Purity, formulations and chromatography

• What is a pure substance?

  A pure substance is a single element or compound, not mixed with any other substance.
• What happens to pure substances at specific temperatures?

  They melt and boil at specific temperatures.
• How can melting and boiling points be used in chemistry?

  They can be used to distinguish pure substances from mixtures.
• How is a pure substance defined in everyday language?

  A pure substance is one that has had nothing added to it, making it unadulterated and in its natural state.
• Give an example of a pure substance.

  Pure milk is an example of a pure substance.
• What is a formulation?

  A formulation is a mixture that has been designed as a useful product.
• Why are many products considered complex mixtures?

  Because each chemical in them has a particular purpose.
• How are formulations created?

  They are made by mixing components in carefully measured quantities to ensure required properties.
• What are some examples of formulations?

  • Fuels
  • Cleaning agents
  • Paints
  • Medicines
  • Alloys
  • Fertilisers
  • Foods
• What is chromatography used for?

  Chromatography is used to separate mixtures and provide information to help identify substances.
• What are the two phases involved in chromatography?

  The two phases are the stationary phase and the mobile phase.
• What does the separation in chromatography depend on?

  Separation depends on the distribution of substances between the stationary and mobile phases.
• What is the formula for calculating the Rf value?

  Rf value = distance moved by substance ÷ distance moved by solvent.
• How do different compounds behave in chromatography?

  Different compounds have different Rf values in different solvents, aiding in their identification.
• What is the behavior of a pure compound in chromatography?

  A pure compound will produce a single spot in all solvents.
• What is paper chromatography?

  Paper chromatography is an analytical technique separating compounds by their relative speeds in a solvent as it spreads through paper.
• How does solubility affect the movement of substances in paper chromatography?

  The more soluble a substance is, the further up the paper it travels.
• What does chromatography separate in colored substances?

  Chromatography separates different pigments in a colored substance.
• What is a pigment?

  A pigment is a solid, colored substance.