Transcript Chemical and physical properties
Do Now • Sit SILENTLY, open your notebooks, and copy down and answer the following question about the video in your notes in your notes.
• What do you think is the main difference between physical and chemical changes?
https://www.youtube.com/watch?v=gCbqjs pqJo
Chemical and physical properties
Matter Flowchart Review
yes MATTER
Can it be physically separated?
no PURE SUBSTANCE MIXTURE yes Is the composition uniform?
Homogeneous Mixture (solution) no Heterogeneous Mixture yes
Can it be chemically decomposed?
Compound Element no
• • • Matter Every element/compound is unique in some way from all others.
If you know enough about a substance, you can figure out what it is.
If you know what a substance is, you can know all types of things about it.
Matter • All matter has 2 types of properties: Physical properties and chemical properties.
Property
•
Is a description of an object
If struck by lighting, the tree could catch FIRE (BURN) The tree is GREEN The tree is TALL
Physical Properties
• •
Are determined by the use of the senses .
They are a description five of an object.
Physical properties • A physical property is a characteristic of a substance that can be observed without changing the substance into another substance.
– (You can see it without changing what you ’ re looking at into something else.)
Physical Properties • Physical properties can be extensive or intensive: –
Extensive properties
depend on the amount of a substance that you have.
–
Intensive properties
don ’ t depend on how much you have.
Physical Properties - Examples • Examples of extensive physical properties include: – Volume – Mass – Weight – Density
Volume
• The amount of space that matter occupies.
Mass
• A measure of how much matter is in an object.
Weight
• A measure of the force of gravity on an object.
Density
• The measurement of how much mass of a substance is contained in a given volume.
• Mass/Volume
Physical Properties - Examples • Examples of intensive physical properties include: – Density – Melting point – Boiling point
• Physical Properties - Examples Other physical properties include: – Color – Hardness – Odor – Taste – State of matter – – Texture Luster (shine) – Flexibility – Heat conductivity – Electrical conductivity – Solubility (ability to dissolve in water.) – Shape – Viscosity – Ductility – Malleability
States of Matter
• • • •
There are different present.
“
states
”
of matter. No, not like Texas, Oklahoma, New Mexico. States of matter are also known as phases (a physical state of matter). Elements and compounds can move from one phase to another phase when special physical forces are Solid Liquid Gas
What is happening at the atomic level
Freezing point
• The temperature at which a liquid changes into a solid.
B. Four States of Matter • Solids – particles vibrate but can ’ t move around – fixed shape – fixed volume – incompressible
• •
Melting point
The temperatures at which the solid form of the element or compound is at equilibrium with the liquid form. Basically the range at which the solid changes its state into a liquid. •The melting point of water is 0 degrees Celsius
B. Four States of Matter • Liquids – particles can move around but are still close together – variable shape – fixed volume – Virtually incompressible
Boiling point
• • The boiling point of an element or compound means the temperature at which the liquid form of an element or compound is at equilibrium with the gaseous form. the boiling point of water is 100 degrees Celsius.
B. Four States of Matter • Gases – particles can separate and move throughout container – variable shape – variable volume – Easily compressed – Vapor = gaseous state of a substance that is a liquid or solid at room temperature
B. Four States of Matter • Plasma – particles collide with enough energy to break into charged particles (+/-) – gas-like, variable shape & volume – stars, fluorescent light bulbs, TV tubes
Physical properties • List as many physical properties as you can for this item
Chemical properties • A Chemical property is a characteristic of a substance that can only be observed by changing it into a different substance.
• http://app.discoveryeducation.com/techbook2:concept/view /guidConceptId/22cc81ed-8bd3-4b53-8964 18551be0242d/guidUnitId/1ef90b7b-c4ee-40d5-bcdc ff4f708f8873#/tab=explore-tab&page=1&subTab=session5
Chemical properties - Examples • Examples of chemical properties include: – The ability to burn – Ability to tarnish – Ability to rust – – Ability to decompose Ability to react with other chemicals – Instability – Ability to do acid/base reactions
Chemical properties • List as many chemical properties as you can for this item.
• • Chemical and physical properties – So what?
Titanium is very strong and doesn ’ t rust, so it is often used in jet engines.
Titanium is also nonallergenic. This, combined with the fact that it is rust proof makes it great for artificial joints as well as piercings.
• • Chemical and physical properties – So what?
Tungsten is usually used as the filament in lightbulbs because it has the highest melting point of any metal.
It glows red hot when electricity runs through it, and it gives off both heat and light.
• Chemical and physical properties – So what?
Vanadium is heavier and harder than titanium, so mixing a tiny bit of vanadium with steel can make cheap tools that are still very strong.
• • • Chemical and physical properties – So what?
Helium is almost completely nonreactive (inert).
It is lighter than air, so it ’ s great for floating balloons (or making funny voices.) When electricity runs through helium, it glows a creamy pale peach color.
• Chemical and physical properties – So what?
In 1943, all US pennies were made of zinc plated steel because copper was being used in the war. The pennies had to be coated with zinc because steel will rust, but zinc won ’ t.
• • Chemical and physical properties – So what?
Sulfur smells awful. Rotten eggs, onions, and garlic all have sulfur in them. Stink bombs use sulfur to create a bad smell.
Sulfur is also flammable, and it is one of the 3 main ingredients in gun powder.
• Chemical and physical properties – So what?
Chromium is famous for its intense luster. Chrome plated tools, jewlery, silverware, or car parts are very popular.
• Chemical and physical properties – So what?
Most bullets are made of lead because lead is a very dense metal. These bullets are required, by international law, to be coated with a different metal because lead has such a low melting point and is so malleable.
• Chemical and physical properties – So what?
The most dense elements are Iridium and osmium which have a density of about 22.6 g/cm3
Element abundance • • • The most common element in the universe is Hydrogen (about 75%), and Helium (about 25%).
The most common element on Earth is Oxygen (46.6%), and Silicon (27.7%).
The most common element in your body is Oxygen (65%), and Carbon (18%)
Physical or Chemical Property?
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Ability of gun powder and fire to explode.
Chemical Property
Physical or Chemical Property?
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The color of a sunset.
Physical Property
Physical or Chemical Property?
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The ability of a nail to rust.
Chemical Property
Physical or Chemical Property?
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The shape of a leaf.
Physical Property
Physical or Chemical Property?
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The ability of wood to burn.
Chemical Property
Physical or Chemical Property?
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The hardness of a diamond.
Physical Property
Physical or Chemical Property?
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The volume of your coke.
Physical Property
Physical or Chemical Property?
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The mass of two camels. Physical Property
Chemical and physical changes
Physical Change • A Physical change is a change in a substance that does not change what the substance is.
Physical Changes
• •
a change that occurs without identity changing the of the substance.
____ new substances are formed.
No
Examples of Physical Changes
• • • • • •
Change in size, shape, or color Pencil shavings Torn Paper Crushed ice Sugar dissolved in water Painting a wall
Physical Change - examples • Examples of physical change include: – Change in shape – Change in size – • • • • Change in phase • • • Melting (solid to liquid) Boiling (liquid to gas) Evaporation (liquid to gas) Condensation (gas to liquid) Freezing (liquid to solid) Sublimation (solid to gas) Deposition (gas to solid)
Physical Change • Physical changes might be caused by: – Grinding – Cutting – Crushing – – Bending Breaking – Heating/cooling • (change in phase) – squishing
Physical Change •
Evidence that a physical change has
occurred might include: – Change in shape – Change in form – Change in size – Change in phase (This is always a physical change!) – Physical changes are usually reversible
Physical change • What could you do to these items to cause a physical change to occur?
Chemical change • A chemical change is a change in which a substance is changed into a different substance. (You ’ ve changed what it is.)
Chemical Changes
•
a change that occurs that causes identity change; something is formed.
the new
•
New substances with properties are formed new
Evidence of Chemical Change
•
New ________appears
•
Bubbbles or ________
•
Precipitate forms (____ material)
• • •
_____ is produced ______ is produced ______ is given off
•
Difficult or impossible to __________
Chemical Change: Evidence •
Evidence that a chemical change has occurred might include:
– A color change – An odor change – Formation of a precipitate (you mix two liquids and make a solid) – Gas is formed (bubbles) – Changes in physical properties.
• Chemical change Examples of chemical changes include: – Burning – Rusting – Tarnishing – – Decomposing Polymerization
Chemical change • Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form.
Reactions with Acid
•
Vinegar + baking soda = release of Carbon Dioxide Gas
Reactions with Oxygen
•
OXIDATION
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Iron + Oxygen = rust
Reactions with Electricity
•
Silver Plating
Reactions between Substances
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Sodium + chloride = salt
•
Silver + sulfer in the air = tarnish
Other Examples
• • • • •
Wood burning Metal rusting Food digesting Gasoline burning Cake baking
Physical and Chemical change • During a chemical change energy can be released in the form of: – Heat – Light
• Chemical change – Chemical reactions When a chemical change occurs, energy is either released or absorbed.
• Physical and Chemical change heat A chemical reaction that releases energy in the form of heat is called
exothermic.
– Heat comes OUT • • Exo = out Thermic = heat – It will feel HOT.
• Physical and Chemical change heat A chemical reaction that absorbs energy in the form of heat is called
endothermic.
– Heat goes IN • • Endo = in Thermic = heat – It will feel COLD
Physical or Chemical Change?
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Water evaporates from the ocean.
Physical or Chemical Change?
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The yolk of an egg, which contains sulfur, causes tarnish to form on silver.
Physical or Chemical Change?
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The ice on a lake melts to become water in the lake.
Physical or Chemical Change?
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Charcoal in a fire turns to ash after several hours.
Physical or Chemical Change?
•
A pencil is sharpened in a pencil sharpener, leaving behind shavings.
Physical or Chemical Change?
•
A battery makes electricity to turn on a flashlight.
Physical or Chemical Change?
•
A bicycle rusts when left in the rain.
Physical or Chemical Change?
•
A shirt is accidentally torn in the washing machine.
Physical or Chemical Change?
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A log is split in two by an axe.
Quiz time!
• • Which life cycle is most similar to a chemical change?
Why?
Grasshopper = Egg nymph adult Butterfly = egg larva pupa adult
Quiz time!
• • What type of reaction is most likely occurring here? How do you know?
Quiz time!
• • What type of reaction is most likely occurring here? How do you know?
Quiz time!
• • What type of reaction is most likely occurring here? How do you know?