab and what happened in those two reactions.

Lab Report

This time you will be producing your own lab report. In your lab report you will be completing 4 tasks.

1. All of the reactions that take place are double replacement reactions. Pick 7 reactions (that occurred) and write out the complete and balanced reaction. (NaCl will always be a product along with another product. Reactants are the two solutions you reacted).

2. Write out all of the reactions that didn’t occur. Write the two reactants, the yield arrow, and then No Reaction.

3. Compare the reactions that occurred and didn’t occur. Is there any pattern? Can you come up with any trends? (e.g. all X salts react or all Y salts don’t react).

4. Using the grid provided to you, mark which reactions happened and which didn’t. Use your own coloring system to identify reactions from non-reactions (with a key).

Observations

On the demo cart there are beakers with samples of each salt as a solid. Fill in the table below with observations about the color, shape, and size of the salt.

Sodium Salts / Chlorine Salts
NaOH / CaCl2
NaI / ZnCl2
Na2CO3 / NiCl2
Na2SO4 / FeCl3
Na3PO4 / CoCl2
MgCl2
CuCl2
AlCl3