Chemical Reactions

Objectives 1) Write and balance equations 1) Write and balance equations 2) Identifying the types of reactions 2) Identifying the types of reactions

Reactants and Products Gallium + Sulfuric acid → Gallium Sulfate + Hydrogen Reactants- left side of the arrow Reactants- left side of the arrow -starting materials -starting materials Products-right side of the arrow Products-right side of the arrow -the substance made, produced -the substance made, produced The number of atoms on the reactant side must equal the number of atoms on the product side. The number of atoms on the reactant side must equal the number of atoms on the product side.

Balancing Rules: 1) Write the correct chemical formula for the reactants and the products. 1) Write the correct chemical formula for the reactants and the products. 2) Adjust the coefficients (the numbers that appear in front of the formulas) only and evenly. 2) Adjust the coefficients (the numbers that appear in front of the formulas) only and evenly. 3) Never change the subscripts (the small numbers in a formula) 3) Never change the subscripts (the small numbers in a formula) 4) When counting atoms, multiply the coefficients by the subscript for each element. 4) When counting atoms, multiply the coefficients by the subscript for each element. 5) There are seven elements, that when left alone, exist as diatomic molecules. 5) There are seven elements, that when left alone, exist as diatomic molecules. Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2 Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2

Balancing Example Ga + H 2 SO 4 → Ga 2 (SO 4 ) 3 + H 2 Ga + H 2 SO 4 → Ga 2 (SO 4 ) 3 + H 2 Balanced: Balanced: 2Ga + 3H 2 SO 4 → Ga 2 (SO 4 ) 3 + 3H 2 2Ga + 3H 2 SO 4 → Ga 2 (SO 4 ) 3 + 3H 2

Identifying Reactions The five types of reactions: The five types of reactions: -Synthesis or Combination -Synthesis or Combination -Single Replacement -Single Replacement -Double Replacement -Double Replacement -Combustion -Combustion -Decomposition (6 types) -Decomposition (6 types)

Synthesis element + element → compound element + element → compound Occurs when two or more elements are combined to form a new substance Occurs when two or more elements are combined to form a new substance Also called Combination Also called Combination

Synthesis or Combination Example: Example: 2 Na + Cl 2 → 2NaCl 2 Na + Cl 2 → 2NaCl Jayhawk says: Here’s an example of synthesis: + = Rivalry

Single Replacement Occurs when one element displaces another in a compound. Occurs when one element displaces another in a compound. A + BC → B + AC A + BC → B + AC element + compound → element + compound

Single Replacement Example: Na + LiCl → NaCl + Li Na + LiCl → NaCl + Li Listen up,class, it’s time for an example.

Double Replacement Occurs when the positive and negative ions of the two reactants are interchanged Occurs when the positive and negative ions of the two reactants are interchanged AB + CD → AD + CB AB + CD → AD + CB compound + compound→compound +compound compound + compound→compound +compound Never put two metals together Never put two metals together

Double Replacement Example: 2NaCl + Li 2 O → Na 2 O + 2LiCl 2NaCl + Li 2 O → Na 2 O + 2LiCl Did you know? Double replacement is also referred to as metathesis.

Combustion Hydrocarbon + O 2 → H 2 O + CO 2 Hydrocarbon + O 2 → H 2 O + CO 2

Combustion Example: C 4 H 8 + O 2 →H 2 O + CO 2

Decomposition Occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied. A compound may decompose to form simpler compounds and/or elements. Occurs when energy in the form of heat, light, electricity, or mechanical shock is supplied. A compound may decompose to form simpler compounds and/or elements. compound → 2 or more substances compound → 2 or more substances →

Decomposition There are 6 different types of decomposition There are 6 different types of decomposition Did you know? You might also know decomposition by analysis.

Electrical Decomposition AB → A + B AB → A + B 2NaCl → 2Na + Cl 2 2NaCl → 2Na + Cl 2

Decomposition: Oxy-Acid Oxy-Acid → Water + Nonmetal Oxide Oxy-Acid → Water + Nonmetal Oxide H 2 SO 4 → H 2 O + SO 3 H 2 SO 4 → H 2 O + SO 3Examples: HNO 3 HNO 3 H 3 PO 4 H 3 PO 4 HClO 2 HClO 2

Decomposition: Metallic Hydroxide Metallic Hydroxide → Metal Oxide + Water Metallic Hydroxide → Metal Oxide + Water 2LiOH → Li 2 O + H 2 O 2LiOH → Li 2 O + H 2 O Fe(OH) 2 → FeO + H 2 O Fe(OH) 2 → FeO + H 2 O

Decomposition: Metallic Carbonate Metallic Carbonate → Metal Oxide +Carbon Dioxide MgCO 3 → MgO + CO 2 MgCO 3 → MgO + CO 2 Fe 2 (CO 3 ) 2 → Fe 2 O 3 + 3CO 2 Fe 2 (CO 3 ) 2 → Fe 2 O 3 + 3CO 2

Decomposition: Metallic Chlorate Metallic Chlorate → Metal Chloride + Oxygen Metallic Chlorate → Metal Chloride + Oxygen 2LiClO 2 → 2LiCl + 3O 2 2LiClO 2 → 2LiCl + 3O 2 Ca(ClO 3 ) 2 → CaCl 2 + 3O 2 Ca(ClO 3 ) 2 → CaCl 2 + 3O 2

Decomposition: Metallic Oxide Metallic Oxide → Metal + Oxygen Metallic Oxide → Metal + Oxygen 2Li 2 O → 4Li + O 2 2Li 2 O → 4Li + O 2 2BaO → 2Ba + O 2 2BaO → 2Ba + O 2

THE END