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Physical Science Chapter 16
Solids, Liquids, Gases, and Plasma
1
The Big Idea Many physical
properties of matter can be described by the motion of the particles.
The states of matter are:
§ Solid § Liquid § Gas § Plasma
Objectives: Describe and illustrate the physical differences among solids, liquids, and gases in terms of their mass, volume, density, shape and particle arrangement. Understand that at the phase change of water there is virtually no change in temperature.
16:1 Kinetic Theory
Matter is made of particles-atoms or molecules in continual motion. Particles exert electrical forces on each other that depend upon the distance these particles are from each other. As particles become farther apart the less strength the force is between them. In solids and liquids the distance between particles is about 10-10 m apart. In gases, the distance is typically 1000 times greater. Nothing between these particles.
Particles in Matter
16:1 Kinetic Theory
Did you know that steam is NOT water in the gaseous state? It is liquid water droplets that has condensed from gaseous water in the air.
Extra Credit Assignment: (Up to 10 pts to lowest grade to date)
Preserving a Solid State Question: How would you pack and transport a
fragile chocolate sculpture that must be shipped to a warm, tropical climate?
Design a package to keep chocolate from melting, breaking and getting wet. The sculpture must arrive in 3 days. The packaging and shipping should be moderately priced and affordable for a manufacturer and customer.
You must draw your design and supply estimated costs for shipping. You have 1 week to complete.
16:1 Kinetic Theory
A. States of matter are solid, liquid, gas, and plasma.
1. The kinetic theory explains how particles in matter behave.
16:1 Kinetic Theory
• The three assumptions of the kinetic theory are as follows:
a. All matter is composed of small particles.
b. Particles are in constant, random motion.
c. Particles collide with each other and walls of their containers
16:1 Kinetic Theory
2. Thermal energy—total energy of a material’s particles; causes particles to vibrate in place.
16:1 Kinetic Theory
3. Average kinetic energy—temperature of the substance, or how fast the particles are moving; the lower the temperature, the slower the particle motion.
16:1 Thermal Energy
4. Solid state—particles are closely packed together in a specific type of geometric arrangement.
• This attraction between the particles gives solids a definite shape and volume. However, the thermal energy in the particles causes them to vibrate in place.
16:1 Kinetic Theory
• Thermal energy is the total energy of a material’s particles including: • kinetic—vibrations and
movement within and between the particles
• potential—stored energy..
16:1 Average Kinetic Energy
• In science, temperature means the average kinetic energy of particles in the substance, or how fast the particles are moving.
Add this to your notes.
16:1 Average Kinetic Energy
• Molecules will have kinetic energy at all temperatures, including absolute zero.
Add this to your notes.
Liquid State
• What happens to a solid when thermal energy or heat is added to it?
5. Liquid state—a solid begins to liquefy at the melting point as the particles gain enough energy to overcome their ordered arrangement.
a. Energy required to reach the melting point is called the heat of fusion.
Liquid State
b. Liquid particles have more space between them allowing them to flow and take the shape of their container.
Gas State
6. Gaseous state—a liquid’s particles have enough energy to escape the attractive forces of the other particles in the liquid.
Gases do not have a fixed volume or shape.
• Therefore, they can spread far apart or contract to fill the container that they are in.
Gas State
a. Heat of vaporization is the energy required for a liquid to change to a gas.
b. At the boiling point, the pressure of the liquid’s vapor is equal to the pressure of the atmosphere and that liquid becomes a gas.
Gas State
c. Gas particles spread evenly throughout their container in the process of diffusion.
7. Heating curve of a liquid—as a solid melts and a liquid vaporizes, the temperature remains constant; the temperature will increase after the attractive forces of the earlier state are overcome.
Heating Curve of a Liquid
• This type of graph is called a heating curve because it shows the temperature change of water as thermal energy, or heat, is added.
• Notice the two areas on the graph where the temperature does not change.
• At 0°C, ice is melting.
Heating Curve of a Liquid
The temperature remains constant during melting.
• After the attractive forces are overcome, particles move more freely and their average kinetic energy, or temperature, increases.
Gas State
• The boiling point of a liquid is the temperature at which the pressure of the vapor in the liquid is equal to the external pressure acting on the surface of the liquid.
• Unlike evaporation, boiling occurs throughout a liquid at a specific temperature depending on the pressure on the surface of the liquid.
