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Changes in States

Changes in States. Freezing….Boiling…. Sublimation…. Condensation……Evaporation. Freezing. To explain the movement of particles in the process of _____________. Freezing  (a)    F reezing : ___________ state  __________ state. freezing. liquid. solid. Liquid particles.

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Changes in States

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  1. Changes in States Freezing….Boiling…. Sublimation…. Condensation……Evaporation

  2. Freezing • To explain the movement of particles in the process of _____________. Freezing •  (a)   Freezing : ___________ state  __________ • state. freezing liquid solid Liquid particles Solid particles

  3. Explanation using KPT drops • When a liquid is cooled, the temperature ________ until its freezing point is reached. • During freezing, the liquid particles will lose the heat energy to the surroundings as they ____________ to take up ________ and________ positions in the solid. Note: For all pure substances, the freezing point is the same as the melting point. Slows down fixed orderly

  4. temperature (ºC) LIQUID temperature remains constant SOLID freezing point (=melting point) LIQUID + SOLID freezing starts freezing completes time from start (min) Reading a Graph on Freezing

  5. Reading a graph on freezing Graph shows how temperature of substance changes with time during melting when it is heated steadily. 1. PQ - the substance is completely ______________. 2. Point Q - ____________ begins at _________. ( The ______ drop of liquid begins to form a ______). 3. QR - ________ continues to take place. The substance exists as a ________ of _____ and __________. 4. Point R – The last drop of _________ will change into a ______ 5. RS – The substance is completely __________ liquid freezing 690C solid first freezing mixture solid liquid liquid solid solid

  6. Think…….. Why does the temperature remain constant between QR even though the substance is continuously cooled? Ans: During cooling heat is given out by particles as they take up fixed positions is equal to heat loss from the surround during cooling.

  7. Sublimation solid • It is a process where a _________ when heated changes directly into a ________ without going through a _________ state. • During sublimation, heat energy is _________ to _______________________. • Examples of substance that sublimes: gas liquid absorbed forces of attraction • Dry ice • Iodine (crystals to purple vapour) • Moth balls • Ammonium chloride, NH4Cl

  8. Condensation Gas It is a process where a _________ is changed into a ______ or _______. During condensation, heat energy is _________ to form back the _________________________. solid liquid given out forces of attraction

  9. Evaporation gas It is a process where a _______ is changed into a ______ but it occurs _____ the boiling point of the liquid. During evaporation, heat energy is ___________ to ____________________________. liquid below absorbed break the forces of attraction

  10. Differences between evaporation and boiling Some liquids whose boiling points are not far from the room temperature tends to evaporate easily. Such liquid are called _________ liquids. E.g nail polish remover ; perfumes volatile

  11. Summary Melting ; Heat energy is _______ _____________ ; Heat energy is _______ (2) (4) (3) (5)

  12. Predicting states Example: What would be the state of substance X at room temperature given the mp is 400C and bp is 1090C. Ans: Everyone look on board!

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