C2 - States of matter and mixtures

• Solid

  • Regular
  • Fixed position
  • Vibrate about a fixed position
  • Low kinetic energy
• Liquid

  • Random arrangement
  • Move past each other (touching)
  • Take shape of the container
  • Flow (Medium kinetic energy)
• Gas

  • Move in random directions
  • Spread out in all directions
  • High kinetic energy
• Solid to Gas ---> Sublimination
• Gas to Solid ---> Deposition
• Melting

  energy used to weaken intermolecular forces
• Evaporating

  energy used to completely weaken intermolecular forces
• Pure Substance = all the same type of substance (1 type of element or compound)
• Mixture = more than 1 type of substance (not chemically bonded)
• Flat line of a graph = Pure Substance
• Not flat line on graph = Not pure substance (Mixture)
• Filtration 


  separates insoluble solids from liquids/solutions

  insoluble particles are too big to go through filter paper
• Crystallisation


  separates a soluble solid from a solution by evaporation

  1. heat solution gently on Bunsen burner (evaporating basin)
  2. evaporate half/third of the solution
  3. leave to cool
• Simple Distillation


  separates mixture of 2 liquids based on boiling points (eg. ethanol and water)

  1. heat mixture (liquid with lowest bp evaporates first)
  2. gas then condenses in condenser back to liquid
• Fractional Distillation

  separates more than 2 liquids based on boiling point (crude oil)

  1. Heat mixture gently
  2. Temperature gradients forms (hotter at bottom than top)
  3. Lowest bp will condense in condenser, at top of fractionating column
• Chromatography


  separates substances based on their solubility in different solvents

  1. draw line at bottom of paper with pencil (insoluble, wont move with ink up paper)
  2. Place cross on line with pencil then add substance on cross
  3. Add into beaker with solvent (don't touch solvent with substance, it washes away)
  4. MOBILE PHASE = Solvent
  5. STATIONARY PHASE = Paper
• Chromatography


  More dots = more soluble 

  Less dots = less soluble

  No dots = insoluble in that particular solvent

  Rf value (closer to 1 = more soluble)  = divide substance distance by solvent distance
• Potable Water

  Making water safe to drink
• Potable Water (Desalination)


  Disadvantage = takes up lots of energy

  1. Heat water to evaporate
  2. Water rises and condenses back to liquid
• Potable Water (Water from lakes/reservoirs)


  1. Screening = big mesh wire to sieve out big debris
  2. Sedimentation = insoluble medium-sized debris sink to bottom of tank
  3. Filtration = small insoluble bits are filtered using iron sulfate
  4. Chlorination = Chlorine added to kill microbes
• Chemical Analysis

  Water must be pure to stop false results