Chapter 3 States of Matter

Section 3.1 Solids, Liquids, and Gases Describing the States of Matter Is water a solid a liquid or a gas? That was easy but can you tell me how you know this? Materials can be classified as solids, liquids or gases based on whether their shapes or volumes are definite or variable.

Section 3.1 Solids, Liquids, and Gases Describing the States of Matter (cont) What is an objects shape? An objects shape is its definite or distinctive form. What is an objects volume? An objects volume is the amount of space occupied by its three dimensional form.

Section 3.1 Solids, Liquids, and Gases A solid is the state of matter that has a definite shape and volume. Give three examples of solids: 1.) Your pencil 2.) Your science book 3.) Your desk

Section 3.1 Solids, Liquids, and Gases Solids (cont) The term definite means that when you change the surroundings or container you are carrying the material in it does not change its shape. The term definite DOES NOT mean that the shape can never change…Does the shape of your pencil change when you sharpen it?

Section 3.1 Solids, Liquids, and Gases Solids (cont) The atoms that make up a solid are tightly packed and have a regular arrangement.

Section 3.1 Solids, Liquids, and Gases A liquid is the state of matter that has a definite volume but not a definite shape. Give three examples of liquids: 1.) milk 2.) water 3.) gasoline

Section 3.1 Solids, Liquids, and Gases Liquids (cont) A liquid DOES NOT have a definite shape because it forms to the container it is held in. A liquid has a definite volume…If you pour a 2 liter bottle of soda into glasses is there still 2 liters?

Section 3.1 Solids, Liquids, and Gases Liquid (cont) The atoms that make up a liquid are still close together but they have a more random layout.

Section 3.1 Solids, Liquids, and Gases A gas is the state of matter that does not have a definite shape or a definite volume. Give three examples of gases: 1.) Oxygen 2.) Carbon Dioxide 3.) Steam

Section 3.1 Solids, Liquids, and Gases Gases (cont) A gas DOES NOT have a definite shape…think about blowing up a balloon, Does every balloon have the same shape? A gas DOES NOT have a definite volume…What happens to a balloon if you leave it outside in the car on a cold night?

Section 3.1 Solids, Liquids, and Gases Gases (cont) The atoms of a gas very spread out and lack any type of definite shape.

Section 3.1 Solids, Liquids, and Gases Other States of Matter Solids, liquids and gases are the three most common forms of matter here on Earth. 99.9% of matter in outer space exists in stars like our sun as an extremely hot state known as plasma. At extremely low temperatures there is a state of matter that contains many particles that act as one, it is known as Bose-Einstein condensate.

Section 3.1 Solids, Liquids, and Gases Kinetic Theory Why do materials exist in different states of matter under the same conditions? To answer this question we must first look at kinetic energy, or the amount of energy an object has due to its motion.

Section 3.1 Solids, Liquids, and Gases Kinetic Theory (cont) The faster an object moves the greater its kinetic energy. A major league fastball has more kinetic energy then a pitch thrown by a little league pitcher. The kinetic theory of matter says that all particles of matter are in constant motion.

Section 3.1 Solids, Liquids, and Gases Explaining the Behavior of Gases The motion of gas particles can be compared to the motion of billiard balls in a game of pool. When one ball strikes another the first ball slows and the second begins to move…the kinetic energy is transferred. The same thing happens to gas particles.

Section 3.1 Solids, Liquids, and Gases Motion in Gases Unlike billiard balls gas particles are never at rest!!! There are forces of attraction among the particles in all matter. This attraction in gas is very weak…this is why the particles are so far apart and have such an erratic layout.

Section 3.1 Solids, Liquids, and Gases Kinetic Theory of Gases The constant motion of particles in a gas allows a gas to fill a container of any shape or size. This theory is applied to gases to form three points: 1.) Particles in a gas are in constant random motion. * This means the particles are always moving with no pattern

Section 3.1 Solids, Liquids, and Gases Kinetic Theory of Gases 2.) The motion of one particle is unaffected by the motion of another unless they collide. * This means that unless they run into each other they don’t affect each other. 3.) Forces of attraction for gases under normal conditions can be ignored. * This means the attraction is weak and has no effect

Section 3.1 Solids, Liquids, and Gases Explaining the Behavior of Liquids The attractive force in liquids is a bit stronger then that in gases. Liquids can flow to fit any container because the attraction is not super strong…but the force is strong enough to keep a liquids density constant.

Section 3.1 Solids, Liquids, and Gases Explaining the Behavior of Solids The attractive force between particles in a solid is very strong. The shape and volume are constant. The particles still move…they vibrate in place.

