2.1 Simple Kinetic Molecular Model of Matter

2.1.1 States of matter
Core
• State the distinguishing properties of solids, liquids and gases

GCSE Physics Revision: Solids, liquids and gases from youtube.com

The kinetic model of matter

State of matter
Model
Properties
Arrangement of particles
Movement of particles
Solid
Draw molecular structure
- Fixed shape and volume
- Normally hard and rigid; a large force is needed to change its shape
- High density
- Incompressible
Closely packed together, usually in a regular pattern, occupying minimum space
High density
Vibrate about fixed positions
Higher vibration in higher temperature
Held in position by very strong intermolecular bonds >>explain why solids have fixed volumes and shapes
Liquid
Draw molecular structure
- Fixed volume but does not have a fixed shape
- High density
- Incompressible
Randomly arranged with the particles slightly further apart as compared to that of solid.
Relatively high density
Free to move about but confined within the vessel containing it.
Molecules can vibrate and move but are held close together by strong bonds
>>explain why liquids have fixed volume but will take the shape of vessels containing them.
Gas
Draw molecular structure
- No fixed shape or volume
>> Expands to fill container
- Low density
- Compressible
Very far apart. Particles are randomly arranged and will occupy any available space.
Low density
Particles exert a pressure on their container.
Particles have very little attraction between them and move about randomly in linear motion at a very high speed
    • explain why gases have no fixed volume and shape
Gases are highly compressible.


Image from Solids Liquids Gases and Particle Model from youtube.com
Plenery Particle Model of solids, liquids and gases.ppt

2.1.2 Molecular model
Core
Describe qualitatively the molecular structure of solids, liquids and gases in terms of the arrangement, separation and motion of the molecules
Task- worksheet
State
Arrangement and spearation of particles
Movement of particles
Solid
The particles are closely packed together.
The particles vibrate about a fixed position.The hotter the solid, the more they vibrate.
Liquid
The particles are packed slightly less closely together when comparing with solid and the arrangement is slightly more jumbled.
The particles vibrate and can move passing each other in the liquid.
Gas
The particles are widely spread out and are no longer in contact.
The particles move freely about, collide each other and bounce off the walls of their container.

Supplement
Relate the properties of solids, liquids and gases to the forces and distances between molecules and to the motion of the molecules
Molecules in Solids of Eureka episode from Youtube.com
Monecules in Liquids of Eureka episode from Youtube.com



Keywords
Description
Particle theory
Matter is made from particles.
Matter
Something that has mass and takes up space. It is the material that everything is made of in the universe.
Substance
That which has mass and occupies space; matter.
Material
Something that has mass and exists as a solid, liquid, gas. The matter from which a thing is or can be made.
ex) Wood, Metal, Glass, Plastic
Lattice
A regular, periodic arrangement of particles.
Nature of Matter and Changes of State from youtube.com

BBC GCSE Kinetic Particle Theory Revision

Core
Interpret the temperature of a gas in terms of the motion of its molecules
The temperature of a substance is related to the molecular velocity of particles. The higher the temperature of a gas, the faster the movement of particles.

Kelvin is a temperature scale in a measure of motion/KINETIC ENERGY of gas particles. It is also known as thermodynamic temperature scale.
°C + 273 = K

ex) What temperature of Kevin is same as 49°C =

322 K
0 K = Zero kelvin = absolute zero temperature. At this temperature, the particles have no kinetic energy.

Describe qualitatively the pressure of a gas in terms of the motion of its molecules
- How does a gas exert pressure?
Hint)Balloon: The more air you blow into the balloon, the greater the pressure of gas becomes.

A) For a fixed mass of gas, how gas particles exert pressure?
Gas particles bounce each other and collide to the walls. This exerts force on the surface of the walls of its container.
B) For a fixed mass of gas, how can you make gas particles exert bigger pressure?
Heat up the gas particles.
C) What happens to gas particles when they are heated?
They gain more energy and it results in increase of kinetic energy as they collide more frequently.

  • Gas particles exert pressure on the walls of its container due to the collisions of its particles with the walls. The particles exerts a force as they bounce off the walls. The greater the collisions between the particles and the walls, the greater the pressure becomes.

