Solids, Liquids, and Gases Chapter 16 Section 1 Kinetic Theory

Solids, Liquids, and Gases Section 1 Kinetic theory slides 3-47 Section 2 Properties of Fluids slides 50-64 Section 3 Behavior of Gases slides 65-80

1 Kinetic Theory of Matter How particles move in the four states of matter How particles behave at the melting point and boiling points

Kinetic Theory Explains how particles of matter behave using three basic assumptions: 1) All matter is composed of small particles- atoms, molecules and ions.

Kinetic Theory Explains how particles of matter behave using three basic assumptions: 1) All matter is composed of small particles- atoms, molecules and ions. 2) These particles are in constant motion. The motion has no pattern.

Kinetic Theory Explains how particles of matter behave using three basic assumptions: 1) All matter is composed of small particles- atoms, molecules and ions. 2) These particles are in constant motion. The motion has no pattern. 3) These particles are colliding or crashing into each other and into the walls of the container.

Thermal Energy Thermal energy is the total energy of the particles in a material including both potential and kinetic. When the temperature is lowered, its particles will have less TE and will vibrate more slowly.

Average Kinetic Energy Temperature is the average KE of particles in a substance. The molecules in a solid randomly vibrate with temperature a measure of their average kinetic energy.

Average Kinetic Energy                                                 Temperature is the average KE of particles in a substance. The molecules in a solid randomly vibrate with temperature a measure of their average kinetic energy.

How do solids become liquids? Melting point is the temperature at which a solid begins to turn into a liquid.

How do solids become liquids? Melting point is the temperature at which a solid begins to turn into a liquid. Energy is needed for the particles in a solid to slip out of their ordered arrangement.

How do solids become liquids? Melting point is the temperature at which a solid begins to turn into a liquid. Energy is needed for the particles in a solid to slip out of their ordered arrangement. Heat of fusion is the amount of energy needed to change a substance from a solid to a liquid at its melting point.

Why do liquids flow?                                                 Particles in liquids have more KE allowing them to overcome their attraction and slide past each other more readily. This is why liquids flow and take the shape of their container; however, they still cling together and have a definite volume.

What is a gas state? Gas particles have enough KE to overcome the attractions among them so that they have no fixed volume or shape.

What is a gas state? Gas particles have enough KE to overcome the attractions among them so that they have no fixed volume or shape. They can spread far apart or move close together to fill a container.

What is a gas state? Gas particles have enough KE to overcome the attractions among them so that they have no fixed volume or shape. They can spread far apart or move close together to fill a container. If particles in a liquid move fast enough they can enter the gas state in a process called vaporization by evaporation or boiling.

How do liquids evaporate? Evaporation is vaporization that occurs at the surface of a liquid. It can occur below the liquid’s boiling point if particles at the surface have enough KE to escape liquid’s attractive force.

How does boiling vaporize liquids? Boiling occurs at a specific temperature which depends on the pressure on the surface of the liquid.

How does boiling vaporize liquids? Boiling occurs at a specific temperature which depends on the pressure on the surface of the liquid. Air exerts pressure on the surface of the liquid which keeps particles from escaping the liquid.

How does boiling vaporize liquids? 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 on the surface of the liquid.

How does boiling vaporize liquids? 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 on the surface of the liquid. Particles need energy to overcome the force of pressure.

How does boiling vaporize liquids? Heat of vaporization is the amount of energy needed for the liquid at its boiling point to become a gas.

Why do gases fill their containers? Gas particles move so quickly & are so far apart that they overcome the attractive forces among them; therefore, gases do not have a definite shape or a definite volume.

Why do gases fill their containers? Gas particles move so quickly & are so far apart that they overcome the attractive forces among them; therefore, gases do not have a definite shape or a definite volume. Diffusion is the spreading of particles throughout a given volume until they are evenly distributed.

What is the heating curve of a liquid?

What is the heating curve of a liquid? The graph slopes upward when the KE is rising. At B & D the graph is a horizontal line showing water temperature does not change.

What is the heating curve of a liquid? At what temp is the water turning into a gas?

What is the heating curve of a liquid? At 0°C, ice is melting.

What is the heating curve of a liquid? At 0°C, ice is melting. All of the energy put into ice at this temp is used to overcome the attractive forces among the particles in the solid.

