Answers section
Questions 2.13 
- The changes that occur during heating and cooling can be summarized as follows.
- Identify the direction which represents heating in this diagram (whether from right to left or the other way round). -----------------------------------
- Name the physical states labelled K and L. K ----------------- L -----------
- Name the processes represented by A to D.
A------------------- B------------------- C---------------------D --------------- or ------------
- For process C, state the corresponding possible names of K. ---------------
- Explain in terms of the kinetic theory the changes that occur during process
- A ----------------------------------------------------------------------------------------
- B ----------------------------------------------------------------------------------------
- C ----------------------------------------------------------------------------------------
- D ----------------------------------------------------------------------------------------
- For some substances, the solid state changes directly to L during heating.
- Name the process in which a substance changes directly from solid to L. -----
- Name three substances which behave in the manner described. ----------------
- State the process that involves change from L directly to solid. -------------------
- What is the general name of the solid formed directly from L? --------------------
Answers to Questions 2.13 
-
- From left to right.
- K = Liquid; L = Gas
- A = Melting or fusion; B = Boiling; C = Condensation; D = Freezing
- Condensate, distillate
- A: As heat is absorbed, the particles vibrate more violently and break off from their regular arrangement at fixed positions. They become free to move about randomly and acquire liquid state, where they still experience some weak attractions towards one another.
- B: The weak attractions between particles are completely overcome so they move freely in all directions; a gaseous state is achieved.
- C: Heat is lost, the particles move closer to one another and experience some weak attractions, forming the liquid state.
- D: As more heat is lost, the particles become closely packed and held together in a regular arrangement. They vibrate at fixed positions.
- For some substances, the solid state changes directly to L during heating.
- Sublimation
- Anhydrous ammonium chloride, anhydrous iron (III) chloride, iodine, carbon (IV) oxide
- Deposition
- Sublimate