chemical reactions

• Chemical Reaction


  When chemicals come together to form something new
• Reactant


  The chemicals that react together
• Product


  The new substances formed in the reaction
• Effervescence


  • Bubbles of gas
• Exothermic


  When a chemical reaction gives out heat
• Endothermic


  When a chemical reaction takes in heat
• How Chemical Reactions Happen

  1. Bonds must be broken in the reactants

  2. Bonds rearrange to form bonds in the products

  3. Energy is taken in to break bonds

  4. Energy is released when bonds form
• Signs that a Reaction has Happened

  • Change in colour
  • Change in temperature
  • Production of light
  • Emission of sound
  • Smell
  • Bubbles of gas (effervescence)
• Exothermic Reactions


  • Burning coal/firewood
  • Fireworks exploding
• Endothermic Reactions


  • Sherbet on your tongue
  • Instant cold pack (sports cooling packs)
• Energy Profile Diagram


  1. Show energy transfer in a chemical reaction

  2. In an exothermic reaction, the products have less energy than the reactants

  3. In an endothermic reaction, the products have more energy than the reactants
• Collision Theory


  In order for a chemical reaction to happen, the particles must collide with each other
• Activation Energy


  The minimum amount of energy the colliding particles must have to make the product form
• Rate of a Reaction


  How fast a chemical reaction happens
• Measuring the Rate of a Reaction

  1. See how much gas is produced

  2. Monitor the temperature

  3. Monitor the appearance of the reactants and products
• Factors that Affect the Rate of Reaction

  • Temperature
  • Surface area of the reactants
  • Concentration of reactants
  • Adding a catalyst
  • Types of reactants
• The test for oxygen is that it relights a glowing splint
• The test for Carbon Dioxide is that it turns limewater milky