States of matter

• What are the three states of matter ?

  Solid, Liquid and Gas
• Gas particles have the most energy and are the most spread apart with a random arrangement
• Liquid particles have more energy than solids but less than gases, and they are closer together with a random arrangement
• Solid has the least energy, particles are not moving and are arranged regularly and very closely together
• Interconversions between the three states of matter involve physical changes, not chemical changes
• Melting: solid → liquid, Freezing: liquid → solid
• Boiling: liquid → gas, Condensing: gas → liquid
• When changing from solid to liquid to gas, particles gain more kinetic energy, move around more, become more randomly arranged and further apart
• When changing from gas to liquid to solid, particles lose kinetic energy, move less, become more regularly arranged and closer together
• Diffusion is the movement of particles from an area of high concentration to an area of low concentration
• Diffusion does not occur in solids since particles cannot move from place to place, only vibrate
• Coloured solutions are diluted by adding water, because the particles of the colour diffuse to the area of low concentration, mixing with the water molecules, causing dilution to occur and the colour to become less strong
• Solvent = liquid in which a solute dissolves
• Solute = substance that dissolves in a liquid to form a solution
• Solution = mixture formed when a solute has dissolved in a solvent
• Saturated solution = solution in which no more solvent can be dissolved
• Solubility is shown as the grams of a solute that will dissolve in 100 g of water
• Solubility of solids increases when temperature increases
• Solubility of gases increases when pressure increases
• In solubility curves, mass below the line for a solute at a specific temperature indicates an unsaturated solution
• In solubility curves, mass above the line for a solute at a specific temperature indicates a supersaturated solution that is unstable
• Practical: Investigate the Solubility of a Solid in Water at a Specific Temperature

  Aim: To measure the solubility of a salt at different temperatures
• • Continue until a total of 10 cm3 of water has been added
• Results:

  • Record the solubility in a table
  • Use the results to plot a solubility curve for ammonium chloride at different temperatures
• Conclusion: The shape of the graph will indicate how the solubility varies with temperature