Chemical changes are represented with chemical equations, a shorthand method of describing a chemical reaction. Chemical equations do two things: 1. Identify the reactants and products. 2. Tell the relative numbers of each substance.
Anatomy of a Chemical Reaction FORWARD DELTA: ARROW: Shows that Means heat is Reactants produces or supplied to Products yields, etc. the reaction CH4 (g) + 2O2 (g) CO2 (g) + 2H2O (g)SUBSCRIPT: PLUS SIGN: COEFFICIENT:Tells how many ITALICIZED Used to Tells how manyatoms there are ABBREVIATION: separate of each reactantof an element Tells what each or each product physical state that reactant or there is reactant or each product S product is in Y (g): reactant or (l): reactant or product in M product in gaseous liquid state B : state (aq): designates an aqueous O (s): reactant or solution; substance L product in solid state dissolved in water S
Anatomy of a Chemical Reaction cont’ Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 UPWARD ARROW: Shows gas is produced in the reaction2KI (aq) + Pb(NO3)2 (aq) 2K(NO3)(aq) + PbI2 DOWNWARD ARROW: Shows a precipitate is produced
Anatomy of a Chemical Reaction ….. Catalyst: Speeds up reaction without participating in rxn I- 2H2O2 (aq) O2 + 2H20 (l) IN WORDS… Hydrogen Peroxide reacts to form Oxygen gas and water 2SO2(g) + O2 (g) 2SO3(g) DOUBLE ARROW: Reaction is reversible IN WORDS…Gaseous Sulfur Dioxide reacts with Oxygen gas to form gaseousSulfur Trioxide
Writing Equations… ∆ MnO2 2. KClO3(s) O2(g) + KCl(s) 3. HgS(s) + O2(g) Hg(l) + SO2(g)Describe in words: NaHCO3(s) + HCl (aq) NaCl (aq) + H2O(l) + CO2(g)When solid sodium bicarbonate reacts with a solution ofhydrogen chloride (hydrocholoric acid), it forms aqeuoussodium chloride, water, and carbon dioxide gas.
Writing Equations….. **Write the Following Equations…. 1. Solid Sulfur burns in oxygen gas to form sulfur dioxide gas S(s) + O2 (g) SO2(g)2. Oxygen gas can be made by heating potassium chlorate in the presence of a manganese (IV) oxide catalyst. Potassium chloride is left as a solid residue3. When solid mercury (II) sulfide is heated with oxygen, liquid mercury metal and gaseous sulfur dioxide are produced.
Try: When solid ammoniumnitrite is heated, it producesnitrogen gas and water vapor. NH4NO2(s) → N2(g) + H2O(g) Δ NH4NO2(s) → N2(g) + 2H2O(g)