Chapter 2 - Experiment Technique & Method of Purification

Cards (31)

  • The purity of the product can be determined by comparing its melting point
  • If the melting points are identical, it is likely that the compound has been isolated pure.
  • Crystallization from solvents other than water may also result in crystals being formed.
  • Precipitation reactions involve adding a precipitating agent to a solution containing a soluble ion or molecule.
  • Crystallization from solvents other than water may also be used to isolate compounds.
  • Element
    Substance that cannot be broken down into simpler substances by chemical means
  • Compound
    Substance formed when two or more different elements are chemically combined in a fixed proportion
  • Mixture
    Combination of two or more substances that are not chemically combined and can be separated by physical means
  • Mixtures
    • Easily separated
    • No fixed ratio/amount
    • Properties remain unchanged
  • Compound
    • Chemically mixed
    • Hard to separate
    • Fixed ratio/amount
    • Properties change
  • Solution
    Homogeneous mixture of a solute dissolved in a solvent
  • Solute
    Substance dissolved in a solvent
  • Solvent
    Dissolving medium in a solution
  • Heterogeneous Mixtures
    distinguishable
  • Colloid
    Mixture with insoluble tiny particles spread evenly throughout a liquid
  • Suspension
    Mixture with insoluble solid spread throughout a liquid but quickly settles to the bottom
  • Example of Suspension
    • Solid + liquid
    • Insoluble liquid in liquid (e.g. oil in water)
  • Filtration
    Separate insoluble solid from liquid
  • Buchner funnel
    1. Flask connected to suction pump
    2. Faster
  • Decanting
    Pour liquid away, sedimentation, slow and inefficient
  • Sieving
    Smaller particles pass through pores
  • Sublimation
    Solid to gas (e.g. sulfur, iodine), only for substances that can undergo sublimation
  • Centrifugation
    Separation based on density using centrifugal forces
  • Simple distillation
    Separate solvent from solution based on boiling point
  • Fractional distillation
    Separate miscible liquids based on boiling point
  • Crystallization
    Concentrate solution until saturated, then crystals form
  • Separating funnel
    Separate immiscible liquids
  • Magnetic separation
    Separate magnetic from non-magnetic substances
  • Chromatography
    Separate substances based on solubility and capillary action
  • Rf value
    Distance travelled by substance/distance travelled by solvent
  • Homogeneous
    indistinguishable