D) What happens to pressure of a fixed mass gas when it is compressed?
The molecular movement of a gas increases.
If the gas is compressed to half of its original volume, its pressure doubles up at a constant temperature.
2.1.4 Pressure changes
Describe qualitatively, in terms of molecules, the effect on the pressure of a gas of:
- a change of temperature at constant volume
- a change of volume at constant temperature

Describe Pressure - Volume relationship of a gas at constant temperature

Gizmo class code: 9LZTVC4CKC

Gas Properties
Click to Run

Gas properties simulation from Phet
While downloading the simulation, think of the questions below.
  1. How would the volume of a gas change if the pressure was doubled up?
  2. Can you write an expression to describe how changes in pressure affect the volume of a gas? [Example: V = nR ÷ P, where nR is a proportionality constant.]
  3. How would the volume of a gas change if the temperature was divided by 2?
  4. Can you write an expression to describe how changes in temperature affect volume? [Example: V = nR × T, where nR is a proportionality constant.]
  5. The simulation is not completely realistic because it doesn’t include atmospheric pressure. How would the results change if atmospheric pressure was included?
Ideal Gas Properties << Class notes
  • Pressure in gases is due to the collision of molecules with the walls of the container.
  • The pressure of a fixed mass of gas, pressure P , is directly proportional to its absolute temperature T when its volume V is constant.
  • The volume V of a fixed mass of a gas increases proportionally with the increase in absolute temperature T while pressure remains constant.
  • The volume of a fixed mass of gas, volume (V) , is inversely proportional to the pressure (P) of the gas, when the absolute temperature T is held constant.

• Recall and use the equation pV = constant for a fixed mass of gas at constant temperature

IDEAL GAS LAW

pV = nRT

Pressure- Volume

( Boyle's law )

Volume-Temperature

( Charles' law )

Pressure-Temperature

(Gay Lussac's law)

The pressure p is inversely proportional to volume V.
The volume V of the gas increases proportionally with the increase in temperature T.
The pressure of a fixed mass of gas p is directly proportional to its temperature T when its volume is constant.
external image 34772d9d9626b152407dd8b135389824.png
At constant temperature, the product of an ideal gas's pressure and volume is always constant.
external image 29fb9f82f12f11cdbafb1ee057d7e085.png
For an ideal gas at constant pressure, the volume is directly proportional to the absolute temperature in kelvin.
external image 6c6a35ce4507d81696a7a01125715174.png
The pressure exerted on a container's sides by an ideal gas is proportional to the absolute temperature of the gas at a constant volume.
Core
•Show an understanding of the random motion of particles in a suspension as evidence for the kinetic molecular model of matter
•Describe this motion (sometimes known as Brownian motion) in terms of random molecular bombardment
Supplement
•Show an appreciation that massive particles may be moved by light, fast- moving molecules
A Brownian motion applet from www.math.rutgers.edu
Brownian motion applet 2 from Tim's Brownian motion applet

Brownian motion-Pollen grains in water from youtube.com
Brownian motion BBC Bitesize
Smoke particles are moved randomly. This motion is caused by collisions between smoke particles and air particles which are also moved randomly. The air particles cannot be seen but their motion can be explained by the random movement of the smoke particles.

2.1.3 Evaporation
Core
•Describe evaporation in terms of the escape of more-energetic molecules from the surface of a liquid
•Relate evaporation to the consequent cooling of the liquid
At a temperature, there is average kinetic energy in liquid. Evaporation happens when molecules with high kinetic energy escape the liquid and become a gas. As a result, the average kinetic energy of the molecules in the liquid decreases and thus the temperature of the liquid also decreases.

Evaporation and Condensation of Eureka episode from Youtube.com

Supplement
• Demonstrate an understanding of how temperature, surface area and draught over a surface influence evaporation.
• Explain the cooling of a body in contact with an evaporating liquid.
The higher the temperature, the higher the kinetic energy. The bigger the surface area, the easier the kinetic energy particles gain.
Draught increases evaporation as particles in high kinetic energy removes from above the surface of the liquid as molecules in the water vapour return to the liquid at around the same rate that particles escape the liquid when the air is humid. Fewer particles condense in less humid air.
2.2 Thermal properties
2.2.1 Thermal expansion of solids, liquids and gases
Core
•Describe qualitatively the thermal expansion of solids, liquids and gases at constant pressure
As particles in solids, liquids and gases vibrate more, the gap in between particles increases. Molecules are further apart and take up more space resulting in a greater volume and the thermal expansion.

•Identify and explain some of the everyday applications and consequences of thermal expansion
1. Mercury or alcohol in a thermometer expands and contracts when temperature changes.
2. Put a jar of jam in hot water to open the metal lid of a jar.
3. Gaps in between the metal railway to be left to allow expansion in hot days.
4. Bimetal thermostat.

