Tp 1 solids, liquids & gases (shared)
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Transcript of Tp 1 solids, liquids & gases (shared)
Thermal physicsThermal physics
A-level Physics
Unit G484: The Newtonian World
Solids, liquids & gases (1)
A-level Physics
Unit G484: The Newtonian World
Solids, liquids & gases (1)
Thermal physicsThermal physics
Learning objectives
At the end of the lesson you will be able to:
• describe a simple kinetic model for solids, liquids and gases;
• describe solids, liquids and gases in terms of the spacing, ordering
and motion of atoms or molecules.
Lesson focus• solids, liquids & gases - 1
Thermal physicsThermal physics
Learning outcomes
All of you should be able to
• draw diagrams to show the arrangement of particles in solids,
liquids and gases;
• describe the motion of particles in solids, liquids and gases
Most of you may be able to
• explain what is meant by a kinetic model of matter.
Thermal physicsThermal physics
Solids, liquids and gases: KS2 recall
State (or phase) of
matter
Characteristic property (KS2)
What does this property tell us about
the forces between particles?
Can matter in this state
be compressed?
What does this tell us about the
spacing of particles in this
state?
solidHas a fixed shape and
volume
liquidFlows and fills
the bottom of a container
gas Fills its container
Is there a contradiction here? If so, how can it be resolved?discussionMini prac: compressibility of liquids & gases
LOs
Thermal physicsThermal physics
State (or phase) of
matter
Characteristic property (KS2)
What does this property tell us about
the forces between particles?
Can matter in this state be compressed?
What does this tell us about the
spacing of particles in this
state?
solid Has a fixed shape and volume relatively strong no very close
liquidFlows and fills
the bottom of a container
weaker than in solids
almost incompressible
close but slightly less so than in solids
gas Fills its container very weak yes far part
discussion
Solids, liquids and gases: KS2 recall LOs
Thermal physicsThermal physics
The kinetic theory of matter states that matter is composed of a very large
number of very small particles that are in constant, random motion.
To answer (pairs)
1. Why is this a useful model?
2. What observations does it explain? (e.g. the expansion of solids,
liquids and gases when heated)
The kinetic theory is useful because it explains a wide range of phenomena,
including expansion, thermal conduction, diffusion and gas pressure.
LO1: describe a simple kinetic model for solids, liquids and gases
The kinetic theory of matter LOs
Thermal physicsThermal physics
To do
Make sketches to show particles in solids, liquids and gases.
Pay particular attention to the• spacing• ordering of particles
You probably drew something like this:
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
The kinetic theory of matter LOs
Thermal physicsThermal physics
What evidence is there for this ordering in solids?
Many solids are crystalline (crystal = solid with ‘long range’
ordering of its particles).
galvanised (zinc plated) surfaces
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
The kinetic theory of matter LOs
Thermal physicsThermal physics
What evidence is there for this ordering in solids?
Many solids are crystalline (crystal = solid with ‘long range’
ordering of its particles).
halite (rock salt – sodium chloride)
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
The kinetic theory of matter LOs
Thermal physicsThermal physics
Extension
Can you think of a solid that is not crystalline?
What type of structure does it have?
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
The kinetic theory of matter LOs
Thermal physicsThermal physics
Learning objectives
At the end of the lesson you will be able to:
• describe a simple kinetic model for solids, liquids and gases;
• describe solids, liquids and gases in terms of the spacing, ordering and
motion of atoms or molecules.
Lesson focus• solids, liquids & gases - 1
Thermal physicsThermal physics
Do these diagrams show particle spacings correctly?
First, some definitions:
1. write an equation to define density;
2. explain the meaning of ‘STP’.
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
Particle spacing: refining our ideas LOs
STP: a temperature of 0 C and a pressure of 100 kPa (approx. 1 atmosphere)
Thermal physicsThermal physics
Density of water
solid / kg m-3 liquid / kg m-3 gas / kg m-3
920 1000 0.59 *
The mass of a water molecule is 3.0 x 10-26 kg .
Calculate the number of molecules in one cubic metre of solid,
liquid and gaseous water.
1 m3 of ice contains920 kg
3.0 x 10-26 kg= 3.1 x 1028 molecules
1 m3 of water contains 3.3 x 1028 molecules
1 m3 of steam contains 2.0 x 1025 molecules
* at boiling point
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
Particle spacing: refining our ideas LOs
Thermal physicsThermal physics
1 m3 of ice contains920 kg
3.0 x 10-26 kg= 3.1 x 1028 molecules
1 m3 of water contains 3.3 x 1028 molecules
1 m3 of steam contains 2.0 x 1025 molecules
Question
What can you say about the average
spacing of particles in solid, liquid and
gaseous water?
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
Particle spacing: refining our ideas LOs
Thermal physicsThermal physics
Now imagine placing the molecules neatly in a box 1m x 1m x 1m. If the
molecules are separated by x m, there are 1/x molecules along each side
and (1/x)3 molecules in total.
Calculate the particle spacing, x, for solid, liquid and gaseous water.
Did your particle arrangement diagrams show the relative spacings
properly?
x
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
Particle spacing: refining our ideas LOs
Thermal physicsThermal physics
Density of oxygen
solid / kg m-3 liquid / kg m-3 gas / kg m-3
1300 1100 1.43 at STP
The mass of an oxygen molecule is 5.3 x 10-26 kg .
To do
Repeat the previous exercise to find the separations of molecules in solid, liquid and gaseous oxygen.
LO2: describe s, l & g in terms of the spacing, ordering and motion of particles
Particle spacing: refining our ideas LOs
Thermal physicsThermal physics
Solids
Particles are held in _______ positions by ________ forces. Solids with ‘long range’ ordering of their particles are ___________ (those without are termed __________). Particles _______ about fixed positions.
Liquids
Particles are held together by _______ forces but have sufficient vibrational energy to overcome these forces of attraction, and are therefore free to _____ against each other. The virtual ________________ of liquids shows that their particle spacing is __________ to that in solids
Gases
Particles are widely ___________ and move freely. They are attracted to each other very ________ . At STP, the spacing of particles in a gas is about _____ times that of that in the solid or liquid states.
LO1: describe a simple kinetic model for solids, liquids and gases
Particle in solids, liquids and gases LOs
Thermal physicsThermal physics
Solids
Particles are held in fixed positions by strong forces. Solids with ‘long range’ ordering of their particles are crystalline (those without are termed amorphous). Particles vibrate about fixed positions.
Liquids
Particles are held together by strong forces but vibrate strongly enough to overcome forces of attraction and are therefore free to move against each other. The virtual incompressibility of liquids shows that their particle spacing is similar to that in solids
Gases
Particles are widely separated and move freely. They are attracted to each other very weakly. At STP, the spacing of particles in a gas is about ten times that of that in the solid or liquid states.
LO1: describe a simple kinetic model for solids, liquids and gases
Particle in solids, liquids and gases LOs
Thermal physicsThermal physics
oil
oil
Estimating the size of an oil molecule LOs
Thermal physicsThermal physics
Estimating the size of an oil molecule LOs