Properties of Solids, Liquids and Gases Property Solid Liquid GasPositionExpansionShapeVolumeCmprsbltyDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansionShapeVolumeCmprsbltyDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShapeVolumeCmprsbltyDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShape Definite None NoneVolumeCmprsbltyDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShape Definite None NoneVolume Maintains Maintains AnyCmprsbltyDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShape Definite None NoneVolume Maintains Maintains AnyCmprsblty In-compress Slightly VeryDensityMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShape Definite None NoneVolume Maintains Maintains AnyCmprsblty In-compress Slightly VeryDensity High High LowMixing
Properties of Solids, Liquids and Gases Property Solid Liquid GasPosition Fixed Limited RandomExpansion V. limited V. limited infiniteShape Definite None NoneVolume Maintains Maintains AnyCmprsblty In-compress Slightly VeryDensity High High LowMixing Xtrmly slow Slow Fast
What are some phase changes Solid Liquid melting Liquid Solid freezing Liquid Gas vaporization Gas Liquid condensation Solid Gas sublimation Gas Solid deposition
Endothermic / Exothermic Processes that give off energy are called exothermic. Processes that absorb energy are called endothermic
Endothermic or Exothermic ???Solid Liquid melting Endothermic ???Liquid Solid freezing ??? Exothermic Liquid Gas vaporization Endothermic ??? Gas Liquid condensation Exothermic ??? Solid Gas sublimation Endothermic ??? Gas Solid deposition Exothermic ???
Relate this to weather …Condensation of water vapor to rain drops gives off heat – exothermic.Evaporation of water to form water vapor absorbs heat, and cools the surroundings – endothermic.The formation of snow from water vapor gives off heat – exothermic.
Phase changes and the … transfer of energySuppose you put a few drops ofalcohol on the back of your hand? Why does it feel cold? Evaporation is an endothermicprocess and absorbs heat from the surroundings, your hand.
Vapor Pressure 1. Consider a sealed container with water. 1 2 32. Some of the water 3. Some of the waterevaporates to make vapor condenses towater vapor make liquid water
Water / water-vapor equilibrium A dynamic equilibrium is established when the vapor rate at which liquid water evaporates into water vapor equals the rate at which water water vapor condenses into liquid water.
The pressure of the water vapor varies with thePressure gauge temperature. vapor Temp. Digital Thermometer Pressure 23 C water
What’s theconnection betweenvapor pressure and boiling?
Boiling occurs at thetemperature where the vapor pressure of the liquid equals the ambient pressure.
What is the boiling point of water here?Look at a Water boils at sea level atvapor pressure 100 C where the ambienttable. pressure is 760 mm Hg. The ambient Therefore, water pressure here is must boil between usually less than 95 C and 100 C, 700 mm Hg. usually around 97.5
Temperature Corresponding vapor pressure in mm Hg (or Torr) At 100 C the vapor pressure is 760 mm Hg
Therefore waterboils at 100 Cwhen the vaporpressure of waterequals theambient pressureof 760 mm Hg
Water boils atthe temperaturewhere the vaporpressure equalsthe ambientpressure.
When theambientpressure is 690,water will boilat thetemperaturewhere the vaporpressure is 690
Heat of FusionFuse means “to melt”The heat of fusion is the heat needed to melt one gram of a substance at the melting point.The heat of fusion of ice can be found experimentally.
Latent heatSometimes the heat of fusion or heat of vaporization is called the latent heat, or the latent heat of fusion or vaporization.Latent heats can use the following symbols: Lf or Hf Lv or Hv
Suppose you had a hot cup of coffee …… and you wanted to cool it. You could …1. Blow on it.2. Stick it in the refrigerator3. Add ice to it.
By adding ice …… you cool the coffee because the ice melts at 0.0 C,extracting heat from the coffee, and cooling the coffee. The amount of cooling can be calculated using the heat of fusion of ice.
Measuring the heat of fusion of ice Add iceAdd ice to calorimeter Ti of hot Temp. water probe Tf of all Time water All ice melts Calorimeter Temperature with hot water
The calculations are basedon conservation of energy. The heat lost by the hotwater is equal to the heatgained by the melting iceand the water that comes from the ice.
Q lost = Q gained m hw c∆Thw = m i H fus + m i c∆Tiw Heat gained Heat gained byHeat lost by hot by ice as it “ice water” aswater as it cools melts to make it warms from water at 0.0 C 0.0 to Tf Hfus = heat of fusion hw = “hot water” i = “ice” iw = “ice water” c = 4.18J/gC Solve the equation for Hf
Solve for Qf the heat of fusion Q lost = Q gainedm hw c∆Thw = m i H f + m i c∆Tiw m hw c∆Thw - m i c∆Tiw Hf = mi
Heat of fusion data1. Mass of calorimeter cup2. Mass of cal cup and hot water3. Mass of hot water4. Initial temperature of hot water5. Final temperature of all water6. Mass of cal cup and all water7. Mass of ice added
Procedure1. Heat up water on hot plate2. Set up computer, load calibration file3. Set up “Graph in real time” parameters4. Mass calorimeter cup5. Add hot water and mass cup6. Get baseline temp. of hot water (~ 45 s)7. Add ice – monitor temp – get Ti and Tf from “Plot graph” and “examine data”8. Mass calorimeter cup and all water
Initial ObservationsA clear, colorless liquid has a strong, alcohol-like odor. When placed on a watch glass and ignited, it burns, but not completely. Some nonflammable liquid remains. Is the liquid a pure substance? Is the liquid a mixture? Heterogeneous or homogeneous?
How could you separate a mixture of two clear, colorless liquids? What if the liquids have different boiling points?
What does a“temperature vs time” graph look like for a single liquid?
Heating curve for a liquid Temperature hits a plateau as liquidtemperature boils Boiling point of liquid time
Heating curve for a liquid Temperature rises when all liquid istemperature vaporized Boiling point of liquid time
Heating curve for two liquids, A and B Boiling point time of liquid B Boiling point of liquid A
Fractional distillation can be used to separate the mixture into its various “factions”. Isolate each fraction at each of the different boiling points.
Collecting the first fraction B 3 A Collect in the time 2 first test tube 1 what comes off in region 1.
Collecting the second fraction B 3 A Collect in the time 2 second test tube 1 what comes off in region 2.
Collecting the third fraction B 3 A Collect in the time 2 1 third test tube what comes off in region 3.
Predict what is in each tube Test tube 1 May contain only A B Test tube 2 A May contain both time 3 A and B 2 1 Test tube 3 temperature May contain only B
Equipment setup for doingRing stand fractional distillation.and fingerclamp thermometer or temperature probe sidearm boiling Jones condenser flask beaker or hot plate test tube
Change the test tube in the beaker toRing stand collect each fractionand fingerclamp thermometer or temperature probe sidearm boiling Jones condenser flask beaker or hot plate test tube
Test the contents of each test tube for …1. Odor – does it have an odor? Is it strong or weak?2. Flammability – does it burn? A lot or a little?Test by place a small amount on a watch glass and igniting it with a match.
Record your observations Start End Flam-TT# Temp Temp Odor mability 1 2 3
Do the lab and report yourfindings to the class.