Year 7 Science · Unit 2 · Lesson 2
Challenge Worksheet
Learning Goals
Explain it to a Year 5 student
Imagine your younger cousin has never heard of sublimation. Use the sentence starters below to explain it clearly. You can use real examples from everyday life. Write 2–3 sentences for each starter.
"The basic idea of sublimation is…"
"A good example from everyday life is…" (Hint: think about dry ice, or how snow disappears on cold sunny days without puddles forming.)
"The reason sublimation is different from melting is…" (Think about what state it skips.)
"One thing people often get confused about is…"
1. Dry ice is solid carbon dioxide (CO₂) at −78.5°C. When left at room temperature (about 22°C), it turns into a cloud of gas without ever becoming a liquid. Using particle theory, explain why the solid particles can go directly to gas without passing through a liquid stage. Refer to the forces between particles in your answer.
2. Snow in the Snowy Mountains sometimes disappears on cold, sunny winter days without forming puddles — scientists call this "snow sublimation." A news article claims "the snow just evaporates like water." Is this accurate? Explain the scientific difference between evaporation and sublimation, and state which process is actually occurring with snow.
Wrap Up
In one sentence, what was the main idea of this lesson?