Chemical ReactionsI. Intro to Reactions I II III IV V
A.Signs of a ChemicalReactions Evolution of heat and lights Formation of a gass Formation of a precipitates Color change
B.Law of Conservation ofMasss mass is neither created nor destroyed in a chemical reactions total mass stays the sames atoms can only rearrange4H 4H 36 g2O 2O 4g 32 g
C. Chemical EquationsA+B → C+DREACTANTS PRODUCTS
C. Chemical Equations
D. Writing Equations 2H2(g) + O2(g) → 2H2O(g)s Identify the substances involved.s Use symbols to show: • How many? - coefficient • Of what? - chemical formula • In what state? - physical states Remember the diatomic elements.
D. Writing Equations Two atoms of aluminum react with three units of aqueous copper(II) chloride to produce three atoms of copper and two units of aqueous aluminum chloride. • How many? • Of what? • In what state?2Al(s) + 3CuCl2 (aq) → 3Cu(s) + 2AlCl3 (aq)
E. Describing Equationss Describing Coefficients: • individual atom = “atom” • covalent substance = “molecule” • ionic substance = “unit”3CO2 ⇒ 3 molecules of carbon dioxide2Mg ⇒ 2 atoms of magnesium4MgO ⇒ 4 units of magnesium oxide
E. Describing Equations Zn(s) + 2HCl(aq) → ZnCl2(aq) + • How many? H2(g) • Of what? • In what state? One atom of solid zinc reacts with two molecules of aqueous hydrochloric acid to produce one unit of aqueous zinc chloride and one molecule of hydrogen gas.