3.2 The Gas Laws Pressure Pressure is the result of a force distributed over an area. Example: A hockey puck hits the glass surrounding the rink…the force of the small puck hitting a large piece of glass results in a pressure.

3.2 The Gas Laws Pressure The SI unit for pressure is the pascal (Pa). One pascal is a very small amount of pressure, so when scientists want to talk about a large amount of pressure they measure it in kilopascals (kPa).

3.2 The Gas Laws Pressure (cont) Collisions between particles of a gas and the walls of the container cause pressure in a closed container of gas.

3.2 The Gas Laws Factors That Affect Gas Pressure Three factors affect the pressure of a gas: 1.) Temperature 2.) Volume 3.) Number of Particles

3.2 The Gas Laws Temperature Raising the temperature of a gas will cause the gas particles to expand…this is because the introduction of heat causes the kinetic energy to rise. Lowering the temperature of a gas will cause the gas particles to contract…for the opposite reason as above.

3.2 The Gas Laws Volume Reducing the volume of a gas increases the pressure if the temperature and number of particles is constant. Think about breathing…when you breath in you are relaxing your diaphragm and allowing more room for your lungs to fill up.

3.2 The Gas Laws Number of Particles Increasing the number of particles will increase the pressure if the volume and temperature stay the same. Think about a balloon…if you blow up a balloon there is a point that it can NOT gain any more volume and if you keep blowing it up the pressure builds up until it pops.

3.2 The Gas Laws Charles’s Law Jacques Charles, a French physicist, investigated the relationship between temperature and pressure in gases. He determined that at -273.15°C or 0K the pressure of a gas will become zero, this is known as absolute zero.

3.2 The Gas Laws Charles’s Law (cont) Charles’s Law states that the temperature and pressure of a gas are directly proportional assuming the volume and number of particles stays constant. V1 = V2 T1 T2

3.2 The Gas Laws Boyle’s Law Robert Boyle, an Irish scientist, is famous for investigating the relationship between the pressure and the volume of a gas. Boyle’s law states the pressure of a gas is inversely proportional to its volume if the temperature and number of particles remains constant. P1V1 = P2V2

3.2 The Gas Laws Combined Gas Law A single gas law can be used to describe both of these gas laws: P1V1 = P2V2 T1 T2

3.3 Phase Changes Characteristics of Phase Changes The states of matter for the same substance can change. This is why they are also called phases. Think about water, ice and steam!!!

3.3 Phase Changes Characteristics of Phase Changes (cont) A phase change is the reversible physical change that occurs when a substance changes from one state of matter to another.

3.3 Phase Changes Temperature and Phase Changes When a phase change occurs the temperature of the substance does not change. Example: Naphthalene is a compound used in moth balls…when it is heated the temperature of the naphthalene will rise until it hits 80°C and it will remain there until all of it has all melted.

3.3 Phase Changes Energy and Phase Changes Energy is either absorbed or released in a phase change. An endothermic change is when energy is absorbed…ice absorbs heat causing it to melt. An exothermic change is when energy is released…water releases heat to turn to steam.

3.3 Phase Changes Melting and Freezing The arrangements of the particles of a substance become less orderly when something melts and more orderly when it freezes. Think about the states of matter associated with melting and freezing.

3.3 Phase Changes Melting and Freezing (cont) Melting is the addition of energy allowing for the particles to move more rapidly. Freezing is the removal of energy causing the particles to slow down.

3.3 Phase Changes Vaporization and Condensation When a liquid changes phases to a gas it is called vaporization. Vaporization is endothermic…meaning energy must be taken in. The heat of vaporization is the amount of energy a substance needs to change from a liquid to a gas.

3.3 Phase Changes Vaporization and Condensation (cont) Evaporation takes place at a temperature below boiling point…it takes place at the surface. After it rains on a hot day in the summer the rain water will evaporate…Is it 100°C when this happens? NO The vapor pressure is the pressure that builds due to the increased collisions between the gas and the container.

3.3 Phase Changes Vaporization and Condensation (cont) A liquid boils when the vapor pressure equals the pressure of the atmosphere…the gases release in the form of bubbles.

3.3 Phase Changes Vaporization and Condensation (cont) Condensation is the process of a gas changing phases to a liquid. This is the process responsible for morning dew!!!

3.3 Phase Changes Sublimation and Deposition Sublimation is the process of a solid turns directly into a gas. Example: Dry Ice is solid Carbon Dioxide…at room temp it turns into a gas. Deposition is the process of a gas turning directly into a solid. Example: When ice forms on your parents windshields in the winter it is water vapor turning into a solid.