Even though gases fill the volume of their container, almost all of the volume of the container is empty space. The volume of a container of gas is much greater than the total volume of the gas particles.
Plasma State
7. Plasma—state of matter consisting of high-temperature gas with balanced positively and negatively charged particles.
Fun Fact: unlike most gases, plasmas conduct electricity well and are affected by magnetic fields. Also, while the particles that make up gases move randomly, sometimes the electrons and ions that make up plasmas move together in a wavelike motion.
Plasma State
• All of the observed stars including the Sun consist of plasma. Plasma also is found in lightning bolts, neon and fluorescent tubes, and auroras.
Plasma State
Scientists estimate that about 99% of all matter in the universe is plasma.
• Although this matter contains positive and negative particles, its overall charge is neutral because equal numbers of both charges are present.
Expansion of Matter
• Particles move faster and separate as the temperature rises. This separation of particles results in an expansion of the entire object, known as thermal expansion.
8. Thermal expansion is an increase in the size of a substance when the temperature is increased.
Thermal Expansion
The separation lines in concrete are called expansion joints.
• Have you noticed the seams in a concrete driveway or sidewalk?
Thermal Expansion
• When concrete absorbs heat, it expands. Then when it cools, it contracts.
• If expansion joints are not used, the concrete will crack when the temperature changes.
Thermal Expansion • Sealing food containers is important to
preserve freshness and prevent spoilage. What are two reasons a lid put on food container when it is warm might become tight as the food cools?
• Inside the container, warm gases gradually cool, causing the pressure inside the container to drop. Then the pressure outside the container is greater than the pressure inside the container, and the lid has a tighter seal. Also, when the lid placed on the warm container begins to cool, it contracts slightly, causing it to fit more tightly on the container.
Expansion in Liquids
• The particles in the liquid in the narrow thermometer tube start to move farther apart as their motion increases.
b. The size of a substance will decrease when the temperature decreases.
Expansion in Liquids
• The liquid has to expand only slightly to show a large change on the temperature scale.
c. Expansion and contraction occur in most all solids, liquids and gases.
Expansion in Gases
• This expansion results in a decreased density of the hot air. Because the density of the air in the hot-air balloon is lower than the density of the cooler air outside, the balloon will rise.
d. Water is an exception to the expansion rule because it expands as it becomes a solid.
The Strange Behavior of Water
• Water molecules are unusual in that they have highly positive and highly negative areas.
• These charged regions affect the behavior of water.
• As temperature of water drops, the particles move closer together.
16:1 Thermal Expansion
9. Some substances do not react as expected when changing states.
a. Amorphous solids—lack the tightly ordered structure found in crystals. Amorphous solids do not have definite temperature at which they change from solid to liquid.
16:1 Thermal Expansion
Examples of amorphous solids are glass, plastic.
b. Liquid crystals do not lose their ordered arrangement completely upon melting; used in liquid crystal displays in watches, clocks, calculators and some notebook computers.
End Section 1..
Section 2:
Properties of Fluids Objectives: § I will be able to explain Archimedes’ principle. § I will understand the concept of buoyancy and
density and how this applies to life situations. § I will make qualitative and quantitative
observations. Vocabulary: Review: qualitative & quantitative observations, density
New: buoyancy, fluid
Section 2: Properties of Fluids
An object will float in a fluid if the buoyant force exerted by a fluid is equal to the object’s weight.
Why Things Float
Section 16-2 Properties of Fluids
1. Buoyancy —ability of a fluid (liquid or gas) to exert an upward force on an object immersed in it.
Section 16-2 Properties of Fluids
a. An object in a fluid will float if its weight is less than the buoyant force acting on it from the fluid.
Section 16-2 Properties of Fluids
b. An object in a fluid will sink if its weight is more than the buoyant force acting on it from the fluid.
16:2 Archimedes’ Principle
Archimedes was a Greek mathematician who lived during the 3rd century and made an important discovery about buoyancy.
Archimedes Video 3:00
Section 16-2 Properties of Fluids
2. Archimedes’ Principles states that the buoyant force on an object is equal to the weight of the fluid displaced by the object.
Section 16-2 Properties of Fluids
a. An object will float if its density is less than the density of the fluid it is placed in.
b. Density is mass per unit volume.
16:2 Properties of Fluids
Do you know why ships float? What keeps them from sinking? Some ships weigh tons. How can something that heavy float? The Diamond Princess Ship weighs 113,000 tons, 951 feet long, can carry 3100 passengers and has 15 decks. Imagine the total weight of such a ship.
