Change Of State
Aperçu
Heat a block of ice steadily and something remarkable happens: the temperature rises, pauses, rises again, pauses once more, then climbs a third time. Those pauses mark the moments when the substance is changing state, and understanding why the thermometer stalls is the key to unlocking this entire topic.
This lesson takes you through the particle model of solids, liquids and gases, explains every change of state, introduces specific heat capacity and the equation that links energy to temperature change, and shows you how to read and interpret heating curves. These ideas appear regularly across both Edexcel Papers 1 and 2.
Objectifs
- Explain why heating a system will change the energy stored within the system and raise its temperature or produce changes of state
- Describe the changes that occur when a solid melts to form a liquid, and when a liquid evaporates or boils to form a gas
- Describe the arrangement and motion of particles in solids, liquids and gases
- Obtain a temperature-time graph to show the constant temperature during a change of state
- Know that specific heat capacity is the energy required to change the temperature of an object by one degree Celsius per kilogram of mass
- Use the equation: change in thermal energy = mass x specific heat capacity x change in temperature
- Investigate the specific heat capacity of materials including water and some solids
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Note de cours
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Évaluation de la leçon
Félicitations, vous avez terminé la leçon sur Change Of State. Maintenant que vous avez exploré le concepts et idées clés, il est temps de mettre vos connaissances à l'épreuve. Cette section propose une variété de pratiques des questions conçues pour renforcer votre compréhension et vous aider à évaluer votre compréhension de la matière.
Vous rencontrerez un mélange de types de questions, y compris des questions à choix multiple, des questions à réponse courte et des questions de rédaction. Chaque question est soigneusement conçue pour évaluer différents aspects de vos connaissances et de vos compétences en pensée critique.
Utilisez cette section d'évaluation comme une occasion de renforcer votre compréhension du sujet et d'identifier les domaines où vous pourriez avoir besoin d'étudier davantage. Ne soyez pas découragé par les défis que vous rencontrez ; considérez-les plutôt comme des opportunités de croissance et d'amélioration.
- Which statement correctly describes the particles in a liquid? A) They vibrate about fixed positions B) They are far apart and move randomly C) They are close together and can slide past each other D) They are arranged in a regular pattern Answer: C
- During boiling, the temperature of a pure substance: A) Increases steadily B) Decreases steadily C) Stays constant D) Fluctuates up and down Answer: C
- What is the specific heat capacity of a substance? A) The energy needed to melt 1 kg of the substance B) The energy needed to raise 1 kg by 1 degree Celsius C) The temperature at which the substance changes state D) The energy stored in the bonds of the substance Answer: B
- A flat section on a heating curve indicates that: A) The heater has been switched off B) The substance has reached its maximum temperature C) A change of state is occurring D) The substance is cooling down Answer: C
- Which process is the reverse of melting? A) Boiling B) Evaporation C) Condensation D) Freezing Answer: D
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Livres recommandés
Pour aller plus loin, ressources libres
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Section de manuel
Phase Change and Latent Heat
Explain changes in heat during changes of state, and describe latent heats of fusion and vaporization
"Physics: Phase Change and Latent Heat" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/11-3-phase-change-and-latent-heat. Access for free at https://openstax.org/books/physics/pages/1-introduction
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Section de manuel
Temperature Change and Heat Capacity
One of the major effects of heat transfer is temperature change: heating increases the temperature while cooling decreases it. We assume that there is no phase change and that no work is done on or by the system. Experiments show that the transferred heat depends on three factors—the change in tempe
"College Physics: Temperature Change and Heat Capacity" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/14-2-temperature-change-and-heat-capacity. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Publiées par d'autres organisations sous licence libre, créditées comme elles le demandent. Les liens ouvrent leurs sites.
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