3.2.4
Latent Heat
Changes of State
Changes of State
Objects can change state from one state of matter to another. Melting and boiling are examples of changes of state.
Melting - solid to liquid
Melting - solid to liquid
- If we heat a solid, the solid particles vibrate more energetically, until they have enough energy to overcome the forces between them.
- This is when the solid melts (becomes a liquid).
- The temperature needed for this to happen is the melting point.
- Melting is sometimes also called fusion.
Boiling - liquid to gas
Boiling - liquid to gas
- If we heat a liquid, the liquid particles move more energetically until they have enough energy to escape completely from the forces between them.
- The particles become a gas and move completely freely.
- The temperature needed for this to happen is the boiling point. Boiling can be called vaporisation.
Condensation - gas to liquid
Condensation - gas to liquid
- When the temperature of a gas decreases to the boiling point, the strength of the forces between particles increases and the particles condense to become a liquid.
- For the same material, its boiling point is the same as its condensing point.
Solidifying (Freezing) - liquid to solid
Solidifying (Freezing) - liquid to solid
- When the temperature of a liquid decreases to the melting point, the strength of the forces between particles increases and the liquid solidifies to become a solid.
- For the same material, its melting point is the same as its freezing point.
Latent Heat
Latent Heat
Latent heat is the energy that is transferred to a substance without the substance's temperature changing. This happens when a substance is changing state.
Where does latent heat go?
Where does latent heat go?
- When a substance changes state, this energy is absorbed (used) to create or weaken bonds, rather than transfer kinetic energy to a substance’s particles.
Why isn't latent heat measured?
Why isn't latent heat measured?
- If we measure energy using the change in temperature, this energy transfer will not be measured.
- The energy is transferred without the temperature changing.
Specific latent heat
Specific latent heat
- Specific latent heat is the latent heat per 1kg of mass.
- It is a way to standardise across objects that have different masses.
Latent heat's other names
Latent heat's other names
- When a solid becomes a liquid or a liquid becomes a solid, this hidden energy is called the latent heat of fusion.
- When a gas becomes a liquid, or a liquid becomes a gas, this hidden energy is called the latent heat of vaporisation.
The Latent Heat of Vapourisation
The Latent Heat of Vapourisation
The latent heat of vapourisation is the amount of energy needed to convert a liquid into a gas (or a gas into a liquid) without changing the substance's temperature.
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
Jump to other topics
1Energy
1.1Energy Changes
1.1.1Energy Stores
1.1.2Calculating Changes in Energy
1.1.3Changes in Kinetic Energy - Calculations
1.1.4Changes in GPE - Calculations
1.1.5Changes in EPE - Calculations
1.1.6Energy Transfers
1.1.7Mechanical Work Done
1.1.8Mechanical Work - Calculations
1.1.9Electrical Work Done
1.1.10Electrical Work Done- Calculations
1.2Energy Losses & Efficiency
2Electricity
2.1Electric Charge
2.2Resistance & Electrical Work
2.3Electric Circuits
2.4Electricity in Homes
2.5Static Electricity
3Particle Model of Matter
3.1States of Matter
3.2Heat
4Atoms & Radiation
4.1Atoms
4.2Radiation
4.2.1Radioactive Decay
4.2.2Radioactive Decay 2
4.2.3Types of Radioactive Emission
4.2.4Fission & Fusion
4.2.5Radioactive Decay Equations
4.2.6Radio. decay equations - Calculations
4.2.7Half Lives & Ionising Radiation
4.2.8Half Life - Calculations
4.2.9Uses & Dangers of Radiation
4.2.10Uses & Dangers of Radiation 2
4.2.11End of Topic Test - Atoms & Radiation
4.2.12Grade 9 - Radiation
4.2.13Exam-Style Questions - Radioactive Decay
5Forces
5.1Basics of Motion
5.2Forces
5.2.1Gravity
5.2.2Gravity - Calculations
5.2.3Resultant Forces
5.2.4Newton Second Law - Calculations
5.2.5Force Diagrams
5.2.6Free Body Diagrams - Calculations
5.2.7Stretching a Spring
5.2.8Hooke's Law
5.2.9Hooke's Law - Calculations
5.2.10Elastic Potential Energy
5.2.11Elastic Potential - Calculations
5.2.12Exam-Style Questions - Elastic Potential Energy
5.3Effects of Forces
6Waves
6.1Wave Basics
6.2Waves at a Boundary
6.3Sound Waves
6.4Electromagnetic Waves
7Magnetism
7.1Magnetism Basics
7.2Electromagnetism
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