2 Heating/cooling curves: Heat of vaporization potential energy increases kinetic energy remains the same Heat of fusion potential energy increases kinetic energy remains the sameAnswers to odd questions page 47-48Sublimation is when a solid goes directly to a gas without passing through the liquid phase.
3 K = C + 273C = K - 273Answers to odd questions page 49
6 Heat of fusion is the amount of energy needed to melt one gram of ice into water at 0 degrees Celsius343 J / g
7 Heat of vaporization is the amount of heat needed to evaporate 1 gram of water at 100 degrees CelsiusHf = 2260 J /g
8 Ex: 25 grams of water are cooled from 20 oC to 10 oC What is the # of joules of heat energy released?It involves a change in temp so use the formulaQ = M x C x (change in T)M = 25 grams; C = 4.18 J/g x oC Change in T = 10Answer = 1045 JEx: What are the total # of Joules needed to heat 150g of ice to water at0 oC. No temp change and ice to water means heat of fusion.Hf = 334 J/g ; Mass = 150 g Answer: 334J x 150 = 50100JAnswers to odd questions pageEx : How many Joules of heat are needed to vaporize 100g of water to vapor at 100 oC. No temp. change and 100 oC.Hv = 2260 J/g ; Mass = 100 gAnswer: 2260J x 100 = J
9 Kinetic Molecular Theory Postulates of the Kinetic Molecular Theory of GasesGases consist of tiny particles (atoms or molecules)These particles are so small, compared with the distances betweenthem, that the volume (size) of the individual particles can be assumedto be negligible (zero).3. The particles are in constant random motion, colliding with the walls ofthe container.? These collisions with the walls cause the pressure exertedby the gas.4. The particles are assumed not to attract or to repel each other.5. The average kinetic energy of the gas particles is directly proportionalto the Kelvin temperature of the gas
10 Kinetic Theory and the Gas Laws Dorin, Demmin, Gabel, Chemistry The Study of Matter ?, 3rd?Edition, 1990, page 323 (newer book)
11 A Gas Sample is Compressed Zumdahl, Zumdahl, DeCoste, World of Chemistry ?2002, page 429