Observations Before Interaction Observations After Interaction How was mass conserved? Proof of a Chemical Reaction Example: Sugar + Heat The sugar is in tiny white particles in a pile. Heat is not seen but is implied by the heat source. The pile of sugar in the pot has a mass of 100 grams. There is a solid, light brown mass at the bottom of the pot. It has a mass of 100 grams. The mass of the sugar is the same in melted form as it is in solid crystal form. There was not a chemical reaction. Sugar did not change composition. It only melted. Melting point is a physical property, and this is a physical change.
Steel Wool + Oxygen (Fire)
Egg + Heat
Water + Heat
Zinc + Hydrogen Chloride
Sodium Hydroxide + Copper Sulfate