Changes in State

Changes in Stateo Vapor Pressure

▫ observation▫ definition▫ temperature dependence

o Changes in State▫ enthalpies▫ heating curves

o Phase Diagrams▫ special points ▫ examples

CTR

HP vapvap

1)ln(

Vapor Pressureo Dfns.

▫ pres. of vapor present above a (l) or (s)

▫ Hvap energy to convert 1 mole liquid to gas at 1 atm

o Eq. Vapor Pressure▫ rate of evaporation =

rate of condensationo Measuring Pvapor

▫ Hg columnPvapor = Patm – PHg column

Temperature Dependence

Temperature Dependence

CTR

HP vapvap

1)ln(

R = 8.3145 J/mol•KT = temperature (K)C = const. related to S

Changes in State: Heating Curve

Changes in State: Heating Curve

condensation

evaporation

Changes in State: Heating Curve

condensation

evaporation

melting

freezing

Changes in State: Heating Curve

condensation

evaporation

melting

freezing enthalpy of vaporization

Changes in State: Heating Curve

condensation

evaporation

melting

freezing enthalpy of vaporization

enthalpy of fusion

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)

1

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm▫ 2: T at P = 0.01 atm

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)

2

1

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm▫ 2: T at P = 0.01 atm▫ 3: T at P = 0.118 atm

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)32

1

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm▫ 2: T at P = 0.01 atm▫ 3: T at P = 0.118 atm▫ 4: T at P = 1 atm

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)32

1

4

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm▫ 2: T at P = 0.01 atm▫ 3: T at P = 0.118 atm▫ 4: T at P = 1 atm▫ 5: P at T = 100. C

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)32

1

4

5

Phase Diagramso Represents the

phases of a material at various T and P in a closed system

o Experiments▫ 1: T at P = 1 atm▫ 2: T at P = 0.01 atm▫ 3: T at P = 0.118 atm▫ 4: T at P = 1 atm▫ 5: P at T = 100. C▫ 6: P at T = 150. C

http://cwx.prenhall.com/petrucci/medialib/media_portfolio/text_images/FG13_18.JPG

Iodine

(546 C)

(0.118 atm)32

1

4

5 6

Phase Diagrams: Water

Phase Diagrams: Water