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

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

Explanation using KPT drops until its freezing point is reached. 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

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

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

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.

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

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

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

Differences between evaporation and boiling 1. Occurs at the surface of liquid 1. Occurs in the whole liquid 2. Occurs over a range of temperature 2. Occur at fixed temperature e,g water boils at 100 degree celsius 3. No bubbles are formed 3. Bubbles are formed within the liquid 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

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

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!