Phase DiagramFEBRUARY 11, 2015

SCIENCE STARTER

• DO THE SCIENCE STARTER• TAKE 3 MINUTES• YOU ARE SEATED AND

SILENT• ALSO TAKE OUT YOUR

JOURNAL

Upcoming assessment

•First assessment this Friday.

AIM•Explain, in term of heat of fusion and

heat of vaporization, which interval (interval DE or interval BC) has a larger amount of heat added.

VOCABULARY

• Triple point• Heat of fusion• Heat of vaporization

phase

•Phase depends upon chemical structure and state of matter (solid, liquid, gas)

•A substance in the same PHASE has the same CHEMICAL composition and properties

phase•Temperature and pressure determine the phase

Phase Diagram

Phase diagram•3 regions•Substance in each region can not change into a different phase

•Lines represent the pressure and temperature at which phase transition can occur in equilibrium

•Critical point – the point at which the liquid and gas phases are indistinguishable

Triple Point• the temperature and pressure at

which the solid, liquid, and vapor phases of a pure substance can coexist in equilibrium.

Heat energy•Amount of heat energy needed to change the temperature of a system of mass between two temperature

•q=mCΔT q = heat energy (J) m = mass of the substance (g) C = specific heat capacity (J/g K) ΔT = change in temperature of the substance

Heat of fusion•Heat energy needed to change 1 g of a substance from solid to liquid▫q=mHf

q = heat energy required for a phase change (J)

m = mass of the substance (g) Hf = heat of fusion (J/g)

Heat of vaporization•Heat energy needed to change 1 g of a substance from liquid to a gas▫q=mHv

q = heat energy required for a phase change (J)

m = mass of the substance (g) Hv = heat of vaporization (J/g)

Heat energy examples•What is the amount of heat energy released when 50.0 grams of water is cooled from 20.0˚C to 10.0˚C (Jan 2014 Regent)?

Heat of fusion example

•What is the total amount of heat required to liquefied 1.00 gram of H20 (s) at 0.˚C and 1 atm (atmosphere)?

Heat of vaporization example

•What is the total amount of heat required to vaporize 1.00 gram of H20 (l) at 100.˚C and 1 atm (atmosphere)?

AIM PROMPT•Explain, in term of heat of fusion and

heat of vaporization, which interval (interval DE or interval BC) has a larger amount of heat added.

• Use the RACE format (A paragraph of at least 3 sentences). Use evidence from class discussion and notes.