Talent Unlimited High School, Manhattan
Summer Research Program for Science Teachers
Unit: The Physical Behavior of Matter
Topics: Vapor pressure of different substances and how they relate to intermolecular forces.
Aim: What is vapor pressure and how is it related to intermolecular forces?
Do Now: Complete 1- 3. Write in complete sentences.
1) How is boiling point related to the strength of an intermolecular force?
2) Rank the following substances in order of increasing melting point.
H2(g) CaCl2(aq) H2O(l)
3) What will happen if a glass of water is left uncovered at room temperature, for several weeks?
Procedure of Lesson:
Students are instructed how vapor pressure relates to intermolecular forces (something they should already have been exposed to). The way this can be done is to use pictures to explain the interactions occurring in 1) hydrogen bonds 2) dispersion forces 3) molecule ion interactions.
a. Arrange the substances in order of evaporation, from fastest to slowest evaporation.
b. Using your answer to question #1 above, arrange the substances in order of strongest to weakest intermolecular forces.
c. Using your answer to #3 above, arrange the substances in order of increasing boiling point.
d. Arrange the substances in order of decreasing melting point.
e. What is the relationship between intermolecular force strength and vapor pressure?
9. Students are instructed how to read a vapor pressure chart.
Summary: Students must answer the following questions.
1. Identify the type of intermolecular force in each substance (you can abbreviate):
HF(g) _____ NaF(aq) _____ F2(g) _____ H2(l)_____
2. Arrange the following substance in order of decreasing boiling point: 1= lowest 4=highest
H2O(l) _____ Xe(g) _____ Ne(g) _____ CaCl2(aq) _____
3. Draw the molecule ion attraction between H2O and Na+
Homework: Complete the worksheet.
Content Standard A:
As a result of activities in grades 9-12, all students should develop
1) Understandings about scientific inquiry
Content Standard B:
As a result of their activities in grades 9-12, all students should develop an understanding of
1) Structure of atoms
2) Structure and properties of matter
3) Interactions of energy and matter