Transcript CHEMISTRY – “Particles” - Mr. Jones's Science Class
Matter
Matter
• Anything that has mass and takes up space (volume) – Examples:
• A brick has mass and takes up space • A desk has mass and takes up space • A pencil has mass and takes up space • Air has mass and takes up space All of the above examples are considered matter because they have mass and take up space. Can you think of anything that would not be considered matter?
Physical Properties of Matter
• any property of matter that can be observed or measured without changing the identity of the matter • Examples
color shape taste
D = m V
Chemical Properties of Matter
• any property of matter that describes a substance based on its ability to change into a new substance • Examples
flammability reactivity with vinegar reactivity with oxygen
Iron + Oxygen
2Fe + 3O 2
Iron oxide (rust)
Fe 2 O 3
Chemical or Physical Property?
2.
1.
Paper is white
Physical Property
Boiling point of H 2 O is 100 o C
Physical Property
3.
5.
4.
Chemical Property
Nitrogen does not burn
Chemical Property
Sulfur smells like rotten eggs
Physical Property
Comparing Physical and Chemical Properties
Substance/Matter Physical Property Chemical Property Helium Wood Baking soda Powdered sugar Rubbing alcohol Red food coloring Iron Less dense than air Grainy texture White powder White powder Clear liquid Red color Malleable Nonflammable Flammable Reacts with vinegar to produce bubbles Does not react with vinegar Flammable Reacts with bleach and loses color Reacts with oxygen
Physical Change
• a change in shape, size, color, or state • a change without a change in chemical composition • a change that is reversible – The Mixtures Lab • Examples
tearing paper cutting your hair change in state
Changes in States
(Physical Changes)
Ionization
Plasma
Melting
Bose-Einstein
Disposition Recombination Vaporization
(Evaporation/Boiling)
Liquid Solid Gas
Condensation Freezing Sublimation
All changes in state require a change in energy
Phase Changes Simulation • PhET • Harcourt School • Pearson
This is what happens when energy is added and/or taken away from matter
Chemical Change
• a change in which a substance becomes another • a change that is not reversible using ordinary physical means • Changes that usually cause heat, sound, light, odor, fizzing/foaming, color changes
You usually need more than one of the above characteristics to be considered a chemical change!
• Examples
combining sulfuric acid and sugar burning a piece of wood soured milk
5.
Chemical or Physical Change?
3.
1.
2.
Bending a Paper Clip
Physical Change
Baking a cake
Chemical Change
The sublimation of carbon dioxide 4.
Physical Change
Crushing an aluminum can
Physical Change Chemical Change
Mass vs. Weight
Mass Weight • a measure of how much matter an object is made of • does not change, regardless of where something or someone is • the force of gravity on an object • equal to the mass of the body times the local acceleration of gravity Why do you think the person’s weight is less on the moon?
Mass = 59 kg Weight = 579 N Mass = 59 kg Weight = 96 N http://www.exploratorium.edu/ronh/weight/index.html
5 Physical States of Matter • Bose-Einstein
(Newest State)
• Solid • Liquid • Gas • Plasma
Bose-Einstein Condensate
• Exist at extremely (around absolute zero or -460 o F) • Particles are super unexcited • Particles lock or “clump” together so firmly that they move as a single unit • Definite shape and volume (?)
Solid
• Particles are tightly compact • Particles vibrate without the ability to move freely • Definite shape and volume • Solid Animation
Liquid
• Particles are tightly compact, but able to move around close to each other • No definite shape, but definite volume • Liquid Animation
Gas
• Particles can easily spread out or move close together • Particle move freely and with a lot of energy • No definite shape or volume • Gas Simulation
Plasma
• Exist at extremely high million degrees Celsius) • Particles are broken apart • Particles move freely and with extremely high energy on Earth, however it is the matter in the universe • No definite shape or volume (?) neon lights, lightning, aurora Why do you think this is the most common form/state of matter in the universe?
Energy and the States of Matter
• The physical states of matter result from the amount of energy the particles composing the matter have. Basically, more energy means more movement for the particles and less energy means less movement. • Energy/Temperature and Matter Simulations – PhET – BEC: Temperature and Absolute Zero If you were to compare an ice cube and the steam created from boiling water, which would you think has more energy?
States of Matter Continuum
What about this continuum could be considered a little misleading? Taken from: http://www.chem4kids.com/files/matter_becondensate.html
Density
• a measure of the amount of matter present in a • typically expressed in the following units: – grams per cubic centimeter (g/cm 3 ) for solids – grams per milliliter (g/ml) for liquids • does not depend on how much of a substance you have (intrinsic property) – in other words, the density of a gold bar would be the same as the density of a gold flake • can change as temperature and pressure change Which do you think is more dense? Why?
Layering Liquids
Using a test-tube and the eyedroppers, try to layer the four different colored liquids so that the colors don’t mix and show distinct layers.
1. Hold the test-tube in your hand at a 45 degree angle.
2. Using the eyedropper from one of the colors, slowly place the liquid into the test-tube.
3. Repeat step two using the other three liquids until you get them layered. Record the order of the colors.
If you don’t get clear separation of the colors, you should empty the contents of the test tube down the drain and start again. These steps may need to be repeated several times until you discover the correct order of the colors.
*Placing white paper behind the straws will help you see the divisions
Layering Liquids - Discussion
1. Were you capable of layering the four liquids? bottom up?
2. What difficulties did you experience when performing this activity?
3. Why do you think the liquids created layers when putting them in the test tube in the correct order?
4. Because these liquids are miscible, or partially miscible, they did not really create distinct layers. What do you think it means to be miscible?
Calculating Density
• Density can be calculated by dividing the mass of an object by its volume D = m V Sample Problem Timothy found a solid metal block that has a mass of 100 grams and a volume of 25 cm 3 . What would be the density of the block? 4 grams cm 3
Practice Problems
1. Find the density of a substance with a mass of 27 g and a volume of 7 cm 3 .
D = m V D = 27 g 7 cm 3 = 3.86 grams cm 3 2. A block of maple has a mass of 20 grams and a volume of 26.5 cm 3 . What is the density of the block?
D = m V D = 20 grams 26.5 cm 3 = 0.75 grams cm 3