Sublimation and Deposition

Active learning helps students grasp sublimation and deposition because these processes are invisible without concrete examples. Hands-on exploration with dry ice and cold surfaces makes abstract concepts visible, helping students build accurate mental models of phase changes that are otherwise hard to visualize.

• 5th Class
• Scientific Inquiry and the Natural World
• 4 activities
• 20 min–40 min

Learning Objectives

1. Explain the process of sublimation using dry ice as an example.
2. Analyze the conditions required for sublimation and deposition to occur.
3. Compare and contrast sublimation and deposition with melting and evaporation.
4. Identify real-world examples of sublimation and deposition.

Case Study Analysis

⏱ 25 min·Whole Class

Demonstration: Dry Ice Sublimation

Place small pieces of dry ice in a clear container with a warm cloth draped over it to trap fog. Students observe the solid disappearing into gas and measure mass loss over time. Discuss safety rules like gloves and ventilation first.

Prepare & details

Explain the process of sublimation using dry ice as an example.

Facilitation Tip: During the Dry Ice Sublimation demonstration, use a balance to show students that the mass decreases as the dry ice sublimes, reinforcing that gas has mass and leaving no liquid behind.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 30 min·Small Groups

Experiment: Frost Formation for Deposition

Chill metal cans in a freezer, then place them in humid air. Students watch water vapour deposit as frost, timing the process and noting conditions like temperature. Compare to regular freezing by touching ice cubes.

Prepare & details

Analyze the conditions under which sublimation and deposition occur.

Facilitation Tip: For the Frost Formation experiment, place a metal tray in the freezer overnight so students observe visible frost buildup, making deposition tangible.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 20 min·Pairs

Comparison Chart: Phase Changes

Provide diagrams of melting, evaporation, sublimation, and deposition. In pairs, students fill charts with examples, conditions, and particle sketches, then share one key difference with the class.

Prepare & details

Compare sublimation to melting and evaporation.

Facilitation Tip: When creating the Comparison Chart, have students include diagrams with arrows showing the direction of energy transfer for each phase change.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 40 min·Small Groups

Inquiry Stations: Sublimation Hunt

Set stations with mothballs, iodine crystals, and dry ice. Groups predict which sublimes, observe over 10 minutes, and rotate to record evidence. Conclude with a class vote on fastest sublimation.

Prepare & details

Explain the process of sublimation using dry ice as an example.

Facilitation Tip: At the Inquiry Stations, provide a simple checklist for students to record observations and predictions before rotating to the next example.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Teaching This Topic

Teach this topic through cycles of observation, prediction, and explanation. Start with surprising demonstrations, like dry ice disappearing without a puddle, to create cognitive conflict. Use small-group discussions to resolve observations into explanations, avoiding overemphasis on memorizing terms. Research shows students learn phase changes best when they connect energy transfer to molecular motion, so guide them to describe what happens to particles during each process.

What to Expect

Successful learning looks like students correctly identifying sublimation and deposition in real-world examples, distinguishing these processes from melting and freezing, and explaining the role of temperature and pressure. They should use accurate vocabulary when describing state changes and connect observations to scientific explanations.

Watch Out for These Misconceptions

Common Misconception

During the Demonstration: Dry Ice Sublimation, watch for students who assume a liquid must form. Redirect them by pointing to the balance and asking, 'Where is the liquid? What do you notice about the mass?'.

What to Teach Instead

In the Demonstration: Dry Ice Sublimation, students will see no liquid form and observe mass decrease. Prompt them to explain what happens to the dry ice particles and how this differs from melting.

Common Misconception

During the Experiment: Frost Formation for Deposition, watch for students who confuse frost with frozen water. Redirect by asking, 'Did the water freeze first? What do we see forming directly from the air?'.

What to Teach Instead

In the Experiment: Frost Formation for Deposition, students observe frost forming directly from water vapor. Have them compare this to ice forming from liquid water, focusing on the absence of the liquid phase.

Common Misconception

During the Inquiry Stations: Sublimation Hunt, watch for students who say only dry ice sublimes. Redirect by asking, 'What other solids in the room might sublime? How can we test that idea?'.

What to Teach Instead

In the Inquiry Stations: Sublimation Hunt, students test multiple examples like mothballs and snow. Encourage them to predict which will sublime faster and explain why, using observations from the stations.

Assessment Ideas

Quick Check

After the Demonstration: Dry Ice Sublimation, present images of dry ice and frost formation. Ask students to write one sentence for each image explaining which phase change is occurring and why, using the key term sublimation or deposition.

Discussion Prompt

During the Comparison Chart: Phase Changes activity, pose the question, 'How is sublimation different from evaporation, and how is deposition different from condensation?' Facilitate a class discussion where students use the key vocabulary to explain the differences, referring to their chart.

Exit Ticket

After the Experiment: Frost Formation for Deposition, ask students to draw a simple diagram showing either sublimation or deposition. They should label the states of matter involved and the direction of the phase change with arrows.

Extensions & Scaffolding

• Challenge students to research another substance that sublimes, such as iodine or camphor, and prepare a short explanation with evidence.
• Scaffolding: Provide a word bank with terms like energy, particles, solid, gas, temperature for students to use in labeling diagrams.
• Deeper exploration: Have students design a simple experiment to test how temperature affects sublimation rates using ice and salt mixtures.

Key Vocabulary

sublimation	The process where a solid changes directly into a gas without becoming a liquid first. Dry ice turning into carbon dioxide gas is a common example.
deposition	The process where a gas changes directly into a solid without becoming a liquid first. Frost forming on a cold window is an example.
phase change	A physical process that results in the transformation of a substance from one solid state to another. This includes melting, freezing, evaporation, condensation, sublimation, and deposition.
particle energy	The amount of kinetic energy that the tiny parts (particles) of a substance have. Higher energy means particles move more, affecting phase changes.