chemistry paper 3

    Cards (167)

    • What does the particle theory describe about states of matter?
      Particles are described as hard spheres
    • What are the characteristics of particles in different states of matter?
      • Solid: close together, regular patterns, vibrate about fixed positions, least stored energy
      • Liquid: close together, move around each other, moderate stored energy
      • Gas: far apart, random, fast in all directions, most stored energy
    • What are state changes in matter?
      Interconversions between states of matter
    • What happens during a state change?
      Energy is transformed, arrangement and movement change
    • What begins to happen at a substance's melting point?
      It begins to melt if energy is added
    • What occurs at a substance's boiling point?
      It begins to boil if energy is added
    • What is evaporation?
      Liquid to gas below boiling point
    • What is an element?
      A substance made of one type of atom
    • What do all atoms in an element have in common?
      Same mass number and atomic number
    • What is a compound?
      A substance made of different elements bonded together
    • What is the difference between atoms and molecules?
      Atoms exist as individual units or molecules
    • What is air composed of?
      Elements and compounds like N₂ and H₂O
    • What defines a pure substance in chemistry?
      • Contains only one element or compound
      • Examples: pure water, pure hydrogen
      • Impure substances: salt water
    • What is the purpose of filtration?
      To separate insoluble substances from liquids
    • How does filtration work?
      Filter paper has tiny pores for separation
    • What is crystallisation used for?
      • To produce solid crystals from a solution
      • Involves heating to create a saturated solution
      • Crystals form as the solution cools
    • What is the role of a condenser in distillation?
      To cool and condense vapour back to liquid
    • What is the process of simple distillation?
      1. Heat solution
      2. Solvent boils
      3. Vapour passes into condenser
      4. Vapour cools and condenses
      5. Solution becomes more concentrated
    • What is fractional distillation used for?
      • To separate miscible liquids
      • Based on different boiling points
      • Vapour condenses at different heights in column
    • What is the pH of acids?
      Less than 7
    • What do acids release in solution?
      Hydrogen ions, H⁺(aq)
    • What is the pH of alkalis?
      More than 7
    • What do alkalis release in solution?
      Hydroxide ions, OH⁻(aq)
    • What is the pH scale?
      • Measures acidity or alkalinity
      • Ranges from 0 to 14
      • Neutral is pH 7
    • What is a concentrated solution?
      Has a greater amount of dissolved solute
    • How can you dilute a solution?
      Add more water to it
    • What is the ratio of acid to water in a mixture of 1cm³ of acid and 4cm³ of water?
      1:4
    • What is the new concentration if 1cm³ of 2 g/dm³ acid is added to 4cm³ of water?
      0.33 g/dm30.33 \text{ g/dm}^3
    • What does the indicator colour match to?
      A colour chart showing pH
    • How does the strength of an acid affect its pH?
      The strength and concentration determine the pH
    • What is the difference between concentrated and dilute solutions?
      Concentrated has more solute particles
    • How can you change a concentrated solution to a dilute solution?
      • Add more water to it
    • How can you make a dilute solution more concentrated?
      • Add more solute
      • Evaporate some water
    • What is the ratio of acid to water when 1cm³ of acid is added to 4cm³ of water?
      The ratio is 1:4
    • What is the new concentration when 1cm³ of 2 g/dm³ acid is diluted with 4cm³ of water?
      The new concentration is 0.4 g/dm³
    • Which acids are considered strong acids?
      Hydrochloric acid and sulfuric acid
    • What happens to strong acids in solution?
      They fully dissociate into ions
    • What is the dissociation equation for hydrochloric acid?
      HCl(aq) → H⁺(aq) + Cl⁻(aq)
    • What is the dissociation equation for sulfuric acid?
      H₂SO₄(aq) → 2H⁺(aq) + SO₄²⁻(aq)
    • How does the concentration of hydrogen ions affect pH?
      Higher concentration lowers the pH