States of matter & mixtures

• What are the three states of matter?

  Solid, liquid, and gas
• What occurs at the melting point?

  Melting and freezing take place
• What is the process of a solid turning into a liquid called?

  Melting
• What is the process of a liquid turning into a solid called?

  Freezing
• What occurs at the boiling point?

  Boiling and condensing take place
• What is the process of a liquid turning into a gas called?

  Boiling
• What is the process of a gas turning into a liquid called?

  Condensing
• How can the states of matter be represented in a simple model?

  • Particles are represented by small solid spheres
• Which state of matter has the most energy in its particles?

  Gas
• How does the energy of liquid particles compare to solid and gas particles?

  Liquid particles have more energy than solid particles but less than gas particles
• Which state of matter has the least energy in its particles?

  Solid
• What are the characteristics of state changes in matter?

  • State changes (melting, boiling, freezing, condensing) are physical changes
  • They involve forces between particles but do not change the particles themselves
• What distinguishes chemical changes from physical changes in states of matter?

  Chemical changes result in the formation of a new product
• How does particle theory explain state changes?

  • Energy needed to change state depends on the strength of forces between particles
  • The nature of particles depends on the type of bonding and structure of the substance
  • Stronger forces lead to higher melting and boiling points
• How can you predict the physical state of a substance given its melting and boiling points?

  By comparing the temperature to the melting and boiling points
• What physical state will a substance be at temperatures below its melting point?

  Solid
• What physical state will a substance be at temperatures above its melting point but below its boiling point?

  Liquid
• What physical state will a substance be at temperatures above its boiling point?

  Gas
• What is the difference between the use of 'pure' in chemistry and its everyday use?

  In chemistry, 'pure' refers to a single element or compound, while in everyday language, it means a substance that has had nothing added to it.
• What are the characteristics of a mixture and a pure substance in chemistry?

  • A mixture consists of 2 or more elements or compounds not chemically combined.
  • The chemical properties of each substance in a mixture remain unchanged.
  • A pure substance is a single element or compound, not mixed with any other substance.
• How is a pure substance defined in everyday language?

  A pure substance is defined as one that has had nothing added to it, making it unadulterated and in its natural state, such as pure milk.
• How can melting point data be used to distinguish between pure substances and mixtures?


  Pure substances have a sharp melting point, while mixtures melt over a range of temperatures.
• What is the melting point behavior of pure substances compared to mixtures?


  Pure substances melt at specific/exact temperatures, while mixtures do not.
• What are the experimental techniques for separation of mixtures?

  • Simple distillation
  • Fractional distillation
  • Filtration
  • Crystallisation
  • Paper chromatography
• What is fractional distillation used for?

  Fractional distillation is used to separate a pure liquid from a mixture of liquids based on different boiling points.
• How does fractional distillation work with ethanol and water?

  Ethanol has a lower boiling point than water, so it evaporates first, and its vapor is cooled and condensed to form a pure liquid.
• What is the sequence of events in fractional distillation?

  1. Heating

  2. Evaporating

  3. Cooling

  4. Condensing
• What is simple distillation used for?

  Simple distillation is used to separate a solvent from a solution, such as producing water from a salt solution.
• Why is simple distillation effective for separating a solvent from a solution?

  It is effective because the dissolved solute has a much higher boiling point than the solvent.
• What happens to the solution during simple distillation?

  When heated, the solvent vapor evaporates, and the remaining solution becomes more concentrated in solute as the solvent decreases.
• How is filtration used to separate a precipitate from a solution?

  Filtration separates the precipitate by leaving it on the filter paper while allowing the solution to pass through.
• What is the process of crystallisation used for?

  Crystallisation is used to separate a soluble salt from the solution it is dissolved in.
• What are the steps involved in crystallisation?

  1. Warm the solution in an open container to allow solvent evaporation.

  2. Allow the solution to cool.

  3. Collect and dry the crystals that form.
• 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.
• How does separation in chromatography depend on the substances?

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

  Rf value = distance moved by substance / distance moved by solvent
• How can Rf values help in identifying compounds?

  Different compounds have different Rf values in different solvents, which can help identify the compounds.
• What is the difference in chromatogram appearance between pure and impure substances?

  A pure substance will produce a single spot on a chromatogram, while an impure substance will show more than one spot.
• How can substances be identified by comparison on a chromatogram?

  By carrying out chromatography with both the known substance and the test substance on the same paper, if both spots are at the same height, they are the same substance.