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Unformatted text preview: ple of Cadmium metal was melted by an electric heater providing 4.66 J/s of heat. If it took 6.92 minutes from the time the metal began to melt unt il it was co mpletely melted, what is the DHf (in kJ/mo le) of Cadmium ? ? J = (6.92 min) x (60 sec/min) x (4.66 J/s) = 1935 J kJ 1935 J ? ¾ = ¾¾¾¾¾¾¾¾¾¾ = 6.13 kJ/mole mo le 1 mo le Cd 35.5 g ¾¾¾¾¾ 112.4 g Cd 8 Chemistry 101 Chapter 11 PHASE DIAGRAMS
· Phase diagrams show graphical way to summarize the conditions under which the different physical states of a substance are stable. PHASE DIAGRAM FOR WATER p(atm) B pc= 218 C (Critical Point LIQUID SOLID 1.00 p3= 0.0060 GAS A (Triple Point) SOLID GAS D 0 t ( C) GAS t3 = 0.010 C 374 0 C 00 C AB = M.P. curve at different pressures; Along AB : solid liquid · AB leans slightly to the left (true for water only) Meaning: As the pressure increases, MP decreases slight ly AC = B.P. curve at different pressures; Alo ng AC : liquid gas · As the pressure increases, BP increases considerably (true for all liquids since Vapor Pressure a temperature) AD = Vapor Pressure of solid (ice) at different temperatures
· Solid can sublime (so lid ¾>gas) at p < 0.0060 atm) 9 Chemistry 101 Chapter 11 PHASE DIAGRAM FOR WATER p(atm...
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