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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.
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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 • 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
Temperature (ºC) Melting completes Melting starts Melting point (69°C) LIQUID SOLID +LIQUID SOLID Temperature remains constant Time from start (min) D C B A 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:
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 • 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
temperature (ºC) 74ºC X Y W 0 time from start (min) 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:
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
Tempt / 0C 120 60 40 Time from start / min Exercise: Combination of melting & boiling curve completely gas Mixture of liquid & gas boiling point, 120oC Mixture of solid & liquid completely liquid completely solid melting point, 60oC