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Matter – States of Matter, Properties and Changes
Matter
Matter takes up space and has massMatter is made of atoms, usually
chemically bonded into moleculesExists in different states
States of Matter
There are 4 states of matter: solid, liquid, gas, and plasma
State of a sample of matter depends on the kinetic energy of the molecules or atoms in the sample
Kinetic energy is the energy of moving things
Kinetic Energy
Kinetic energy is the energy of moving things
Kinetic energy moves from areas of higher energy to areas of lower energy
High energy low energy
Kinetic energy is measured in Joules (J)
Solids
Solids have a definite shape and a definite volume
The atoms and molecules that make a solid, vibrate in place but do not move around
Kinetic Theory of Matter, Solids
Particles in solid matter are held close together by forces between them
Particles vibrate but don’t have enough energy to move out of position
Liquids
Liquids have a fixed volume, but take the shape of the container in which they are found
The atoms and molecules that make a liquid can flow around each other
Kinetic Theory of Matter, LiquidsParticles in liquid matter are held
close together by forces between them
Particles are close enough so that liquid matter has a definite volume
Particles have enough energy to move over and around each other
Gases
Gases have neither a definite shape nor volume
They take the shape of their container
Kinetic Theory of Matter, GasesParticles of a gas have enough
energy to separate completely from one another
Particles of a gas are not close together so they can be squeezed into a smaller space
Particles have enough energy to move in all directions until they have spread evenly throughout their container
Plasma
Plasma is a gaslike mixture of positively and negatively charged particles
They have so much energy that they collide violently and break apart into charged particles
Found in lightning bolts, neon signs, Northern lights, and stars
Plasma, cont.
It is made of electrons and positive ions that have been knocked apart by collisions at very high temperatures or in situations where the matter has absorbed energy
Least common state of matter on Earth but is the most common state of matter in the universe, because stars are made of matter in the plasma state
Thermal Expansion
Almost all matter expands when it gets hotter and contracts when it cools
When matter is heated the particles move faster, vibrate against each other with more force
Particles spread apart slightly in all directions and the matter expands
Thermal Expansion, cont. This effect happens in solids, liquids,
and gasesExamples are the liquid in a
thermometer and expansion joints in roads and buildings
Changes of State
When matter gains or loses energy, it can change from one state to another
Different states of matter correspond to different amounts of energy, these amounts are specific to particular kinds of matter
Temperature can be used to measure the amounts of energy present in the matter
Change of state terms Boiling: liquid changes to a gas Freezing: liquid changes to a solid Condensing: gas changes to a liquid Melting: solid changes to a liquid Evaporating: liquid changes to a gas (but a
temperatures lower than the boiling point) Subliming: solid changes into a gas
without becoming liquid (opposite of sublimation is deposition)
Change of state temperaturesBoiling point: temperature at which a
liquid becomes a gas, this temperature is an identifiable characteristic for different substances
Melting point: temperature at which a solid becomes a liquid
Substances condense or boil at their boiling point, depending on whether energy is being added or taken away
Substances melt or freeze at their melting point, depending on whether energy is being added or taken away
Phase changes
Transitions between solid, liquid, and gaseous phases typically involve large amounts of energy compared to the energy needed to change the temperature of a solid or liquid or gas.
It takes lots of energy to change states (temperature stays constant until state is completely changed).
If heat were added at a constant rate to a mass of ice to take it through its phase changes from solid to liquid water and then to steam, the energies required to accomplish the phase changes would lead to plateaus in the temperature vs time graph.
Boiling point elevation
http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/propOfSoln/colligative.html interactive boiling point and freezing point changes
Adding solute to water increases its boiling point, the solute interacts with the water and energy must be added to overcome the interactions so that the water can then change from a liquid to a gas
Freezing point depressionhttp://group.chem.iastate.edu/Green
bowe/sections/projectfolder/flashfiles/propOfSoln/colligative.html interactive boiling point and freezing point changes
Adding solute to water decreases its freezing point, the solute interacts with the water and energy must be removed to overcome the interactions so that the water can then change from a liquid to a solid
Thermal Energy
Thermal energy is the total energy of the particles in a material
Thermal energy includes the kinetic energy of the particles (their motion or vibration)
Thermal energy also includes the potential energy of the particles (energy due to forces acting within or between the particles)
Heat
Heat is the name given to thermal energy that moves or is transferred
In many things that you read, heat and thermal energy are used interchangeably
Movement of Heat
Heat moves from areas of greater heat (more thermal energy) to areas of lesser heat (less thermal energy)
http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/specificheat.html
Temperature
Temperature is the measure of the average kinetic energy of the particles that make up a sample of matter.
