Demo:
Clear colorless solutions turn red, white and blue.

Application
Solutions K_sp Chemical change

Materials
HCl K₄Fe(CN)₆
AgNO₃
NH₄CHS
FeCl_3· 6 H₂O

Safety
Wear protective gloves, chemical-resistant apron and safety goggles

Preparation
Solution 1
Add 10 ml concentrated HCl to 1000 ml of DI water.
Add 8 gm FeCl_3· 6H₂O.
Solution 2 blue
0.06 gm K₄Fe(CN)₆ per litre of DI water.
Solution 3 white
1.7 gm AgNO₃ per litre of DI water.
Solution 4 red
0.07 gm NH₄CNS per litre of DI water.

Demonstration
Prepour 3 containers with 250 mls of solution 4, 3, and 2. Add a small amount of solution 1 to each to generate the colors.

Alternate, and this works better, prepour only a small amount of 4, 3, 2 in each beaker and add a large amount of 1 to each to get the colors.

Disposal
Solution may be poured down the drain and flushed with water.

Reference
California State University, Stanislaus