Topic 3 - chemical changes

Cards (20)

  • pH scale
    • Shows how acidic or alkaline a substance is
    • 0-6 is acidic
    • 7 is neutral
    • 8-14 is alkaline
  • Alkali
    • Soluble base
    • Can neutralize an acid
  • Dissociation
    1. Acids split up into hydrogen ions (H+)
    2. Alkalis split up into hydroxide ions (OH-)
  • Strong vs Weak acids/alkalis
    • Strong - completely dissociate
    • Weak - partially dissociate
  • Neutral pH has equal concentrations of H+ and OH- ions
  • Common acids
    • Hydrochloric acid (HCl)
    • Nitric acid (HNO3)
    • Sulfuric acid (H2SO4)
  • Common alkalis
    • Sodium hydroxide (NaOH)
    • Potassium hydroxide (KOH)
    • Calcium hydroxide (Ca(OH)2)
  • Indicator
    • Used to test if a substance is acidic or alkaline
    • Methyl orange, phenolphthalein, litmus paper, universal indicator
  • Testing for gases
    1. Hydrogen - squeaky pop with lit splint
    2. Carbon dioxide - bubbled through, turns limewater cloudy
    3. Oxygen - relights glowing splint
  • Neutralization
    Reaction of an acid and base to form a salt and water
  • Acid reactions
    1. Acid + metal oxide/hydroxide = salt + water
    2. Acid + metal = salt + hydrogen
    3. Acid + metal carbonate = salt + water + carbon dioxide
  • Salt
    Product formed when an acid and base react
  • Solubility of salts
    • Soluble - nitrates, most chlorides, most sulfates
    • Insoluble - silver/lead chlorides, lead/barium/calcium sulfates, most carbonates, most hydroxides
  • Making copper sulfate
    1. React copper oxide with sulfuric acid
    2. Add excess copper oxide
    3. Filter off unreacted copper oxide
    4. Crystallize to get pure copper sulfate
  • Titration
    Controlled addition of acid/base to determine exact amount needed
  • Electrolysis
    Using electricity to split up ionic compounds
  • Electrolysis setup
    1. Positive anode, negative cathode
    2. Ionic compound as electrolyte (molten or dissolved)
  • Oxidation and Reduction
    • Oxidation - loss of electrons at anode
    • Reduction - gain of electrons at cathode
  • Electrolysis of dissolved ionic compounds
    Less reactive ion is given off (e.g. hydrogen over sodium, chlorine over hydroxide)
  • Half equations describe what happens to each ion during electrolysis