Chemical Reactions

Chemical Reactions At least one new substance is created Bonds between atoms break, and/or the atoms bond in new combinations The new substance(s) will have different physical and chemical properties than the substances that they were made from

Chemical Equations A shortened way to show what happens during a chemical reaction. The reactants are the starting substances The products are the new substances formed from a reaction An arrow in the middle means a change has occurred (means “yields”) Reactants Products Ex/ 2 H2O 2 H2 + O2

Representing chemical reactions using diagrams…

Signs of a chemical reaction Color change Bubbling/Fizzing – gas production Odor change Energy change – gets warmer/cooler, light, sound Precipitate - production of a solid from solution

Homework Four Square Vocab Box 1. Reactant 2. Product

Aluminum and Copper Chloride solution 3 CuCl2 + 2 Al  2 AlCl3 + 3 Cu Aluminum + Copper Chloride  Aluminum Chloride + Copper

Sodium Bicarbonate and Calcium Chloride (with water and BTB) White granules + white powder  white powder + white crystal + clear liquid + colorless gas Why does it turn from blue to yellow? BTB is an INDICATOR (a chemical that changes color to indicate the presence of another chemical) It changes from blue to yellow when carbon dioxide is present

Sodium Bicarbonate and Acetic Acid NaHCO3 + CH3COOH  NaC2H3O2 + H2O + CO2 Sodium Bicarbonate + Acetic Acid  Sodium Acetate + water + carbon dioxide

Sodium Chloride and Water (H2O) NaCl + H2O  NaCl + H2O salt + water  salt water solution