Supplement
• Explain, in terms of the motion and arrangement of molecules, the relative order of the magnitude of the expansion of solids, liquids and gases





Supplement
• Explain, in terms of the motion and arrangement of molecules, the relative order of magnitude of the expansion of solids, liquids and gases
Expansion is highest in gases and lowest in solids.
States of Matter
Click to Run
States of matter simulation from Phet

Revise thermal expansion from the BBC Bitesize and quizlet

2.2.2 Measurement of temperature
Core
•Appreciate how a physical property that varies with temperature may be used for the measurement of temperature, and state examples of such properties
1. Mercury or alcohol thermometer: The physical property of thermal expansion when temperature changes used for the measurement of temperature. The amount of expansion can be matched to a temperature on the scale.
2. Thermistor thermometer: A probe contains a thermistor. It becomes a better electric conductor when temperature rises. The higher the current flows, the higher the temperature reading in the probe.
3. Thermocouple thermometer: A probe consists of two different metal wires in two junctions. The different temperature in two junctions causes a tiny voltage which makes current flows. The greater the temperature difference, the greater the current flows. Digital meter measures current and converts to a temperature reading. Thermocouple thermometers are used for recording rapid high temperature reading and have a large range of -200 oC to 1100 oC.
•Recognise the need for and identify fixed points
Lower fixed point: freezing point of pure water(melting point of ice).
Upper fixed point: boiling point of pure water(condensing point of steam).

To calibrate a Celsius thermometer, place a thermometer in melting ice to indicate 0 oC and in boiling water to indicate 100 oC.
•Describe and explain the structure and action of liquid-in-glass thermometers
Liquid in glass thermometer: The liquid of mercury or alcohol expands or contracts as temperature rises or falls.

Measuring temperature of Eureka episode from Youtube.com

Supplement
• Demonstrate understanding of sensitivity, range and linearity
• Describe and explain how the structure of a liquid-in-glass thermometer relates to its sensitivity, range and linearity
Sensitivity: To make expansion of liquid greater in distance by putting it in a narrower tube, to increase the sensitivity of thermometer. Sensitivity can be increased by using a material that expands more for the same degree of temperature change. ex) Alcohol expands more than mercury but its expansion is non linear.
Range: The maximum and minimum temperature of thermometers.
ex) low range: 0 oC to 100 oC
high range: 0 oC to 500 oC.
Linearity: Directly proportional change in two related quantities:
Linearity.jpg

•Describe the structure of a thermocouple and show understanding of its use for measuring high temperatures and those that vary rapidly
Thermocouple: a thermoelectric device for measuring temperature, consisting of two wires of different metals connected at two points, a voltage being developed between the two junctions in proportion to the temperature difference.

2.2.3 Thermal capacity (heat capacity)
Core
•Relate a rise in the temperature of a body to an increase in internal energy

Internal energy is the sum of the potential energy and random kinetic energy of all its particles.

Internal Energy: The energy contained in an object due to random kinetic energy and total potential energy of the molecules of the substance.

Temperature is a measure of the average kinetic energy of the particles. If temperature rises this indicates that the kinetic energy of the particles has increased. If the kinetic energy of the particles increases so does the internal energy.
The force of attraction between particles gives them potential energy.
Heat and Energy of Eureka episode from Youtube.com

In a gas the particles are so far apart that there is no potential energy – all energy is kinetic and shared randomly between all the particles.
Thermal equilibrium occurs when no heat is being transferred between an object and its surroundings.
If a gas is in thermal equilibrium and it is not being compressed or expanded, the average kinetic energy of its molecules will remain constant and the temperature will stay the same.

•Show an understanding of what is meant by the term thermal capacity of a body
Thermal Capacity [C] :
Thermal capacity[C]----is the amount of thermal energy required to raise the temperature of a body by 1K/1oC.

Thermal Properties of Matter-Heat capacity[C] C = Q/ΔΘ ;

Q = Thermal energy absorbed in J.
C = heat capacity, Unit ( J K-1 or J oC )
ΔΘ = change in temperature in K or oC.
Thermal capacity depends on the mass and the material of the object.

Supplement
• Give a simple molecular account of an increase in internal energy
• Recall and use the equation thermal capacity = mc
• Define specific heat capacity
• Describe an experiment to measure the specific heat capacity of a substance
• Recall and use the equation change in energy = mc∆T
Specific Heat Capacity [c] :
Specific Heat Capacity [c]----is the thermal capacity per unit mass; the amount of thermal energy required to raise the temperature of 1 kg (unit mass) of a substance by 1 K or 1 oC.

