Thermodynamics & Energy · GCSE Physics Topic 3
Phase Change Melting & Boiling Curve Simulator
Key exam takeaway: Both crystalline melting and liquid boiling absorb latent heat at constant temperature. Higher altitude lowers atmospheric pressure, reducing water's boiling point below 100°C.
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3D Simulation Stage● 60 FPS
Parameter Controls
W
kPa
g
Live Derivations & Metrics
Melting Point
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Boiling Point
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Current Phase State
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Latent Heat Phase
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Real-Time Formula Derivation
Governing Formula:
--Substitution:
--Regime: --
Worked Examples & Exam Question Deep Dive
Worked Problem
Problem: Water temperature plateau holds at 98°C. What is boiling point? Is atmospheric pressure above or below 1 atm?
Step-by-Step Derivation:
- Boiling point is 98°C. Below 1 atm because standard boiling point is 100°C (lower pressure lowers boiling point).
Worked Problem
Problem: Does a 0°C ice cube melt in a perfectly insulated 0°C room? Why?
Step-by-Step Derivation:
- No! Melting requires reaching melting point AND continuing to absorb heat. Zero temperature difference means zero heat transfer.
Student Inquiry Worksheet & Practice Problems
Q1. Variant 1: Why use a water bath rather than direct flame heating in solid melting experiments?
Answer Key: Ensures uniform heating across the entire sample tube and slows the temperature rise rate for accurate observations.
Q2. Variant 2: How do bubble sizes change as they ascend before vs during boiling?
Answer Key: Before boiling: bubbles shrink as water vapor re-condenses in cooler top layers. During boiling: bubbles grow as hydrostatic pressure decreases.
Q3. Variant 3: How does a pressure cooker cook beef rapidly using the pressure-boiling point relationship?
Answer Key: Trapped steam raises internal pressure to ~2 atm, boosting water boiling point to ~120°C, speeding chemical tenderization.
Frequently Asked Questions & Misconceptions
What physics explains the proverb "It is not cold when snowing, but freezing when snow melts"?
Snow formation is an exothermic release of latent heat. Snow melting absorbs immense latent heat from surrounding air, plunging ambient temperatures.
Why does a 100°C steam scald inflict far more severe tissue burn than 100°C boiling water?
Steam must first condense into boiling water, releasing massive latent heat of vaporization (2260 kJ/kg) before cooling, delivering double heat.
Is the thick white fog billowing around sublimating dry ice gaseous carbon dioxide?
No! CO2 gas is transparent and invisible. The dense fog consists of microscopic liquid water droplets condensed from humid air chilled by dry ice.
Why can a paper pot boil water over an open flame without catching fire?
Paper's ignition point is ~180°C. Boiling water absorbs heat at 100°C plateau, chilling the paper below ignition threshold.