Changes In States

Melting To explain the movement of particles in the process of _____________.  Melting  (a)   Melting: ___________ state  __________ state.   melting solid liquid liquid solid

Explanation using KPT absorb energy vibrate overcome When a solid is heated, the solid particles will ________ the heat and gain ________ to ___________ more vigorously. When enough heat is applied, the solid particles vibrates so vigorously that they are able to ___________ the_______________________ holding the solid particles. When this happen, the solid has turned into a _________; ________ has taken place. energy vibrate overcome forces of attraction liquid melting

Reading a Melting Curve Note: This curve is only true for a pure compound An experiment can be carried out and the result of the melting can be plotted as shown: Temperature (ºC) Melting starts Temperature remains constant Melting completes Time from start (min) Melting point (69°C) SOLID SOLID + LIQUID LIQUID A B C D

Reading the melting curve Graph shows how temperature of substance changes with time during melting when it is heated steadily.   1. AB - the substance is completely ______________. 2. Point B - ____________ begins at _________. ( The first drop of ________ appears). 3. BC - ________ continues to take place. The substance exists as a ________ of _____ and __________. 4. Point C – The last drop of _________ is formed. 5. CD – The substance is completely __________ ( )  solid melting 690C liquid melting mixture solid liquid liquid liquid molten

Think…… Why does the temperature remain constant between B and C even though heat is continuously supplied? Ans: The heat is used to overcome the forces of attraction holding the solid particles instead of causing the temperature to rise.

Boiling To explain the movement of particles in the process of _____________. Boiling  (a)   Melting: ___________ state  __________ state.   boiling liquid gaseous gaseous liquid

Explanation using KPT absorb energy vibrate overcome When a liquid is heated, the liquid particles will ________ the heat and gain ________ to ___________ more vigorously. When enough heat is applied, the liquid particles vibrates so vigorously that they are able to ___________ the_______________________ holding the liquid particles. When this happen, the liquid has turned into a _________; ________ has taken place. energy vibrate overcome forces of attraction gas boiling

Reading a Boiling Curve Note: This curve is only true for a pure compound An experiment can be carried out and the result of the melting can be plotted as shown: temperature (ºC) time from start (min) X Y 74ºC W

Reading the boiling curve Graph shows how temperature of substance changes with time during melting when it is heated steadily.   1. WX - the substance is completely ______________. 2. Point X - ____________ begins at _________. ( The first drop of ________ appears). 3. XY - ________ continues to take place. The substance exists as a ________ of _____ and __________. 4. Point Y – The last drop of ________change into _________ state. 5. Beyond Y – The substance is completely __________ liquid boiling 740C gas boiling mixture gas liquid liquid gaseous gaseous

Exercise: Combination of melting & boiling curve Time from start / min Tempt / 0C 40 60 120 completely gas Mixture of liquid & gas boiling point, 120oC Mixture of solid & liquid completely liquid completely solid melting point, 60oC