SCH3U Chemistry Grade 11 University Preparation

Unit F - Gases and Atmospheric Chemistry:Lesson 3

Date: December 2, 2011

Gas Laws 1 (Boyle’s Law and Charles’ Law)

Lesson Outline

Strategies / Rationale / Assessment / Materials Required
Time: 10min / Before: Minds On / Teacher demonstrates Boyle’s Law with vacuum pump or Cartesian diver demo (Appendix 2).
Teacher demonstrates Charles’ Law with liquid nitrogen balloon demo (Appendix 3) / Demos are used to get students excited about the material discussed in this lesson.
The students are encouraged (by not being given explanations of what is going on) to question these results and create hypotheses to explain their observations (inquiry based learning) / Assessment as learning – students are forced to consider what they already know and try to apply it to new material.
Teacher has students record hypotheses to compare to later ideas (Appendix 4) / 1 large rubber balloon
1 vacuum pump
Glass vacuum chamber
OR
1 2L clear plastic bottle
1 clear glass eyedropper
5mL food dye solution
AND
1 large rubber balloon
Large transparent plastic container (optional)
1 large dewar filled with liquid nitrogen
Cryogenic gloves
Tongs
Time: 50min / During: Action / Class is split in two. One half completes the Boyle’s Law hands-on investigation (Appendix 5) and the Boyle’s Law worksheet (Appendix 6) in small groups (2-3) Second half completes the Charles’ Law investigation (Appendix 7) and the Charles’ Law worksheet (Appendix 8) in small groups (2-3)
Halfway through, the two groups switch so all students complete both sections.
Finally, class comes back together to discuss the two laws and explain the earlier demos. Discussion leads to a quantification of the relationships between the properties. / These investigations will allow the students to directly engage with the material and come to their own conclusions about these laws based on real information. The students are given the opportunity to investigate these physical relationships and come to their own conclusions (Inquiry-based learning)
Class discussion ensures that any misconceptions are cleared up, ensuring that every student has a fundamental understanding of the material. / Hands-on Investigations:
Data sheets can be assessed (by teacher survey or peer assessment) to ensure student understanding (Assessment for learning)
Worksheets:
Student graphs and expressions of the relationships between the properties can be taken in and assessed by the teacher for application of the laws (Assessment for learning) / Required for Each Group:
1 Plastic syringe
1 Air-tight cap for syringe
2 Marshmallows
1 set of cylindrical masses (various masses)
AND
2 small balloons (inflated)
Large ice bath
Ruler
Hot plate
Length of string
Pre-warmed large water bath
2 Thermometers
1 sheet of Graph Paper
All worksheets

SCH3U Chemistry Grade 11 University Preparation

Unit F - Gases and Atmospheric Chemistry:Lesson 3

/
Date: December 2, 2011

Gas Laws 1 (Boyle’s Law and Charles’ Law)

Learning Goals: For students to understand the qualitative relationship between Pressure and Volume (as one increases, the other decreases), and between Volume and Temperature (as one increases, the other increases)
Big Ideas: Properties of gases can be described qualitatively and quantitatively, and can be predicted
Relevant Ministry Expectations: F2.1, F2.2, F2.3, F3.4, F3.5, A1.1, A1.2, A1.5, A1.6, A1.8, A1.10, A1.12 (See Appendix 1)
Prior Knowledge: From previous courses: The nature of scientific measurement and data collection; the concept of forces; the nature of gases – higher energy state of matter, expands to fill its container
From previous lessons in this unit: The nature of the important gas properties (temperature, pressure, volume); the concept of a force as related to pressure
Strategies / Rationale / Assessment / Materials Required
Time: 10min / After: Consolidation & Connection / Two conceptual questions are posed to the class, covering the two laws:
- Using what we have learned today, can you explain why a weather balloon is not filled completely when it is launched?
- Using what we have learned today, can you explain how a hot-air balloon works?
The students are assigned one question and asked to complete a think-pair-share to share their ideas with the class and convince themselves/their partners/their classmates of their interpretation of the scenario. / This allows the teacher to assess higher order thinking skills relevant to the current topic. The students are forced to apply their understanding of the day’s lesson to more conceptual, higher-order questions. The students are given an opportunity to demonstrate their mastery of these topics by explaining these applications of the concepts to themselves, each other, and back to the teacher/class as a whole / Student discussion and class discussions can be used to allow the teacher to assess the class as a whole, and the students to self-assess their higher order comprehension of these Gas laws. (Assessment for learning, Assessment as learning)
As well, a stoplight exit card strategy can be employed (Green – OK, Yellow – some issues, Red – Do not understand) to allow the students the opportunity to self-reflect on their learning and communicate this information quickly and effectively to the teacher / None
Time: 1min / Next Steps / Homework is assigned in the form of a short worksheet encompassing conceptual Boyle’s and Charles’ law problems (Appendix 9) / Homework assignment is used to assess student understanding of the concepts discussed in the preceding lesson / Student responses on the homework assignment can be used to assess student comprehension of the laws as well as application of the concepts (Assessment for learning) / Worksheet

