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SingaporeChemistryQuick questions
The Particulate Nature of Matter
Quick questions on Changes of state and heating curves explained: O-Level Chemistry
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is naming the changes of state?Show answer
The six changes link the three states:
What is explaining changes with the particle model?Show answer
When a solid is heated, its particles vibrate faster. At the melting point they have enough energy to overcome the forces holding them in fixed positions, so they begin to slide and the solid melts into a liquid. On further heating the liquid particles move faster, and at the boiling point they gain enough energy to break away from one another completely and escape as a gas. Cooling reverses this: as particles lose energy they slow down, come closer, and the forces between them pull them into a liquid and then a solid.
What is reading a heating curve?Show answer
A heating curve plots temperature against time as a substance is heated steadily from solid to gas. It has a characteristic shape:
What is q1?Show answer
Name the change of state from a gas to a liquid. [1 mark]
What is q2?Show answer
Explain why the temperature does not rise while a pure solid is melting. [2 marks]
What is q3?Show answer
State two differences between evaporation and boiling. [2 marks]
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