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Chapter 3 Material on Midterm
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How do materials feel as they change state?
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Objectives ◦ Describe the properties shared by particles of all matter ◦ Describe three states of matter ◦ Explain the differences between the states of matter
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What are states of matter? ◦ The States of matter are the physical forms in which a substance can exist Solid Liquid Gas
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Particles of matter ◦ Matter is made of small particles called atoms and molecules ◦ Always on the move ◦ How they interact with each other determines their state of matter
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What is a solid? ◦ A solid is the state of matter that has a definite shape and volume ◦ Particles smooshed together ◦ Can only vibrate—stuck in place
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Types of solids ◦ Crystalline solids have a orderly, 3D arrangement in a repeating pattern Ice, diamond, iron ◦ Amorphous solids have no special arrangement Glass, rubber, wax
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What is a liquid? ◦ A liquid is the state of matter than has a definite volume but takes the shape of its container ◦ Little space in between particles ◦ Can slide past another
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Liquid characteristics ◦ Surface tension is a force that acts on the particles at the surface of a liquid ◦ Viscosity is a liquid’s resistance to flow
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What is a gas? ◦ A gas is the state of matter that has no definite shape or volume ◦ Molecules move super fast ◦ Not really held together at all
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Plasma is the most common state of matter in the universe (99%). It is a highly charged (ionized) gas. Present in stars. Bose-Einstein Condensate – at very low temperatures (near -273°C) atoms behave as though they were a single particle. Check it out
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State of MatterDefinite Shape?Definite Volume? Solid Liquid Gas
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Section Review ◦ Please answer the objectives on your objective summary sheet 1.Describe the properties shared by particles of all matter 2.Describe three states of matter 3.Explain the differences between the states of matter
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Objectives: ◦ Describe the three factors that affect how gases behave ◦ List the variables involved in Boyle’s law and Charles’s law ◦ Predict how a change in pressure or temperature will affect the volume of a gas
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What factors affect how gases behave? ◦ Temperature ◦ Volume ◦ Pressure
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Temperature Temperature ◦ Temperature is a measure of how fast the particles in an object are moving The faster the particles move, the more energy they have Increase temperature….increase pressure Increase temperatures…increase volume
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Volume ◦ Volume is the amount of space that an object takes up ◦ Volume of a gas depends on its container ◦ Decrease volume…increase pressure…pop! ◦ Increase volume…decrease pressure
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Pressure Pressure ◦ Pressure is the amount of force exerted on a given area of surface ◦ The more particles…the more pressure
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Gas behavior laws ◦ Boyle’s Law Involves volume and pressure ◦ Charles’s Law Involves temperature and volume
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Boyle’s Law
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What is Boyle’s Law? ◦ Boyle’s Law states that a fixed amount of gas at a constant temperature, the volume of a gas is inversely related to the pressure Inversely = opposite So… As pressure increases, volume decreases As pressure decreases, volume increases
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Charles’s Law
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What is Charles’s Law? ◦ Charles’s Law states that for a fixed amount of gas at a constant pressure, the volume of gas changes in the same way that the temperature changes ◦ So… As temperature increases, volume increases As temperature decreases, volume decreases
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Charles Law – soap Charles Law – soap Charles Law - Egg Charles Law - Egg
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Section Review ◦ Please answer the objectives on your objective summary sheet 1.Describe the three factors that affect how gases behave 2.List the variables involved in Boyle’s law and Charles’s law 3.Predict how a change in pressure or temperature will affect the volume of a gas
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Objectives ◦ Describe how energy is involved in changes of state ◦ Identify phase changes as endothermic or exothermic ◦ Describe what happens during melting and freezing ◦ Compare evaporation and condensation ◦ Explain what happens during sublimation and deposition ◦ Identify the two changes that can happen when a substances loses or gains energy ◦ Interpret a phase change(heating curve) diagram
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A change of state is the change of a substance from one physical form to another
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The six changes of state ◦ Melting (S L) ◦ Freezing (L S) ◦ Evaporation (L G) ◦ Condensation (G L) ◦ Sublimation (S G) ◦ Deposition (G S)
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We can either add or remove energy to get changes of state If we add, we call it endothermic If we remove, we call it exothermic
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Melting is the change of state from a solid to a liquid ◦ Adding energy to a solid increases its energy ◦ Particles move faster, move away from each other The melting point is the temperature at which a substance changes from a solid to a liquid ItemMelting temperature (C) State of matter at room temperature (25C) Water0 C Table salt801 C Nitrogen-210 C…-159C boiling
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Freezing is the change of state from a liquid to a solid ◦ We remove energy—molecules slow down ◦ The freezing point is the temperature at which this happens
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Evaporation is the change of a substance from a liquid to a gas ◦ We add energy—molecules speed up ◦ Does not have to have bubbles ◦ Can occur just at the surface Boiling is the change of a liquid to a gas (vapor) throughout the whole liquid
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Condensation is the change of state from a gas to a liquid ◦ We remove energy—molecules slow down ◦ Condensation point is the temperature at which a gas becomes a liquid Same as boiling point
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Sublimation is the change of state from which a solid changes directly into a gas ◦ We add a LOT of energy—molecules speed up a lot ◦ Dry ice Dry ice
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Change of temperature versus change of state ◦ When energy is added… Either the temperature changes OR the state changes Not both!
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When you add heat to a solid… ◦ …the temperature increases until the melting point You still add heat… ◦ …the temperature stays while the solid melts You now add heat to a liquid… ◦ …the temperature increases until the boiling point You still add heat… ◦ …the temperature stays while the liquid boils You now add heat to a gas… ◦ …the temperature will just keep increasing!
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Section 3: Changes of State
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State changeStarting stateEnding stateEnergy added or removed Endothermic or exothermic Melting Freezing Evaporation Condensation Sublimation Deposition
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Section Review ◦ Please answer the objectives on your objective summary sheet 1.Describe how energy is involved in changes of state 2.Identify phase changes as endothermic or exothermic 3.Describe what happens during melting and freezing 4.Compare evaporation and condensation 5.Explain what happens during sublimation and deposition 6.Identify the two changes that can happen when a substances loses or gains energy 7.Interpret a phase change(heating curve) diagram
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