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Pure substances , properties

Pure substances , properties. Matter. mixtures. Pure substances. Contain only one type of particle. heterogeneous. homogeneous. compounds. elements. Suspension. Colloid. Solution. ✗. ?. Contain only one type of particle. Pure substances. compounds. elements.

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Pure substances , properties

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  1. Pure substances, properties

  2. Matter mixtures Pure substances Contain only one type of particle heterogeneous homogeneous compounds elements Suspension Colloid Solution ✗ ?

  3. Contain only one type of particle Pure substances compounds elements At least two types of atoms, that have chemically combined  Can be separated into constituent elements Only one type of atom (there may be more than one of the same kind!)  Impossible to separate into other substances with chemical separation techniques. Hydrogen Oxygen Oxygen

  4. Work book page 14 # 1

  5. Periodic table of elements name Atomic number Atomic symbol Atomic weight

  6. Notes pure substances • Practice page 14 No2 and 3

  7. Identifying pure substances: Using properties that are specific to asubstance or a small group of substances. Characteristic Properties Non Characteristic Properties: • All substances have these properties • Mass - temperature • shape - state of matter

  8. Characteristic properties 1. Physical properties 2. Chemical properties During course of identification process substance reacts with another substance and will change • No change of the identity / nature of the substance during test process

  9. Physical properties: Melting point • The temperature at which a solid becomes a liquid (or a liquid becomes a solid) Melting point water: 0 °C Melting point ethanol: - 117 °C

  10. Physical properties: Boiling point • The temperature at which a liquid becomes a gas (or a gas becomes a liquid) Boiling point water: 100 °C Boiling point ethanol: 78 °C

  11. Physical properties: solubility • Maximum amount of solute, that can be dissolved in a given volume of solvent • Expressed in units of concentration g/L, %m/v, %m/m or %v/v

  12. Physical properties: density • Do they have the same weight? air water steel No! Density = Mass per unit volume (in g/mL): I always indicate how much 1 ml of the substance weighs.

  13. Notes on characteristic physical properties

  14. Practice 1. A rock with the volume of 22 ml weighs 37.4 g; what is its density? 2. The mass of a plastic spoon 7.5 g and its volume is 3 ml; what is its density? 3. The density of silver is 10.4 g/ml. If a sample of pure silver has a volume of 13 ml, what is its mass?

  15. Characteristic Chemical Properties • Help us identify a substance but may changethe nature of the substance during the process.  • Ex: Reaction to litmus paper, Reaction to cobalt Chloride Paper, Reaction to limewater, Reaction to a glowing splint, reaction to a burning splint, reaction to an open flame.

  16. Reaction to litmus paper • Can identify if a substance is acidic or basic. Acid Base

  17. Reaction to cobalt chloride paper • Turns pink in the presence of water. no water with water

  18. Reaction to limewater • Turns Cloudy in the presence of CO2

  19. Reaction to glowing splint • Splint reignites in the presence of oxygen A pair of bellows uses the same principal to reignite a fire

  20. Reaction to burning splint • An explosion will occur in the presence of hydrogen. Hindenburg in 1937 http://www.youtube.com/watch?v=1PLH4H7Mjl8

  21. Reaction to an open flame The color of the flame may indicate the presence of certain substances. Ba Na K

  22. Notes characteristic properties

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