Lesson Plan
Lesson: Colligative Properties of Solutions
Aim :
To study the colligative properties of solutions.
Learning Outcomes :
By the end of the lesson, students will be able to explain qualitatively the effect of a non-
volatile solute on the vapour pressure of a solvent, and hence on its melting and boiling
points.
Assumed prior knowledge :
Students should already be familiar with :
1. the phase diagram of water.
2. the concept of freezing point and boiling point of a substance.
Underlying Principles
1. Making the invisible, visible.
2. Enabling students to know what to look for.
Time taken to complete the activities : 80 minutes
Differentiation
Questions in the student notes are designed to enable all students to complete the activity.
The pop-up answers are provided for the students to view when they have considered their
responses. Worksheet questions include questions that require recall, understanding and
application of the new concepts learned.
© 2003 Ministry of Education Malaysia. All Rights Reserved. Page 1 of 3
Development of Lesson :
No. Steps Strategy Resources
1 Set Induction. • Teacher to quiz students to ensure that
(Ascertaining prior they have the necessary background
knowledge and knowledge.
introducing lesson
topic for the day). • Teacher to point out lesson objectives for
the day.
2 Student Activity Teacher to go through Activities 1 - 2 • Courseware
with the students.
• Activity 1 : Colligative properties
Students are shown how the vapour
pressure, boiling point and freezing point
of water are affected by the addition of an
non-volatile solute such as NaCl.
• Activity 2 : Colligative properties –
molecular view
Students are shown why the presence of
a non-volatile solute causes an increase
in the boiling point and a decrease in the
freezing point of water.
3 Evaluation • Students to answer questions in the • Worksheet
student worksheet on their own.
4 Extension activity • Students to go through the extension • Websites
activities on their own. • Reference
books.
© 2003 Ministry of Education Malaysia. All Rights Reserved. Page 2 of 3
Worksheet answers
1. Colligative properties
1.1 B
1.2 a. Mr of C6H12O6 = 6(12.0) + 12(1.0) + 6(16.0) = 180
700
Number of moles of C6H12O6 = = 3.889
180
Increase in boiling point = 3.889 x 0.51 = 1.983
Boiling point of solution = 100 + 1.983 = 101.983 = 101 °C.
500.0
b. Number of moles of C6H12O6 = = 2.778
180
2.778 x 1000 x 0.51
Increase in boiling point = = 1.889 °C.
750
Boiling point of solution = 100 + 1.889 °C = 101.889 = 102 °C.
Boiling point of solution = 100 + 0.816 = 100.816 = 101 °C.
1.3 Mr of C2H6O2 = 2(12.0) + 6(1.0) + 2(16.0) = 62
22.5
Number of moles of C2H6O2 = = 0.363
62.0
Decrease in freezing point = 0.3629 x 1.86 = 0.6750 °C.
Freezing point of solution = 0 - 0.6750 = -0.675 °C.
© 2003 Ministry of Education Malaysia. All Rights Reserved. Page 3 of 3