Thermal Properties of Matter-Specific Heat Capacity [c]

Q = mc(ΔΘ)

Thermal energy transferred = mass x specific heat capacity x temperature change

c = specific heat capacity,
Q = thermal energy absorbed or released,
ΔΘ = the temperature change,
m = mass of substance. Unit( J kg-1 K-1 or J kg-1 oC )

The relationship between heat(thermal) capacity C and specific heat capacity c. ; C = mc
c = C/m = Q/m ΔΘ
For the same amount of thermal energy supplied, materials of lower specific heat capacity will heat up to a higher temperature than materials with higher specific heat capacity.]]For the same amount of thermal energy supplied, materials of lower specific heat capacity will heat up to a higher temperature than materials with higher specific heat capacity.



The amount of thermal energy the colder object gains is equal to the amount of thermal energy the hotter object loses

Questions on SHC


Aim: To investigate the specific latent heat of an unknown object

Importance of Specific Heat - Please do not copy the below.

The specific heat of a substance is an important physical property because it tells us the suitability of a given substance for a specific purpose. Aluminium vessels are used in cooking because aluminium is a light metal. Hence, for a given volume, its thermal capacity will be less than that of vessels made of steel of same volume.
The high specific heat of water explains why land close to a large pond of water is likely to have a milder climate than land without a pond close by. Because of high specific heat, water on the land gets heated slowly. Land near the pond also gets heated slowly. For the same amount of heat, dry land gets heated quickly to a much higher temperature. Soil is a poor conductor, prevents the heat from going deep into the ground. Hence, the heat causes a quick rise in temperature on dry land. For same reasons, land areas far from water-cool off much faster than land near large bodies of water.

2.2.4 Melting and boiling
Core
•Describe melting and boiling in terms of energy input without a change in temperature
•State the meaning of melting point and boiling point
•Describe condensation and solidification in terms of molecules

Aim: Students should be familiar with the terms melting, freezing, evaporating, boiling and condensing and should be able to describe each in terms of the changes in molecular potential and random kinetic energies of molecules.

Draw phase change diagram for water - 3 minutes



Changes of States of Matter from Teacher's pet youtube.com
State changes from BBC Bitesize

Describe and explain the process of phase changes in terms of molecular behaviour.

Melting: It is a process of changing state from solid to liquid

Freezing: It is a process of changing state from liquid to solid

Condensing: It is a process of changing state from gas to liquid

Sublimation: It is a process of changing state directly from the solid to the gaseous state or from the gaseous to the solid state without becoming a liquid

Boiling: It is a process of changing state from liquid to gas

•Distinguish between boiling and evaporation

Evaporation: It is a process of becoming a vapor at a temperature below the boiling point. This results in a cooling of the liquid.

Evaporation takes place at the surface of a liquid, where molecules with the highest kinetic energy are able to escape.
Boiling
Evaporation
1. Occurs at a fixed temperature.
2. Takes place throughout the liquid.
3. Bubbles are formed in the liquid.
4. Temperature remains constant.
5. Thermal energy supplied by an energy source.
1. Occurs at any temperature.
2. Takes place only at the liquid surface.
3. No bubbles are formed in the liquid.
4. Temperature may change.
5. Thermal energy supplied by the surroundings.

Water changes its state from liquid to gas(steam) by boiling as the temperature goes up.

Steam also changes state to water by the process called condensation and water goes back to the state of ice by freezing as the temperature decreases. The flat line on your graph shows where energy is being used to break bonds – this has to be done during melting/boiling.

Why does the temperature stay at 0 degree Celsius when ice is melting? Explain your answer using the word energy.

Supplement
•Use the terms latent heat of vaporisation and latent heat of fusion and give a molecular interpretation of latent heat
Specific Latent Heat: The amount of thermal energy required to change the state of 1 kg of a substance without a change in temperature. SLH of fusion is solid to liquid, SLH of vaporisation is liquid to gas. Q = mL

• Describe an experiment to measure specific latent heats for steam and for ice
• Recall and use the equation energy = ml

Investigating latent heat

To measure specific latent heats for ice
To measure specific latent heats for steam
The latent heat of water can be determined in the following way:
  1. an electrical heater is used to melt ice for several minutes
  2. the electrical energy used is calculated by multiplying the power of the heater by time
  3. the mass of water melted is recorded and the relationship between energy input and mass is calculated
  4. the amount of heat needed to change one kilogram of ice (the latent heat) is then determined
Research your method and describe it.
Specific latent heat from BBC Bitesize
2.3 Transfer of thermal energy

Three Activities for heat transfer
Activity 1. Using the guide watch each video(conduction, convection, radiation) and record your responses and answers to the questions on the worksheet.

