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Chemical Reactions. Objectives. 1) Write and balance equations 2) Identifying the types of reactions. Reactants and Products. Gallium + Sulfuric acid → Gallium Sulfate + Hydrogen Reactants- left side of the arrow -starting materials Products-right side of the arrow
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Objectives • 1) Write and balance equations • 2) Identifying the types of reactions
Reactants and Products Gallium + Sulfuric acid → Gallium Sulfate + Hydrogen • Reactants- left side of the arrow -starting materials • Products-right side of the arrow -the substance made, produced • 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. • 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) • 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. Br2 I2 N2 Cl2 H2 O2 F2
Balancing Example • Ga + H2SO4 → Ga2(SO4)3 + H2 Balanced: 2Ga + 3H2SO4 → Ga2(SO4)3 + 3H2
Identifying Reactions • The five types of reactions: -Synthesis or Combination -Single Replacement -Double Replacement -Combustion -Decomposition (6 types)
Synthesis • element + element → compound • Occurs when two or more elements are combined to form a new substance • Also called Combination A + B AB
Synthesis or Combination • Example: 2 Na + Cl2 → 2NaCl Jayhawk says: Here’s an example of synthesis: + = Rivalry
Single Replacement • Occurs when one element displaces another in a compound. • A + BC → B + AC element + compound → element + compound
Single Replacement Example: 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 • AB + CD → AD + CB • compound + compound→compound +compound • Never put two metals together
Double Replacement Example: 2NaCl + Li2O → Na2O + 2LiCl Did you know? Double replacement is also referred to as metathesis.
Combustion • Hydrocarbon + O2 → H2O + CO2
Combustion Example: C4H8 + O2 →H2O + CO2
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. • compound → 2 or more substances • → AB A + B
Decomposition • There are 6 different types of decomposition Did you know? You might also know decomposition by analysis.
Electrical Decomposition AB → A + B 2NaCl → 2Na + Cl2
Decomposition: Oxy-Acid Oxy-Acid → Water + Nonmetal Oxide H2SO4 → H2O + SO3 Examples: HNO3 H3PO4 HClO2
Decomposition: Metallic Hydroxide Metallic Hydroxide → Metal Oxide + Water 2LiOH → Li2O + H2O Fe(OH)2 → FeO + H2O
Decomposition: Metallic Carbonate Metallic Carbonate → Metal Oxide +Carbon Dioxide MgCO3 → MgO + CO2 Fe2(CO3)2 → Fe2O3 + 3CO2
Decomposition: Metallic Chlorate Metallic Chlorate → Metal Chloride + Oxygen 2LiClO2 → 2LiCl + 3O2 Ca(ClO3)2 → CaCl2 + 3O2
Decomposition: Metallic Oxide Metallic Oxide → Metal + Oxygen 2Li2O → 4Li + O2 2BaO → 2Ba + O2