What is the heating curve of a liquid? At 0°C, ice is melting. All of the energy put into ice at this temp is used to overcome the attractive forces among the particles in the solid. After melting, the particles move more freely and their temp begins to rise.

What is the heating curve of a liquid? At 100°C, water is boiling or vaporizing.

What is the heating curve of a liquid? At 100°C, water is boiling or vaporizing. The temperature stays the same again until the attractive forces are overcome.

What is the heating curve of a liquid? At 100°C, water is boiling or vaporizing. The temperature stays the same again until the attractive forces are overcome. Then energy returns to raising the temperatures of the particles.

What is the plasma state? Much of the matter in the universe is plasma, matter made up of positively and negatively charged particles with an overall neutral charge.

What is the plasma state? Much of the matter in the universe is plasma, matter made up of positively and negatively charged particles with an overall neutral charge. The faster they move, the greater the force when they collide causing atoms to rip off.

What is the plasma state? Much of the matter in the universe is plasma, matter made up of positively and negatively charged particles with an overall neutral charge. The faster they move, the greater the force when they collide causing atoms to rip off. Ex. Stars, lightning bolts, neon & fluorescent bulbs, and auroras.

Thermal Expansion Thermal expansion is an increase in the size of a substance when the temperature is increased. The kinetic theory explains both thermal expansion and contraction that occurs in most solids, liquids and gases.

How does expansion occur in solids? Expansion joints prevent concrete cracks when temperatures change.

How does expansion occur in liquids? One example of this occurs in a thermometer. The addition of energy makes particles in the liquid move farther apart.

How does expansion occur in gases? An example is a hot air balloon. Heating the air makes it expand and decreases the density making the balloon rise.

Why does water behave in different ways? Water expands when it freezes due to the negative and positive charges on it.

Why does water behave in different ways? Water expands when it freezes due to the negative and positive charges on it. Unlike charges attract each other. As the temp drops, the water particles move closer together lining up so that positive and negative areas are near each other leaving empty spaces in the structure.

Why does water behave in different ways? Water expands when it freezes due to the negative and positive charges on it. Unlike charges attract each other. As the temp drops, the water particles move closer together lining up so that positive and negative areas are near each other leaving empty spaces in the structure. Solid ice is less dense than liquid water.

Solid or Liquid? Not all materials have a definite temperature when they change from solid to liquid. Some get softer and slowly turn to liquid over a range of temperatures.

Solid or Liquid? Not all materials have a definite temperature when they change from solid to liquid. Some get softer and slowly turn to liquid over a range of temperatures. These amorphous solids, like glass & plastic, do not have the ordered structure of crystals.

Solid or a Liquid? Liquid crystals start to flow in the melting phase, but keep their ordered structure. Liquid crystals respond to temperature changes and electric fields. LCDs are used in watches and calculators.

Solid Liquid Gas Arrangement: Closely packed together Arrangement: Arrangement: Overcome attractions Behavior: Behavior: slip out of arrangement & flow Behavior:

Solid Liquid Gas Arrangement: Closely packed together Arrangement: Cling together with definite volume Arrangement: Overcome attractions Behavior: slip out of arrangement & flow Behavior: do not have definite shape or volume Behavior: Energy is needed for them to slip out of arrangement

2 Properties of Fluids Archimedes’ Principle Pascal’s Principle Bernoulli’s Principle

How do ships float? Buoyancy is a fluid’s ability to exert an upward force on an object in it.

How do ships float? Buoyancy is a fluid’s ability to exert an upward force on an object in it. Ships float because the force pushing up on the ship is greater than the force of the ship pushing down.

How do ships float? Buoyancy is a fluid’s ability to exert an upward force on an object in it. Ships float because the force pushing up on the ship is greater than the force of the ship pushing down. If the buoyant force is equal to the object’s weight, it floats; if the buoyant force is less than the object’s weight, the object sinks.

What is Archimedes’ principle? The buoyant force on an object is equal to the weight of the fluid displaced by the object. (displaced or “pushed away”)

What is Archimedes’ principle? The buoyant force on an object is equal to the weight of the fluid displaced by the object. (displaced or “pushed away”) A block of wood sinks until it displaces enough water to equal its weight, then it floats.

Do equal-sized objects float? Would a steel block the same size as the wood block float in water?