2.3.1 Conduction
Core
• Describe experiments to demonstrate the properties of good and bad conductors of heat
Small objects are attached to a stick/pole of different conductors by wax to be tested.
The ability to conduct heat of the material can be judged by how quickly wax melts and the small objects are released.

Supplement
• Give a simple molecular account of conduction in solids including lattice vibration and transfer by electrons
Collisions among particles cause energy transfer

Conduction of Eureka episode 24 from Youtube.com

2.3.2 Convection
Core
Recognise convection as an important method of thermal transfer in fluids

• Relate convection in fluids to density changes and describe experiments to illustrate convection

Convection of Eureka episode 27 from Youtube.com
The actual transfer of molecules/particles from one region to another. Usually the dominant method of heat transfer in liquids and gases
Ex) Water in a pot, Air in a room: Hot air is less dense so it rises. Cold air is more dense so it sinks.

2.3.3 Radiation
Core
• Identify infra-red radiation as part of the electromagnetic spectrum
• Recognise that thermal energy transfer by radiation does not require a medium
• Describe the effect of surface colour (black or white) and texture (dull or shiny) on the emission, absorption and reflection of radiation
em_spectrum.png

Thermal Energy Travels as EM Waves
Supplement
• Describe experiments to show the properties of good and bad emitters and good and bad absorbers of infra-red radiation
• Show understanding that the amount of radiation emitted also depends on the surface temperature and surface area of a body
Radiation

Radiation of Eureka episode 29 from Youtube.com

Silver is a good reflector but poor absorber and poor emitter of radiation while black is good at absorbing and emitting of radiation.

Activity 2. Listen to the Heat Transfer Song and try to sing along. Then watch the Heat Transfer Flash. Don't forget to take notes on examples of each method of heat transfer.

Heat transfer song by Mr.Parr from youtube.com


Activity 3. Choose one of the articles below. You may choose an article (based on lexile level or topic of interest, just remember that the higher the lexile the more difficult the reading). Click and download on the icon to read the article(s). Write your answers to the questions below as you read on the worksheet.




Questions for Activity 3 (Answer on your worksheet):
  1. Which did you read?
  2. How does your article define heat?
  3. According to the article you read, how is heat important to us?
  4. What are the 3 ways heat can travel?
  5. Write the definition and an example from the article of each method of heat transfer.
    conduction
    convection
    radiation

How does heat travel? from coolcosmos.ipac.caltech.edu
Heat energy transfer from BBC Bitesize

Exit ticket assignment: Making a word window.


On a piece of paper,draw diagrams showing the similarities & differences between the 3 methods of heat transfer - radiation &
convection & conduction. Write an example of each not provided in class or in the articles or videos and add short descriptions IN YOUR OWN WORDS & LANGUAGE.

ATTACH YOUR COMPLETED WORK TO THE WINDOW/DOOR.


Homework:

Lip sync contest: Practice the heat transfer song for the grand prize of SNICKERS chocolate bar.


Challenge
mad scientist
mad scientist

Choice #1 – Demonstrate an experiment on conduction, convection, OR radiation.
  1. Gather the materials you need to complete the experiment.
  2. Practice the experiment once before the demonstration.
  3. Remember you will need to explain why your experiment is on conduction, convection OR radiation. You will also state why it is not the other two ways heat is transferred.
  4. Demonstrate your experiment for at least 3 students.
video camera
video camera

Choice # 2 – Video tape you demonstrating one experiment on conduction, convection, OR radiation.
  1. Gather the materials you need to complete the experiment.
  2. Practice the experiment once before you video tape.
  3. Ask someone to video tape you demonstrating your experiment.
  4. Remember you will need to explain why your experiment is on conduction, convection OR radiation. You will also state why it is not the other two ways heat is transferred.
  5. Show your video to at least 3 students.
Resources





2.3.4 Consequences of energy transfer
Core
• Identify and explain some of the everyday applications and consequences of conduction, convection and radiation
Conduction Convection Radiation puzzle
Conduction: Cookers are made of good conductors of metals.
Convection: Air conditioners are usually installed on the ceiling or at a high position as cold air drops.
Radiation: Houses in hot climates are painted more white.


Write a story, draw pictures or create a collage.

  1. Identify one real-life experience for conduction, convection and radiation.
  2. Write your story or draw a picture for each experience. The collage can include all 3 on one page.
  3. Remember you will need to explain how each example is not the other two ways heat is transferred. For example, if you real-life experience is an example of conduction, you need to state why it is conduction and why it is not convection and radiation.
  4. Share your product with at least 3 students.



Thermal Physics
Heat transfer Let's play Kahoot!
Energy transfer by heating from BBC Bitesize