freezing/boiling point graphs & calculations

Views:
 
Category: Education
     
 

Presentation Description

Interpreting Freezing/Boiling Point Graphs and completing Enthalpy calculations

Comments

Presentation Transcript

Temperature & Phase Changes:

Temperature & Phase Changes As heat is added to a solid, liquid, or gas, the temperature increases Kinetic Energy is increasing When the phase is changing, there is no change in temperature Potential Energy is increasing (particles are rearranging) Energy is necessary to overcome the intermolecular forces (IMF) in order for substance to transition states

Freezing & Boiling Point Graph (H2O):

Freezing & Boiling Point Graph (H 2 O) Energy  Temperature ( °C) -15 0 100 120 Ice (solid) S L Melting Point Water (liquid) L G Steam (gas) Boiling Point

Please pause the Presentation and Complete the Freezing And Boiling Point Graph Worksheet:

Please pause the Presentation and Complete the Freezing And Boiling Point Graph Worksheet

Enthalpies of Fusion & Vaporization:

Enthalpies of Fusion & Vaporization Energy needed to melt 1 g of a substance at its melting point is called the enthalpy of fusion ( D H fus ) Water’s D H fus = 334 J/g Energy needed to boil 1 g of a substance at its boiling point is called the enthalpy of vaporization ( D H vap ) Water’s D H vap = 2260 J/g

Solving Enthalpy of Fusion/Vaporization Problems:

Solving Enthalpy of Fusion/Vaporization Problems Sketch a diagram of the changes the substance will be undergoing Setup a problem for each stage (heating a phase or phase change) Heat added/lost within a single phase  q = m D TC p Heat added/lost at a phase change q = m D H fus/vap Add the heats for each stage to determine your final answer C p(water) = 4.184 J/g C | C p(ice) = 2.06 J/g C | C p(steam) = 2.02 J/g C