Burning Steel Wool

Description:  This is an excellent phenomenon to discuss chemical reactions and the conservation of mass. Steel wool is burned leading to an increase in mass. When doing this in class show the students the burning steel wool to begin with and have them predict the change in mass. Most students believe the mass will either increase or decrease. This phenomenon can be used at the beginning of a unit on chemical reactions and students can investigate their individual models. (e.g. mass comes from fire, oxygen, carbon, etc.)

Web Resources:  Combustion of Iron Wool - CFNS Experiment 36

Slime

Description:  Everyone loves slime...especially elementary students. This phenomenon is a great introduction into chemical reactions. The properties of the reactants can be compared to the properties of the products to show that a chemical reaction has occurred. In high school the chemistry of polymers and cross-linking can be explored through slime.

Web Resource:  The Science of Slime - American Chemical Society

Elephant Toothpaste

Description:  Elephant toothpaste is a dramatic chemistry demonstration that involves the decomposition of concentrated hydrogen peroxide (H2O2) into water and oxygen. Potassium iodide is used as a catalyst to speed up the reaction. Soap is added to trap the escaping oxygen gas and food coloring is often added to the experiment. This phenomenon can be using in elementary science classes to illustrate non-reversible reactions and can be studied in more detail in middle and high school.

Web Resource:  Elephant toothpaste - Wikipedia

Limiting Reactant

Description:  In this phenomenon both magnesium metal and hydrochloric acid are limiting reactants.  I have used this in a chemistry class, framing it as "The Case of the Mixed Up Masses".  I tell them that I added varying amounts of magnesium metal but I forgot to label the flasks.  If done correctly they should get the curve seen below.  I learned about this on the NSTA Resource page.  

Web Resource:  NSTA Stoichiometry Balloon Race