2Pretest on prior knowledge CW creditNot for a grade, just to see what you already know Good Luck!
3States of Matter ESSENTIAL QUESTIONS OBJECTIVES Compared to solids and liquids, what is unique about gases?How do substances change from one state to another?Recall properties on states of matterExplain why gases are easier to compress than solids or liquidsAnalyze and interpret a phase diagram
4Chemcatalyst: __.__ Name some properties of solids: Can you give some examples of solids?
5Solids Particles have fixed locations Packed tightly together in an orderly arrangementVibrate in place
6Properties of solids Not easily compressible Do not FLOW because they are packed tightlyNo effect with an increase of pressure
7Think back…Which type of compounds are only solids at room temperature??IONIC COMPOUNDS
8Crystal Structure Orderly arranged particles in a pattern Also, known as a latticeA unit cell is the smallest part of a crystal that retains its shape
9Allotrope A substance that exist in more than one form Carbon has 3 allotropesGraphite (in pencils)Diamonds (thanks Mr. Herman)Buckministerfullerene (C60)
10Phosphorus Red or white Other AllotropesOxygen O2 or O3Phosphorus Red or white
11Amorphous solidsA solid that lacks order within its internal structureThese solids are randomly arrangedExample: Glass, plastic, synthetic fibers, rubber
14Chemcatalyst :__.__Why do you add salt to a pot of water?
15Liquids Particles are spaced out more than solids Particles feel attraction between each other which keeps them closeLess dense than solids
16Properties of Liquids Take the shape of the container Definite volume Ability to flow (fluid)No effect with an increase of pressure
17What’s a fluid?A continuous substance whose molecules move freely past one another and that has the tendency to assume the shape of its container
18Boiling PointA liquid is heated to a temperature where the particles have enough kinetic energy to vaporizeThe liquid begins to bubble because the vapor is rising and escaping the container
19Boiling Point (BP)At a particular temperature the vapor pressure is equal to the external pressureDuring the boiling process the temperature is constantSince, its based on pressure, not all liquids will boil at the same temperature
20BP & Pressure Altitude will affect boiling points As you go up to higher altitudes, the pressure is lower; which in turn would lower the boiling point.
21Think about this…Would the temperature at which water boils be higher or lower than 100oC?Denver is 1600 m above sea levelWater actuallyboils at 95oC!!!
22Kinetic energy and states of matter If Kinetic energy increases all particles begin to move faster and in turn change phaseKinetic energy is directly proportional to temperature
23Did you know?!At higher altitudes, a pressure cooker is used so the vapor cannot escape and the food will cook more quickly!Due to the higher pressure, the more heat needed to have the water boil
24Why do you add salt to a pot of water? By adding salt to your pot, it raises the BP to 102oC, but salt water has a lower heat capacity than typical water.Needs less energy to heat the waterWhat would be a more effective way to boil water, than salt?Think about pressure
25Small scale LabThe behavior of liquids and solids
26Chemcatalyst __. __Explain the differences between a NaCl crystal compared to a piece of glass.What happens to kinetic energy when temperature decreases?If the pressure is lower, does boiling point change?
27Gases Small, hard particles Empty space in between Particles are far apart
28Gases Insignificant volume and no shape No attractive or repulsive forces between particlesMove in straight lines until a collisionElastic collisionsFlows like a fluid
30Is a gas a fluid?Gases have the ability to flow because they can move past one anotherWhat happens over time as Bromine gas is left in the beaker?
31Is there a difference between a gas and a vapor? At room temperature, a gas is a gasExample: Chlorine gas (Cl2), oxygen gas (O2)At room temperature, a vapor is in some other formExample: Water Vapor (H2O)
32Gas Pressure Results from the force exerted by the gas on an object What is causing this force?The particles colliding with themselves and the objectThe force applied is very small for one, but imagine millions!!
33Gas Pressure & a VacuumA vacuum is where there are no particles, thus no pressureSpace is a vacuum!
34Think about this… Why can no one hear you scream in space? It’s a vacuum and sound needs a medium to travel
35Measuring Pressure Barometer Used to measure atmospheric pressure Air pressure decreases as altitude increases
37Chemcatalyst __.__ Solid Liquid Gas Match the Property with the correct state of matter:SolidLiquidGasBACA or BAbility to flow and has a definite volumeAn ordered pattern with particles in fixed positionsParticles have elastic collisionsParticles feel attraction between each otherParticles vibrate in placeMove in straight lines, until a collision
38Changes of StateA physical change occurs as a substance undergoes a change from solidliquidgasEnergy is needed to complete this change
39Solid LiquidMeltingParticles within a solid gain enough energy to move into the liquid phaseThe organization of the particles break downMelting point (MP) the temperature at which it goes from solid liquid
40Liquid Solid Freezing Lowers the energy or temperature where particles become more rigid in its shapeFreezing Point (FP)- the temperature where a liquid begins to freeze
41Did you know?!The melting point and the freezing point is the same EXACT temperature!!!Meaning solid and liquid are at equilibrium, until it shifts towards either one
42Think back… Which one has a higher melting point? Salt or Sugar? (NaCl or C12H22O11 )Salt is an ionic compound, while sugar has weaker covalent bonds
43Liquid Gas Evaporation Also, known as vaporization When liquid particles gain enough energy to leave the liquid phase and escape as a gasSince, the most energetic particles are leaving the leftover temperature decreases
44Did you know?! Evaporation is a cooling process By sweating, your sweat is evaporated and in turn cooling down your body
45Gas Liquid Condensation A loss of energy returns the gas to the liquid phase
46Solid Gas Sublimation A solid skips the liquid phase and becomes a gasOccurs when the solid has a vapor pressure that is greater than atmospheric pressure at or near room temperature.
47But doesn’t sub mean below? Sublimation is from the Latin word sublimare, which means to raise or elevate!!
48Gas SolidDepositionGas/vapor becomes a solid and skips the liquid phaseUsed for making computer chips and purifying mixtures!
49Let’s make this concept map SolidSublimationDepositionMeltingFreezingCondensationEvaporationGasLiquid
50Answer the following in complete sentences: Is a phase change a chemical or physical change and explain why.
51Chemcatalyst: __.__Which change of state occurs when liquid becomes solid?Is there an increase or decrease of temperature/kinetic energy for this change?What happens to the particles during this change?
52Phase DiagramA phase diagram shows the relationship between the 3 statesShows conditions (temperature & pressure) at which phases are at equilibrium
53Phase diagramLet’s shade the 3 phases of our diagram
54Phase Diagram Triple Point- where all 3 states exist at once Critical Point- no phase boundaries exist
55Phase DiagramEach line represents an equilibrium between changes of states
56Phase DiagramNormal means at standard pressureOr MP
57Phase diagram Practice What temperature and pressure is the triple point?What temperature and pressure is the critical point?What temperature and pressure of the normal MP and BP?
58Phase diagram Practice A. PressureB. TemperatureC. Triple pointD. solidE. LiquidF. Gas/VaporG. Critical PointH. Normal FP/MPI. Normal BP
59Chemcatalyst __.__Describe what’s happening:A B G H F C
60Label and answer the following: What state of matter would be at 75.0 Kpa and -120oC?2. What is the normal boiling point for Xe?