Note: Teacher Notes attached in Appendix 10

Appendix 1

Specific Ministry Expectations addressed in this lesson:

Unit F: Gases and Atmospheric Chemistry

Developing Skills of Investigation

and Communication

F2.1 use appropriate terminology related to gases

and atmospheric chemistry, including, but not

limited to: standard temperature, standard pressure,

molar volume, and ideal gas [C]

F2.2 determine, through inquiry, the quantitative

and graphical relationships between the pressure,

volume, and temperature of a gas [PR, AI]

Chemistry

F2.3 solve quantitative problems by performing

calculations based on Boyle’s law, Charles’s

law, Gay-Lussac’s law, the combined gas law,

Dalton’s law of partial pressures, and the ideal

gas law [AI]

Understanding Basic Concepts

F3. Understanding Basic Concepts

F3.4 describe, for an ideal gas, the quantitative

relationships that exist between the variables of

pressure, volume, temperature, and amount

of substance

F3.5 explain Dalton’s law of partial pressures,

Boyle’s law, Charles’s law, Gay-Lussac’s law,

the combined gas law, and the ideal gas law

Unit A: Scientific Investigation Skills

A1.1 formulate relevant scientific questions about

observed relationships, ideas, problems, or

issues, make informed predictions, and/or

formulate educated hypotheses to focus inquiries

or research

A1.2 select appropriate instruments (e.g., a balance,

glassware, titration instruments) and materials

(e.g., molecular model kits, solutions), and

identify appropriate methods, techniques, and

procedures, for each inquiry

A1.5 conduct inquiries, controlling relevant

variables, adapting or extending procedures as

required, and using appropriate materials and

equipment safely, accurately, and effectively, to

collect observations and data

A1.6 compile accurate data from laboratory and

other sources, and organize and record the data,

using appropriate formats, including tables, flow

charts, graphs, and/or diagrams

A1.8 synthesize, analyse, interpret, and evaluate

qualitative and quantitative data; solve problems

involving quantitative data; determine

whether the evidence supports or refutes the

initial prediction or hypothesis and whether it is

consistent with scientific theory; identify sources

of bias and error; and suggest improvements

to the inquiry to reduce the likelihood of error

A1.10 draw conclusions based on inquiry results

and research findings, and justify their conclusions

with reference to scientific knowledge

A1.12 use appropriate numeric, symbolic, and

graphic modes of representation, and appropriate

units of measurement (e.g., SI and imperial units)

A2. Career Exploration

Appendix 2

Boyle’s Law Demonstration

Teacher Demonstration

Note: use Option 1 if a vacuum pump is available, if not use Option 2

Option 1:

Materials:

1 large inflated rubber balloon

1 vacuum pump

Glass vacuum chamber

Demonstration:

1. Teacher holds up inflated rubber balloon for whole class to see

2. Place balloon in glass vacuum chamber

3. Attach vacuum pump and evacuate the vacuum chamber, until the volume of the balloon noticeably shrinks

4. Turn off the vacuum and vent the chamber. Allow balloon to re-expand, as the pressure surrounding it returns to atmospheric temperature.

Safety Concerns:

Ensure familiarity with how to use vacuum pump, how to evacuate chamber and to vent the vacuum correctly. Eye protection should be worn by teacher, and students kept a reasonable distance away from the demonstration.