Sink, Float, Hover Design a Submarine
• You will work within a group of 3-4 people. • The group will record information and then
discuss it when the group is finished with the activity.
• Draw a picture of your submarine while it is • Floating • Sunk • Hovering
• Beside the drawing on your observation sheet you will make a qualitative and a quantitative observation.
Sink, Float, Hover Design a Submarine
1. What did you do to get the sub to float? 2. What did you do to make the sub sink? 3. What did you do (or try to do) to make it
hover? 4. What is similar about the subs that float? 5. What is the downward force on the sub? 6. What is the upward force on the sub? 7. Which of the 3 challenges was most difficult?
Why?
Section 2:
Properties of Fluids Objectives: Can you discuss these intelligently? § I can explain Archimedes’ principle. § I do understand and can explain the concept of
buoyancy and how it applies to life situations. § I can make qualitative and quantitative
observations.
Your assignment is to complete the Data and Observation Sheet and submit it next class.
16:2 Pascal’s Principle 3. Pascal’s principle—pressure applied to a fluid is transmitted throughout the fluid. a. Pressure is force exerted per unit area. b. Hydraulic machines use this principle to lift heavy objects.
16:2 Bernoulli’s Principle David Bernoulli was a Swiss scientist who studied the properties of moving fluids such as water and air.
4. Bernoulli’s principle states that as the velocity of a fluid increases, the pressure exerted by the fluid decreases. Airplanes use this principle to fly.
Video Video 2
16:2 Bernoulli’s Principle An airplane wing is curved. As the plane moves forward, the air passing over the top of the wing travels faster than the air passing below it. Thus, the pressure above the wing is less than the pressure below it. This results in a net upward force on the wing. This upward force contributes to the lift of an airplane wing.
Bernoulli’s Principle
Where there is moving air, there
is low pressure. Bernoulli’s Principle Video
16:2 Fluid Flow Another property exhibited by fluid is its tendency to flow.
5. Viscosity is a liquid’s resistance to flow. a. Molecular structure determines a fluid’s viscosity. Fluids vary in their tendency to flow. Cold syrup doesn’t want to flow as easily as water. The syrup’s viscosity is high because it flows slowly.
b. Increased temperature will lower the viscosity. End Section 2
Section 3: Behavior of Gases
The pressure, volume and temperature of a gas are each affected by the other two properties.
16:3 Behavior of Gases Without gravitational forces, the air we breathe would float off into space. Gases tend to take the shape of the container that holds them. Our atmosphere is held in place by the gravitational force on the tiny gas particles.
16:3 Pressure
Gravity exerts pressure downward toward the center of the earth. 1. Pressure is the amount of force exerted per unit of area. a. Pressure is measured in units called pascal (Pa).
16:3 Particle Collisions
Gas particles are constantly moving and colliding with anything in their path. b. The collisions of particles of gas in the air result in atmospheric pressure.
Gas Particles colliding produce a pressure.
2. Moving particles colliding with the inside walls of a container result in gas pressure.
16:3 Particle Collisions
3. Boyle’s Law relates pressure and volume.
a. Volume decreases as pressure increases.
b. Pressure decreases as volume increases.
16:3 Particle Collisions
c. Pressure multiplied by volume is always equal to a constant if the temperature is constant.
16:3 Particle Collisions
4. Pressure is the amount of force exerted per unit of area, or P=F/A. (P is pressure, F is force and A is area.) Pressure is measured in pascals (Pa), the SI unit of pressure.
16:3 Particle Collisions
Because pressure is the amount of force divided by area, one pascal of pressure is one Newton per square meter or 1 N/m2.
16:3 Particle Collisions
5. If a substance has mass and energy it will move. 6. Electrolysis is used to remove the hydrogen and oxygen from water.
16:3 Particle Collisions
Often gases are held within containers. Balloons and bicycle tires are considered
containers. They remain inflated because of collisions air particles have with the walls of their containers.
16:3 Temperature-Pressure Law
On aerosol cans there is a warning “keep away from heat.” Do you know why?
16:3 Charles’ Law 7. Charles’ Law relates volume and temperature. a. At a constant pressure, volume increases as temperature increases. b. At a constant pressure, volume decreases as temperature decreases.
End. 16.3 math
Review for Test States of Matter 20
Review for Test
§ Test coming soon. § Notebook due.