Do equal-sized objects float? Would a steel block the same size as the wood block float in water? The volume displaced for each block is equal; however, each block has a different mass & a different density

What does density have to do with buoyancy? If you formed the steel block into the shape of a boat filled with air, it will float. The density of the steel boat with air inside is less than the density of the water.

Pascal’s Principle Pressure is force exerted per unit area or P= E/A. Blaise Pascal (1623-1662), a French scientist, discovered a useful property of fluids. Pressure applied to a fluid is transmitted or sent throughout the fluid. Ex. Squeezing a toothpaste tube.

How is Pascal’s principle used? Hydraulic machines move heavy loads using Pascal’s principle. A fluid-filled pipe connects two cylinders. When pressure is applied to the smaller one, it is transferred to the larger one providing more force.

Bernoulli’s Principle Daniel Bernoulli, a Swiss scientist (1700-1782), discovered that as the velocity of a fluid increases, the pressure exerted by the fluid decreases.

Bernoulli’s Principle Engineers use this principle when designing aircraft wings and piping systems.

Fluid Flow Another property of a fluid is its tendency to flow. Viscosity , resistance to flow by a fluid, measures how much force is needed for one layer of fluid to flow over another layer.

Fluid Flow Another property of a fluid is its tendency to flow. Viscosity , resistance to flow by a fluid, measures how much force is needed for one layer of fluid to flow over another layer. Water has a low viscosity, but syrup has a high viscosity because it flows slowly.

3 Behavior of Gases How a gas exerts pressure on its container How changing pressure, temperature, or volume affect a gas

Pressure According to the kinetic theory, gas particles move constantly bumping into whatever is in their path. These collisions result in pressure or amount of force exerted per unit of area. Formula P = F/A Ex. Balloon, tire

How is pressure measured? SI Unit for pressure is pascal (pa) = one Newton per square meter or 1 N/m2.

How is pressure measured? SI Unit for pressure is pascal (pa) = one Newton per square meter or 1 N/m2. Because this is very small pressure unit, most pressures are given in kilopascals or kPa.

How is pressure measured? SI Unit for pressure is pascal (pa) = one Newton per square meter or 1 N/m2. Because this is very small pressure unit, most pressures are given in kilopascals or kPa. Atmospheric pressure at sea level = 101.3 kPa or about weight of large truck /square meter! (decreases with altitude)

Boyle’s Law If the container gets smaller, what happens to the pressure?

Boyle’s Law If the container gets smaller, what happens to the pressure? Robert Boyle, British scientist (1627-1691) If you decrease volume of a container of gas & keep the temperature the same, the pressure of the gas will increase. If you increase the volume & keep temp same, pressure will decrease.

Pressure outside an object affects volume Weather balloons carry instruments to high altitudes; as they rise they get bigger due to decrease in atmospheric pressure.

Using Boyle’s Law The pressure inside an object multiplied by its volume is always equal to the same number, or a constant, when the temperature stays the same. P1V1= constant = P2V2 If you know three values, you can find the unknown fourth value.

Using Boyle’s Law Use the equation P1V1 = P2V2. Assume that P1= 101 kPa and V1=10.0 L. If P2= 43.0 kPa , what is V2?

Using Boyle’s Law Use the equation P1V1 = P2V2. Assume that P1= 101 kPa and V1=10.0 L. If P2= 43.0 kPa , what is V2? 101 kPa · 10.0 L = 1010 kPaL 1010 kPaL/43.0 kPa = 24.5 L

The Pressure-Temperature Relationship Have you ever seen “keep away from heat” on a spray can? Why?

The Pressure-Temperature Relationship Have you ever seen “keep away from heat” on a spray can? Why? Heat causes the pressure to increase since the can is rigid & cannot increase in size until the pressure is too much and the can explodes. In low temps, decrease in pressure may cause the container to buckle.

Charles’s Law Jacques Charles, French scientist, 1746-1823, studied gases. Volume of gas increases with increasing temperature if pressure remains the same or volume decreases as temperature decreases.

Charles’s Law As gas is heated, its particles move faster & faster & its temperature increases. Instead of increased pressure the volume increases as it expands the container.

Charles’s Law Charles’s Law formula V1/T1= V2/T2 when pressure kept constant