Option 2:

Materials:

1 2L clear plastic bottle, filled with water

1 clear glass eyedropper

5mL brightly coloured food dye solution

Demonstration:

1. Teacher sucks up a small volume of coloured dye into the eye dropper, leaving enough air in the dropper to be visible to the students and to ensure the dropper floats partway down the bottle

2. Place dropper into bottle and hold bottle up to class so students can see the dropper floating and can see the air bubble trapped inside the dropper

3. Put the lid on the bottle, ensuring that the water fills the bottle completely

4. Compress the sides of the bottle, until the dropper starts to sink and the volume of gas trapped in the dropper shrinks

5. Release the sides of the bottle to allow the dropper to rise again, and eject a puff of dye solution as the gas rapidly expands

Safety Concerns:

None
Appendix 3

Charles’ Law Demonstration

Teacher Demonstration

Materials:

1 large inflated rubber balloon

Large transparent plastic container (optional – to contain splash from the liquid nitrogen)

1 large dewar filled with liquid nitrogen

Cryogenic gloves Before After

Tongs

Demonstration:

1. Teacher holds up inflated rubber balloon for whole class to see

2. Place balloon in transparent plastic container (if available). Ideally, the balloon should abut the sides of the container, so that it is suspended above the base.

3. Carefully pour liquid nitrogen over the balloon, until the volume of the balloon noticeably shrinks. Allow liquid nitrogen to evaporate.

4. Allow balloon to re-expand, as the air inside it returns to room temperature.

Safety Concerns:

Liquid nitrogen is extremely cold (-196°C) and will cause severe frostbite burns if poured onto exposed skin. Always use proper eye protection and wear cold-temperature insulated gloves (NOT winter gloves or latex gloves or oven mitts) when handling liquid nitrogen. Ensure students remain a safe distance away from the dewar of liquid nitrogen. Upon completion of the class, the liquid Nitrogen can be disposed of by pouring onto the floor/ground in small amounts at a time (it will evaporate instantly).

Appendix 4

Vacuum Chamber/Cartesian Diver

Describe your observations:
______
______

______

Propose a hypothesis or theory to explain what you observed:

______

Frozen Balloon

Describe your observations:
______
______

______

Propose a hypothesis or theory to explain what you observed:

______

Appendix 5

Boyle’s Law Investigation

Student Investigation (groups of 2-3):

Materials (per group of students):

1 Plastic syringe 1 Air-tight cap for syringe

2 Marshmallows 1 set of cylindrical masses (various masses)

Instructions:

Part A

1. Remove the plunger of the syringe and insert one marshmallow

2. Replace the plunger and push down until just touching the marshmallow.

3. Place the cap on the end of the syringe

4. Pull back on the plunger. Observe what happens to the marshmallow.

5. Release plunger. Observe what happens to the marshmallow.

6. Discuss with group. Compare the marshmallow in the syringe to the control marshmallow

Part B

1. Disassemble the syringe from Part A and remove the marshmallow

2. Reassemble the syringe/plunger/cap and record the volume of air contained in the syringe

3. Hold the syringe vertically, plunger-side up

4. Carefully place a cylindrical mass on top of the plunger

5. Record the mass of the cylindrical mass and the volume of air in the syringe in the table below

6. Repeat steps 5-6 with a variety of masses

7. Note any relationship between the two variables

Reading / Volume of air (mL) / Mass applied
(g) / Comments
1
2
3
4
5

Safety Notes:

Do not eat the marshmallows as we do not eat anything inside a science lab.

Appendix 5 ctd

Boyle’s Law Investigation Sample Completed

Student Investigation (groups of 2-3):

Materials (per group of students):

1 Plastic syringe 1 Air-tight cap for syringe

2 Marshmallows 1 set of cylindrical masses (various masses)

Instructions:

Part A

7. Remove the plunger of the syringe and insert one marshmallow

8. Replace the plunger and push down until just touching the marshmallow.

9. Place the cap on the end of the syringe

10. Pull back on the plunger. Observe what happens to the marshmallow.

11. Release plunger. Observe what happens to the marshmallow.

12. Discuss with group. Compare the marshmallow in the syringe to the control marshmallow

Part B

8. Disassemble the syringe from Part A and remove the marshmallow

9. Reassemble the syringe/plunger/cap and record the volume of air contained in the syringe