3.1.5

Changes of State

Test yourself

Changes of State

Changes of state are physical changes.

Illustrative background for Physical (not chemical) changeIllustrative background for Physical (not chemical) change ?? "content

Physical (not chemical) change

  • When a material changes state, it is able to recover its old properties if the change is reversed.
  • Some chemical reactions are also reversible.
  • However, some chemical reactions are irreversible.
    • In irreversible chemical reactions, the material would not be able to return to its original properties.
Illustrative background for Conservation of massIllustrative background for Conservation of mass ?? "content

Conservation of mass

  • When a substance changes state, its mass is conserved (stays the same).

Changes of State

Objects can change state from one state of matter to another. Melting and boiling are examples of changes of state.

Illustrative background for Melting - solid to liquidIllustrative background for Melting - solid to liquid ?? "content

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.
Illustrative background for Boiling - liquid to gasIllustrative background for Boiling - liquid to gas ?? "content

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.
Illustrative background for Condensation - gas to liquidIllustrative background for Condensation - gas to liquid ?? "content

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.
Illustrative background for Solidifying (Freezing) - liquid to solidIllustrative background for Solidifying (Freezing) - liquid to solid ?? "content

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.

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

1.2.1Energy Losses & Efficiency

1.2.2Energy Losses & Efficiency 2

1.2.3Efficiency - Calculations

1.2.4Grade 9 - Energy & Efficiency

1.3Energy Resources

1.3.1Fossil Fuels & Geothermal Energy

1.3.2Wind & Water Energy Sources

1.3.3Nuclear & Solar Energy

1.3.4Sustainability

1.3.5Renewable Energy

1.3.6End of Topic Test - Energy

1.3.7Exam-Style Questions - Energy

2Electricity

2.1Electric Charge

2.1.1Circuit Diagrams & Components

2.1.2Current

2.1.3Current - Calculations

2.1.4Conductors

2.1.5Potential Difference

2.1.6Voltage - Calculations

2.2Resistance & Electrical Work

2.2.1Resistance

2.2.2Diodes, LDRs & Thermistors

2.2.3Electrical Work

2.2.4Ohm's Law

2.2.5Resistance and Ohms Law - Calculations

2.2.6Electrical Work - Calculations

2.3Electric Circuits

2.3.1Series Circuits

2.3.2Series Circuits 2

2.3.3Series Circuits - Calculations

2.3.4Parallel Circuits

2.3.5Parallel Circuits 2

2.3.6Parallel Circuits - Calculations

2.3.7Grade 9 - Circuits

2.3.8Exam-Style Questions - Electricity

2.4Electricity in Homes

2.4.1Domestic Uses

2.4.2Domestic Uses 2

2.4.3Domestic Uses - Calculations

2.4.4Electrical Safety

2.4.5Electrical Safety 2

2.4.6End of Topic Test - Electricity

2.5Static Electricity

2.5.1Static Electricity

2.5.2Static Electricity 2

3Particle Model of Matter

3.1States of Matter

3.1.1Atomic Structure

3.1.2Atomic Structure 2

3.1.3Density

3.1.4Density - Calculations

3.1.5Changes of State

3.1.6Exam-Style Questions - Density

3.2Heat

3.2.1Internal Energy

3.2.2Heat Capacities

3.2.3Internal Energy - Calculations

3.2.4Latent Heat

3.2.5Latent Heat - Calculations

3.2.6Latent Heat Experiments

3.3Particle Motion in Gases

3.3.1Particle Motion in Gases

3.3.2Particle Motion in Gases 2

3.3.3End of Topic Test - Particle Model of Matter

3.3.4Grade 9 - Particle Model of Matter

3.3.5Exam-Style Questions - Specific Heat Capacity

4Atoms & Radiation

4.1Atoms

4.1.1Atomic Model

4.1.2Atomic Model 2

4.1.3Atoms & Ions

4.1.4Isotopes

4.1.5Exam-Style Questions - Atomic Structure

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

5.1.1Basics of Motion

5.1.2Basics of Motion 2

5.1.3Basics of Motion 3

5.1.4Distance- & Speed-Time Graphs

5.1.5Average Speed - Calculations

5.1.6Acceleration - Calculations

5.1.7Uniform Acceleration - Calculations

5.1.8Grade 9 - Motion

5.1.9Exam-Style Questions - 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

5.3.1Acceleration

5.3.2Acceleration 2

5.3.3Momentum

5.3.4Change in Momentum - Calculations

5.3.5Momentum - Calculations

5.3.6Moments

5.3.7Moments - Calculations

5.3.8Circular Motion

5.3.9Levers & Gears

5.3.10Stopping Distance

5.3.11Decelerations

5.3.12Stopping Distance - Calculations

5.4Pressure

5.4.1Pressure

5.4.2Pressure - Calculations

5.4.3Liquid Pressure - Calculations

5.4.4Pressure Changes

5.4.5End of Topic Test - Forces

5.4.6Exam-Style Questions - Pressure

6Waves

6.1Wave Basics

6.1.1Basics & Formula

6.1.2Wave Speed - Calculations

6.1.3Describing Waves

6.1.4Wave Frequency - Calculations

6.1.5Transverse & Longitudinal Waves

6.1.6Required Practical - Ripple Tank

6.2Waves at a Boundary

6.2.1Waves at a Boundary

6.2.2Waves at a Boundary 2

6.3Sound Waves

6.3.1Sound Waves

6.3.2Sound Waves 2

6.3.3Uses of Sound Waves

6.3.4Sound Waves - Calculations

6.3.5End of Topic Test - Introduction to Waves

6.3.6Exam-Style Questions - Wave Speed

6.4Electromagnetic Waves

6.4.1Properties

6.4.2Gamma, X-Ray & UV Light

6.4.3Infrared, Microwave & Radio Waves

6.4.4Properties 2

6.4.5Visible Light

6.4.6Visible Light 2

6.4.7Grade 9 - Waves

6.5Lenses

6.5.1Lenses

6.5.2Lenses - Calculations

6.5.3Images & Ray Diagrams

6.6Heat & Radiation

6.6.1Infrared Radiation

6.6.2Temperature

6.6.3Greenhouse Effect

6.6.4End of Topic Test - EM Waves, Lenses & Heat

6.6.5Exam-Style Questions - EM Radiation

7Magnetism

7.1Magnetism Basics

7.1.1Magnetic Materials

7.1.2Magnetic Fields

7.2Electromagnetism

7.2.1Electromagnetism

7.2.2Electromagnetism 2

7.2.3Motor Effect

7.2.4Magnetic Flux - Calculations

7.2.5Motors

7.2.6Induced Potential

7.2.7Induced Potential 2

7.2.8Generator Effect

7.2.9Generator Effect 2

7.3Transformers

7.3.1Transformers

7.3.2Transformers 2

7.3.3Transformers 3

7.3.4Transformers - Calculations

7.3.5Transformers 2 - Calculations

7.3.6End of Topic Test - Magnetism

7.3.7Grade 9 - Transformers

7.3.8Exam-Style Questions - Magnetic Fields

8Astrophysics

8.1Astrophysics

8.1.1The Solar System

8.1.2The Solar System - Calculations

8.1.3Orbits

8.1.4Orbits HyperLearning

8.1.5Life Cycle of a Star

8.1.6The Universe

8.1.7End of Topic Test - Astrophysics

8.1.8Exam-Style Questions - Astrophysics

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Density - Calculations

Exam-Style Questions - Density