Key Idea.
Section 1
The Energy Threshold
Phase changes are not instant. Because molecular attraction is always pulling, molecules need a specific amount of energy to break free.
They must build up enough kinetic energy to reach a "tipping point." Until this threshold is crossed, the attraction holds strong, and the substance remains in its current phase.
Section 2
Overcoming the Pull
On Titan, the methane lake didn't vanish the moment the sun came out. The molecules had to absorb energy over time.
Only when their speed became sufficient to overcome the specific strength of methane's molecular attraction could they escape as gas. This explains the delay between the start of summer and the lake's disappearance.
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Section 1
The Energy Threshold
Phase changes are not instant. Because molecular attraction is always pulling, molecules need a specific amount of energy to break free.
They must build up enough kinetic energy to reach a "tipping point." Until this threshold is crossed, the attraction holds strong, and the substance remains in its current phase.
Section 2
Overcoming the Pull
On Titan, the methane lake didn't vanish the moment the sun came out. The molecules had to absorb energy over time.
Only when their speed became sufficient to overcome the specific strength of methane's molecular attraction could they escape as gas. This explains the delay between the start of summer and the lake's disappearance.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter