1. One-Component System AL Chemistry Phase Equilibrium C. Y. Yeung, 05/06 __________ _______________________ melting freezing boiling condensation sublimation deposition

2. Pressure (atm) Temperature (K) 1 atm melting point curve (L + S in eqm) sublimation curve (S + V in eqm) boiling point curve (L + V in eqm) super cooling curve (L + V not at eqm, but in metastable state) Phase Diagram ref. p. 251 - 252 C. Y. Yeung p. 01

3. Each curve represent the ___________________________ C. Y. Yeung p. 02

4. Effect of changing T (at const. P) _____ e.g. P t of CO 2 = ____ atm  When P = 1 atm, CO 2 ________ at T = -78 0 C. ref. p. 254 !! C. Y. Yeung p. 03 If P is constant and above P t, T , causes first ________ at ___ and then ______ at ___. T , causes first ____________ at T b and then _________ at T m. If P is constant and below P t, T , causes ____________.

5. Effect of changing P (at const. T) _____ C. Y. Yeung p. 04 If T is constant and above T t, P , usually causes a _______ change from _______ to _______ only. If T is just above T t, the substance may go thro’ __________ as P  !

6. Pressure Temperature Note(1) : T c When T > T c, the gas cannot be ________ by applying pressure alone, ** Its behaviour approximates to an ________________.  Critical Temperature (T c )  because ______ is too great for attractive force to overcome. Substance can no longer exist in __________ state beyond T c. (________________________ is impossible!) C. Y. Yeung p. 05  T c depends on the strength of ____________ _____________ !

7. Note(2) : T t When T = T t, all the 3 phases _______ to ___________.  Triple Point Temperature (T t ) C. Y. Yeung p. 06 Pressure Temperature

8. Note(3) : ____________________ is possible! When P < 1 atm, the substance boils at a b.p. normal b.p.  ______________ ( ______ b.p.), but  ______________ (easily _______________ by heat) Useful for the purification of compounds e.g. Compound X decomposes at 60 0 C, with b.p. > 60 0 C. If we have to exact compound X from a mixture by ____________, the process must be carried out at a pressure ______________, so that X boils at a temp. < 60 0 C and it does not decompose. C. Y. Yeung p. 07

9. Note(4) : ________________ When a liquid and a vapour in eqm are “cooled rapidly”, molecules cannot be packed properly to form a _______, a state is resulted. i.e. The liquid or gas is cooled below T c but does not form the _________ yet. not the most stable state. C. Y. Yeung p. 08

10. p. 291 Q3(b) HKALE 1992 Paper 1 Q.2 (i)Point X ---- ___________ point Point Y ---- ___________ point (ii)___________ (iii) (iv)____________ occurs C. Y. Yeung p. 09

11. p. 293 Q.11 HKALE 1998 Paper 1 Q.2 (a)Point B ---- ________ point Point C ---- ________ point (b)Isothermal compression of gaseous CO 2 will not cause ___________ (________  ________). (c)(i) Keep the _________ above curve AB and the __________ below curve BD. (ii) Keep the _________ above curve ____ and the __________ above curve ____. C. Y. Yeung p. 10

12. p. 295 Q.18(a) HKALE 2001 Paper 1 Q.1 (i)AB ---- ____________ curve of ice BC ---- _______________ curve of water (ii)The temperature at which ice, liquid water and water vapour are __________________. (iii)In ice and liquid water, the intermolecular attraction is ____________________. Each H 2 O molecule can form a maximum of ______________________ with its neighbours. Ice has an _________ structure. In liquid water, ___________ motion of H 2 O molecules bring the molecules ____________________, therefore H 2 O (l) has a higher __________. C. Y. Yeung p. 11