Part A: Instructor Demo of Two "Exciting" Reactions

1. Dehydration of sulfuric acid. This is a decomposition reaction in which sulfuric acid serves as a catalyst to promote the dehydration of sucrose. A catalyst provides a mechanism for a reaction to happen, but is not directly involved in the reaction itself. It remains unchanged throughout the course of the reaction. The decomposition products of sucrose are elemental carbon and plain old water. What do you suppose makes the carbon atoms stick together?

2. Potassium permanganate and glycerin. This reaction can be rather exciting, as a significant amount of heat is liberated. See if you can name each of the compounds in the balanced equation on page 60 of your lab manual.

Part B: Observing Some Simple Types Of Chemical Reactions.

1. Burning magnesium in air. This part is fun, but you don't want to look directly at the "flame" when this reaction is happening. The ultraviolet radiation from burning magnesium can harm your eyes. Look in Monday's notes for the formula of the product. This is the opposite of a decomposition reaction. It's called a synthesis reaction.

2. Heating magnesium carbonate. Here you'll weigh somewhere between 0.5 and 1.5 grams of MgCO₃ into a crucible. As usual, you'll record the mass to a precision of three digits beyond the decimal point. It doesn't take much to liberate CO₂ from this compound. This is a decomposition reaction and the products are CO₂ and magnesium oxide.