As the particles move faster, the temperature rises
As the particles slow down, the temperature falls
Law of Conservation of EnergyLaw of Conservation of Energy –
Energy is neither created nor destroyed. It can change forms.
Heat transfer follows the Law of Conservation of Energy
Energy transfers from areas of high energy to areas of low energy but can neither be created nor destroyed
Thermometers
Liquid inside the thermometer is made of molecules
As kinetic energy of molecules increases, liquid molecules move faster and liquid expands
Liquid rises in the tube inside the thermometer
Thermometers
Rising kinetic energy = rising liquid = rising temperature on thermometer scale
Heating and cooling a thermometer: http://www.middleschoolchemistry.com/multimedia/chapter1/lesson3
Temperature scales - FahrenheitFirst scale developed
Water melts/freezes at 32°F and boils at 212°F
Salt water melts/freezes at 0°F, body temperature was 96°F and degrees were divided into 12s and then into 8s between these two points
Temperature scales - CelsiusCelsius scale based on 100 degrees
between freezing and melting of water
Water melts/freezes at 0°C and boils at 100°C
Temperature scales - Kelvin Important scale used in most of
science
Based on a single point (absolute zero) which is given a value of 0 degrees.
From there, the scale increases by degrees that are the same size as Celsius degrees.
Temperature scales - Kelvin It is a scale that is based on energy
content, rather than on arbitrary temperature values like the other two scales (based on water).
Water freezes at the value 273.15 K and boils at 373.15 Kelvin.
Absolute Zero
0 on the Kelvin scale
Point at which all particle motion stops
Matter has no thermal energy at absolute zero
Law of Conservation of EnergyLaw of Conservation of Energy –
Energy is neither created nor destroyed. It can change forms.
Heat transfer follows the Law of Conservation of Energy
Energy transfers from areas of high energy to areas of low energy but can neither be created nor destroyed
Specific Heat Capacity
Physical property of matterRelates to a substance’s ability to
absorb heatAlso called specific heat
Specific Heat Capacity
Specific heat capacity of a substance is the amount of energy (Joules) required to raise the temperature of 1 gram of the substance by 1 °C
Specific heat capacity =
Objects with low specific heat capacities heat up more quickly than objects with high specific heat capacities.
It takes less energy to raise their temperatures
They also transfer their heat more quickly so they cool down faster
Water has a fairly high specific heat capacity, 4.184 J/g °C
This means it takes a lot of energy to raise the temperature of water 1 °C compared to the amount of energy it takes to heat something with a lower specific heat capacity
Example: Iron (0.45 J/g °C) needs much less energy to change its temperature
Heat conductors and insulatorsObjects with low specific heat
capacities are better conductors of heat
Objects with high specific heat capacities are better insulators because they don’t heat up as quickly
Calorimeter
An insulated container that prevents a chemical reaction from gaining heat from its surroundings or losing heat to its surroundings
Using a calorimeter to calculate specific heat capacityCalorimeter experiments to calculate
specific heat capacities of objects use the Law of Conservation of Energy and the known specific heat capacity of water
When a heated object is placed in a cup of cold water, the heat will move from the object to the water
When the temperature stops changing, the temperature of the object and water are now the same
Using a calorimeter to calculate specific heat capacityWhen the temperature stops
changing, the temperature of the object and water are now the same
Energy transferred to the water is equal to the energy transferred from the object
Calculations:Known:
Specific heat capacity of water = 4.184 J/g °C
Energy transferred to water = mass of water (g) x Temp change (°C) x
4.184 J/g °C
Specific heat capacity of object =
Links for extra activities in Investigation 1p. 22 heating and cooling gas in a
bottlehttp://www.middleschoolchemistry.co
m/multimedia/chapter1/lesson5
p. 24 heating and cooling a metal ball
http://www.middleschoolchemistry.com/multimedia/chapter1/lesson4