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)


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


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.


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


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


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


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



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




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)




Extension

Can you think of a solid that is not crystalline?

What type of structure does it have?




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


Do these diagrams show particle spacings correctly?

First, some definitions:

1. write an equation to define density;

2. explain the meaning of ‘STP’.


Particle spacing: refining our ideas LOs

STP: a temperature of 0 C and a pressure of 100 kPa (approx. 1 atmosphere)


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




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?




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




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.




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.


Particle in solids, liquids and gases LOs


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.


Particle in solids, liquids and gases LOs


oil

oil

Estimating the size of an oil molecule LOs


Estimating the size of an oil molecule LOs

tp 1 solids, liquids & gases (shared)

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