3.2: Chem. Reac. and Naming of Ionic and Covalent Compound

• Chemical Reaction


  A chemical change in which one or more substances are destroyed and one or more new substances are created
• Parts of a Chemical Reaction

  Reactants → Products
• Reactants


  Substances that are destroyed by the chemical change (bonds break)
• Products


  Substances created by the chemical change (new bonds form)
• Arrow (→)


  Read as "yields"
• Other symbols in chemical reactions


  • (s) = solid
  • (l) = liquid
  • (g) = gas
  • (aq) = aqueous solution (the substance is dissolved in H2O)
  • "+" separates two or more reactants or products
  • "→" yield sign separates reactants from products
• Evidence for a Chemical Reaction


  • Evolution of light or heat
  • Temperature change (increase or decrease) to the surroundings
  • Formation of a gas (bubbling or an odor) other than boiling
  • Color change (due to the formation of a new substance)
  • Formation of a precipitate (a new solid forms) from the reaction of two aqueous solutions
• Word Equations


  Statements that indicate the reactants and products in a chemical reaction
• Skeleton Equation


  Uses chemical formulas rather than words to identify the reactants and products of a chemical reaction
• Conservation of Mass


  During a chemical reaction, atoms are neither created nor destroyed
• Properties that are conserved during chemical reactions


  • Mass
  • Types of atoms
  • Number of each atom
• Properties that are not conserved during chemical reactions


  • Color
  • Physical state (solid, liquid, gas)
  • Volume
  • Number of moles of reactants/products
• Types of Chemical Reactions


  • Single Replacement (Displacement) (Redox)
  • Double Replacement (Displacement) (Metathesis)
  • Synthesis (Combination)
  • Decomposition
  • Combustion
• Single Replacement Reaction


  A single uncombined element replaces another element in an ionic compound. There are two reactants and two products.
• Activity Series


  Elements with higher activities replace elements with lower activities during a single-replacement reaction, but not vice versa
• Activity Series for Metals

  • Li
  • Rb
  • K
  • Ba
  • Ca
  • Na
  • Mg
  • Al
  • Mn
  • Zn
  • Cr
  • Fe
  • Ni
  • Sn
  • Pb
  • H
  • Cu
  • Hg
  • Ag
  • Pt
  • Au
• Activity Series for Nonmetals

  • F
  • Cl
  • Br
  • I
• Predicting the Products of Single Replacement Reactions

  1. Write the reactants

  2. Identify the cation and anion of the reactant that is a compound

  3. Use the activity series to see if the single element will replace one of the elements in the compound

  4. Identify the reactant that is the element. Determine its charge when it becomes an ion

  5. Perform criss-cross to predict the new compound on the products side of the reaction

  6. Write both new products

  7. Balance the reaction
• Single Replacement Between Metals and Water


  Some metals have a higher activity than hydrogen and can replace it in a single replacement reaction. In these reactions, you may think of water (H2O) as H(OH).
• Double Replacement Reaction


  Parts of two aqueous ionic compounds switch places to form two new compounds. There are two reactants and two products.
• Conditions for a double replacement reaction to occur


  • A solid precipitate is produced
  • A gas is produced
  • Water is produced
• Soluble compounds


  Compounds that break down when put in water
• Insoluble compounds


  Compounds that do NOT break down when put in water
• Predicting the Products of Double Replacement Reactions

  1. Write the two reactants (both are ionic compounds)

  2. Identify the cations and anions in both of the compound reactants

  3. Pair up each cation with the anion from the other compound

  4. Write the formula for each product using the criss-cross method

  5. Write the complete equation for the double replacement reaction

  6. Balance the equation

  7. Use the solubility rules chart to figure out which product is a precipitate (s) and which product is an aqueous solution (aq)
• Synthesis Reaction


  Two or more simple substances (the reactants) combine to form a more complex substance (the product)
• Types of Synthesis Reactions


  • Element A + Element B → Compound
  • Element + Compound A → Compound B
  • Compound A + Compound B → Compound C
• Metallic and nonmetallic elements react to form ionic compounds. The resultant compound should be charge balanced by the criss-cross method.
• Nonmetals react with each other to form covalent (molecular) compounds. You should be able to draw a valid Lewis Structure for the product.
• Synthesis Reactions of Nonmetals


  • 2H2 + O2 → 2H2O
  • H2 + O2 → H2O2
• Decomposition Reaction


  A more complex substance (the reactant) breaks down into two or more simple parts (products). Synthesis and decomposition reactions are opposites.
• Decomposition of a compound produces two or more elements and/or compounds. The products are always simpler than the reactant.
• Electrolysis of Water


  An electrical current can be used to chemically separate water into oxygen gas and hydrogen gas
• Combustion Reactions


  All involve oxygen (O2) as a reactant, combining with another substance. All combustion reactions are exothermic.
• Characteristics of Combustion Reactions

  • Complete combustion of a hydrocarbon always produces CO2 and H2O
  • Incomplete combustion of a hydrocarbon will produce CO and possibly C (black carbon soot) as well
• Any synthesis reaction which involves O2 as a reactant is also considered to be a combustion reaction
• Classify these reactions


  • C4H8 + 6O2 → 4CO2 + 4H2O (Combustion)
  • HCl + NaOH → H2O + NaCl (Double Replacement)
  • 2KNO3(s) → 2KNO2(s) + O2(g) (Decomposition)
  • 2Ag + S → Ag2S (Synthesis)
  • MgCO3(s) → MgO(s) + CO2(g) (Decomposition)
  • Cl2 + 2KBr → 2KCl + Br2 (Single Replacement)
• The combustion of a metal always produces a metal oxide
• Subscript


  Affects only the element to the left of the subscript
• Coefficient


  Propagates to the right through the entire compound
• Counting atoms


  • SnO2 + 2H2 → Sn + 2H2O
  • 2 C4H10 + 13 O2 → 8 CO2 + 10 H2O
  • Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
  • 3Pb(NO3)2 + 2AlCl3 → 3PbCl2 + 2Al(NO3)3