C3

• Avogadros constant 


  6.02 x10 23
• Moles


  Moles = Avogadros constant / Relative atomic mass
• Exothermic reaction

  • energy released to the surroundings
• Exothermic reaction


  Exothermic reaction

  
• Endothermic reaction


  Endothermic reaction

  
• endothermic

  • take in heat from surroundings
• Activation energy 


  Minimum amount of energy needed reactant particle need in order to collide with each other
• pH scale


  Measure of how acidic or alkaline a solution is, ranging from 0 to 14 with low numbers being most acidic and high numbers being most alkaline
• Neutral substances like pure water have a pH of 7, which is neither acidic nor alkaline
• Acidic substances


  • Stomach acid (pH 2)
  • Acid rain (pH 4)
• Alkaline substances


  • Washing up liquid (pH 9)
  • Bleach (pH 12)
• Measuring pH


  1. Using an indicator (chemical dyes that change color)

  2. Using a pH probe connected to a pH meter
• Indicator


  A group of chemical dyes that change color depending on the pH, some are wide range indicators like universal indicator
• pH probe and meter


  Can provide more accurate and precise pH measurements than indicators
• Acid


  Any substance that forms aqueous solutions with a pH less than 7, releasing hydrogen ions in water
• Base


  Any substance with a pH greater than 7
• Alkali


  A subgroup of bases that are soluble in water, forming hydroxide ions
• Neutralization reaction


  Reaction between an acid and a base, producing a salt and water
• Common acids


  • Hydrochloric acid
  • Sulfuric acid
  • Nitric acid
• Common bases


  • Sodium hydroxide
  • Calcium carbonate
• Types of bases


  • Metal oxides
  • Metal hydroxides
  • Metal carbonates
• Neutralization reactions


  Reactions between acids and bases
• Making soluble salts using an insoluble base


  1. Place dilute acid in beaker and heat gently

  2. Add insoluble base a little at a time

  3. Filter out excess base

  4. Evaporate solution to get crystals

  5. Filter and dry crystals
• Acid reacts with metal oxide or hydroxide


  Forms salt and water
• Acid reacts with metal carbonate


  Forms salt, water, and carbon dioxide
• Soluble salts are formed when an acid reacts with an insoluble base
• To make pure solid crystals of a soluble salt, the solution is gently heated to evaporate water, then the crystals are filtered and dried
• A water bath or electric heater should not be used to heat the solution, as this could damage the salt
• Redox reactions


  Reactions in which oxidation and reduction both take place at the same time
• Displacement reactions


  More reactive metal displacing a less reactive one
• Ionic equations


  Only show the particles that actually take place in the reaction and change in some way
• Half equations


  Show the gain and loss of electrons for each of the elements involved
• Oxidation


  Losing electrons
• Reduction


  Gaining electrons
• 'oil rig' stands for 'oxidation is loss, reduction is gain' and refers to electrons
• Redox reactions


  One substance loses electrons, another substance gains them
• Redox reaction


  • Magnesium reacting with dilute acid, magnesium atoms lose electrons to form magnesium two plus ions, hydrogen ions gain electrons to form hydrogen gas
• Spectator ions don't take part in the reaction by exchanging electrons
• In half equations, the overall charge on each side must balance
• Chemical


  chemical change, the kind of matter changes and at least one new substance with new properties is formed