CHEMICAL REACTIONS AND CHEMICAL EQUATIONS

• Chemical reactions - processes by which elements or compounds interact with one another to form a new compound - occurs when chemical bonds between atoms are found and broken - reactants (starting materials) transformed into new materials or substances which we refer to as products
• Combustion - example of chemical reaction that exhibits a change in temperature
• Effervescence/evolution of gas - mixing acetic acid in vinegar and baking soda - carbon dioxide escapes the mixture
• Precipitation - arises when two aqueous solutions upon mixing from an insoluble solid (precipitate)
• Types of Chemical Reactions:

  1.Synthesis Reactions (combination reactions) A+B = C

  • two or more simple substance (elements) combine to form new compounds
  • H2 (g) + O2 (g) = 2H2O (g)

  2. Decomposition Reactions A = B + C

  • a compound is broken down into simpler compounds
  • opposite of synthesis reactions
  • through heat, energy, catalyst

  3. Combustion Reaction

  • a substance react reacts with oxygen gas, releasing a large amount of energy in the form of light and heat
  • combustion of organic compounds (hydrocarbons) = formation of CO2 AND H2O
• Single Displacement reaction

  AB+C = AC+B
• Reduction-oxidation reaction


  Electrons are transferred between reactants to form ionic species
• Sodium


  Acts as reducing agent/reductant since it causes reduction of chlorine
• Chlorine


  Acts as oxidizing agent/oxidant since it caused the removal of electrons from sodium atoms
• Daniel Cell (battery)


  • Only occur when an element that does the replacement is more reactive than the element that is being replaced
• Double Displacement Reaction (double replacement reaction)

  AB + CD = AD+CB
• Double Displacement Reaction


  Occurs when two ionic substances react and exchange ions with one another
• Two types of Double Displacement Reaction:

  1.Acid-base reactions (neutralization reactions) (HCl +NaOH = NaCl + H2O)

  • combinations of an acid and a base forming a salt and water
  • combination of hydrogen ion (H+) acid and an hydroxide ion (OH-) from a base

  2. Precipitation reaction

  • happen when cation of one compound combines with the anions of another compound, forming precipitate
  • AgCl (silver chloride) - precipitate