Kinetic Theory

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# Kinetic Theory - PowerPoint PPT Presentation

17 November, 2014. Kinetic Theory. Keywords Boiling point, condense, evaporate, freezing point, melt, melting point, sublimation. Learning Outcomes: All students should be able to: Describe what happens at melting/freezing and boiling point Label a general cooling curve.

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## PowerPoint Slideshow about 'Kinetic Theory' - hayley-reeves

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Presentation Transcript

17 November, 2014

### Kinetic Theory

Keywords

Boiling point, condense, evaporate, freezing point, melt, melting point, sublimation

Learning Outcomes:

All students should be able to:

• Describe what happens at melting/freezing and boiling point
• Label a general cooling curve.

Most students should be able to:

• Use the particle model to explain what is happening at each point on the cooling curve
• Describe the difference between the temperatures of substances at boiling and evaporation point.

Some students should be able to:

Explain how evaporation makes a liquid cooler

States of matter and temperature

Water can be a solid, liquid or a gas

• At a cold enough temperature, even substances that are normally gases will become solid.
• At higher temperatures, solids change to become liquids or gases – as long as they do not catch fire or break down.
Changes of state

melting

boiling

condensing

freezing

Each change of state is given a different name:

sublimation

liquid

gas

solid

reverse sublimation

Changes of state – heating curve

gas

boiling 

condensing

liquid  gas

liquid

melting 

freezing

solid  liquid

solid

temperature

time

What is evaporation?

Evaporation occurs when the particles in a liquid escape to form a vapour.

Evaporation can occur at any temperature but it occurs most rapidly at a liquid’s boiling point.

The particles that escape take some energy from the remaining particles and so the temperature of the liquid falls.

Evaporation is another method of heat transfer.

Practical time

AF1 – Thinking Scientifically

AF4 – Using investigative approaches

• Practical - Stearic Acid practical – follow method teacher has shown you. (method on next slide)
• Draw your own cooling curve in your book and label each change of state
• Now complete a “triangle/arrow summary diagram in books to show all changes of state and Particle diagrams of solids/liquids/gases
Method
• Take a boiling tube of molten wax from the water bath
• Place in a boiling tube rack
• Take the temperature of the wax every minute recording the state of matter.
• Stop when the wax has been solid for 2 minutes with no temperature change
• Draw a cooling curve from your results
Plenary - Sublimation

Sublimation, reverse sublimation

OR: AB document link on page 127 opens a CLOZE exercise covering the material on page 126-127. There is also an AT presentation with the answers.

Youtube video of sublimation of dry ice: