Journal Entry:

If you are given a mass and a balanced equation how do you determine enthalpy?

If you are given a mass and two temperatures, how do you determine enthalpy?

Learning Intentions

• We will learn how to analyze how energy is transferred to a system to cause a substance to melt or boil, but the temperature remains constant during a phase change.

• We will learn the energy absorbed during a phase change is equal to the energy released in a complementary phase change in the opposite direction.

• We will learn how to calculate enthalpy of heating or cooling processes and what constants to use in different stages of the process.

Closing Task:

You can determine what happens to the energy added during each stage of a heating/cooling curve

You can set up the appropriate equations to solve for enthalpy of phase changes.

Content Standards being covered:

Chemical system undergo three main processes that change their energy: heating/cooling, phase transitions, and chemical reactions. (E.K. 5.B.3.)

At the particulate scale, chemical processes can be distinguished from physical processes because chemical bonds can be distinguished from intermolecular interactions. (E.K. 5.D.2)

 Explain changes in the heat (q) absorbed or relased by a system undergoing a phase transition based on the amount of th esubstance in moles ande the molar enthalpy of the phase transtiion. (ENE-2.E)