Clues To Chemical ChangesWith Examples

Significant Release of Heat

• Reaction of Calcium Chloride and Water

• CaCl2 +H2O Ca(OH)2 +2HCl

Significant Absorption of Heat

• Water and Ammonium Nitrate

• NH4NO3 (s) NH4+(aq) + NO3-(aq)

Fizzing and Foamingproduction of a gas 1

• Decomposition of Hydrogen peroxide

• 2H2O2 2H2O + O2(g)

Fizzing and Foamingproduction of a gas 2

• Reaction of Vinegar and Baking soda

• NaHCO3 + HC2H3O2 → NaC2H3O2 + H2O + CO2

Production of Odor

• Castor Oil and Sodium Carbonate

• C6H6O2 + Na2CO3 C13H20O + others

Production of Light

• Phenyl Oxalate and Hydrogen Peroxide

• C14H10O4 + H2O2 C6H6O + 2 CO2

Precipitation

• Calcium Chloride and Baking Soda

• 2 NaHCO3 + CaCl2 ===> CaCO3 + CO2 + 2 NaCl + H2O•

Unexpected Change in Color