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Bell Ringer What is the difference between the different states of matter? [in terms of energy or particles] based on the idea that particles are constantly moving can be applied to solid, liquid, or gas provides a model of ideal gas behavior so it is only an approximation Ideal student Real student 1. Gases consist of tiny particles that are very far apart most volume is empty spacelow density allows gases to be easily compressed 2. All collisions between particles and container walls are elastic there is no net loss of energy when particles collide total kinetic energy stays constant even though it can be transferred between particles 3. Particles are in continuous, rapid, random motion since they are moving, they have KE KE overcomes their attractive forces 4. No forces of attraction or repulsion YOU ARE ATTRACTED TO EVERYTHING! Average kinetic energy depends on temperature KE increases as temperature increases At the same T, lighter particles have higher speeds than heavier ones velocity and temperature are directly proportional ideal gas is defined by the KMT most gases behave close to the ideal when there is: HIGH temperature – so they have enough KE to overcome attractive forces Low pressure – so they are very spread out Gases with little attraction, low mass, are more ideal (monatomic gases) Create a cartoon that helps to explain the KMT to other students! Grade will be based upon: Creativity Effort Use of color Bell Ringer List the 4 parts of the KMT. P : amount of force in an area Why would shoes with smaller diameter heel not be allowed on gym floor? As surface area decreases, pressure increases Pressure exerted by a gas depends on volume temperature number of molecules STANDARD TEMPERATURE & PRESSURE STP Standard Temperature = 0°C Standard Pressure = 1 atm Pressure and Temperature STP (Standard Temperature and Pressure) standard temperature 0 oC 273 K standard pressure 1 atm 101.3 kPa 760 mm Hg Equations / Conversion Factors: K = oC + 273 oC = K – 273 1 atm = 101.3 kPa = 760 mm Hg = 760 torr Conversions Convert 25oC to Kelvin. K = oC + 273 25oC + 273 = 298 K How many kPa is 1.37 atm? X kPa = 1.37 atm 101.3 kPa = 138.8 kPa 1 atm How many mm Hg is 231.5 kPa? X mm Hg = 231.5 kPa 760 mm Hg = 1737 mm Hg 101.3 kPa Practice Conversions Is the pressure of the vapor over a liquid (and some solids) at equilibrium Must be in contact with a liquid otherwise you just have a gas! Depends on temperature only Vapor Pressure measure of the tendency for liquid particles to enter gas phase at a given temp. a measure of “stickiness” of liquid particles to each other more “sticky” less likely to vaporize In general: LOW v.p. not very “sticky” more likely to vaporize In general: HIGH v.p. NOT all liquids have same vapor pressure at same temp. Bell Ringer If the pressure inside a tire is 248 kPa, how many millilmeters of mercury is that? 1860 How Vapor Pressure is Measured Animation by Raymond Chang All rights reserved Behavior of a liquid in a closed container Boiling Point Explained 100 CHLOROFORM 80 PRESSURE 60 (kPa) 40 ETHANOL 20 WATER 0 0 20 40 60 80 100 TEMPERATURE (oC) Volatile substances evaporate easily (have high v.p.’s). BOILING when vapor pressure = confining pressure (usually from atmosphere) atmospheric pressure is 101.3 kPa b.p. = 78oC b.p. = 100oC Formation of a bubble is opposed by the pressure of the atmosphere Boiling vs. Evaporation Boiling point: atmospheric pressure = vapor pressure AIR PRESSURE 15psi VAPOR PRESSURE Revolutionary process - fast Lyophilization – freeze drying 15 psi Evaporation: molecules go from liquid to gas phase gas liquid Evolutionary process - slow Barometer measures atmospheric pressure Empty space (a vacuum) Hg Weight of the mercury in the column Weight of the atmosphere (atmospheric pressure) Practice Vapor Pressure of 4 liquids wkst 1.What is one way you can make a real gas act more ideal? 2. 92.1 kPa = _______ mmHg 3. If ethanol boils at 82°C, what is the atmospheric pressure? 4. In terms of pressure(s), when does a liquid boil? 5. Name of the two MOST ideal REAL gases? 1. Spread out, high temp or low press 2. 691mmHg 3. 110 kPa 4. When vp = atm pressure 5. H or He Bell Ringer According to Reference Table H, at what temperature will propanone boil if the atmospheric pressure is 70kPa? Evaporation H2O(g) molecules (water vapor) H2O(l) molecules Show how pressure, volume, and temperature, are related to gases. REMEMBER Hold whichever variable constant to adjust the other variable to see what would happen as a result of the desired change If the temperature remains constant and we lower the pressure, what must happen to the volume? The volume must increase! If the temperature remains constant and we lower the volume, what must happen to the pressure? The pressure must increase! Relationships between volume and pressure. Boyle’s Law: P and V as one increases, the other decreases inversely proportional pressure is caused by moving molecules hitting container walls If V is decreased and the # of molecules stays constant, there will be more molecules hitting the walls per unit of time Boyle’s Law Pressure vs. Volume for a Fixed Amount of Gas (Constant Temperature) Pressure (Kpa) 100 150 200 250 300 350 400 450 600 Volume (mL) 500 400 300 Volume (mL) 500 333 250 200 166 143 125 110 PV 50,000 49,950 50,000 50,000 49,800 50,500 50,000 49,500 200 100 0 100 200 300 Pressure (KPa) 400 500 Chucky’s Law (aka Charles Law) Relationship between volume and temperature Charles’ Law: V and T if P is constant, gases expand when heated when T increases, gas molecules move faster and collide with the walls more often and with greater force to keep the P constant, the V must increase Example: Boyle’s Law Consider a 1.53L sample of gaseous SO2 at a pressure of 5.6 x 103 Pa. If the pressure is changed to 1.5 x 104 Pa at constant temperature, what will be the new volume of the gas? P1 V1 P 2 V 2 ( 5 . 6 x10 Pa )(1 . 53 L ) (1 . 5 x10 Pa )V 2 3 4 . 57 L V 2 Practice 1. If the volume of a gas at 10.0oC is 100.0 ml, then what is the volume at -2.0oC? V1 =V2 T1 T2 T1 = 10oC 100.0 ml = V2 V1 = 100.0 mL 10.0oC -2.0oC T2 = -2.0oC 10.0 x V2 = -200 V2 = ? V2 = -20. ml We can’t have negative volumes, so we can’t use a temperature scale with negatives V1 =V2 With gas laws, ALWAYS USE KELVIN T1 T2 T1 = 10oC 283 K 100.0 ml = V2 V1 = 100.0 mL 283 K 271 K T2 = -2.0oC 271 K V2 = ? 283 x V2 = 27100 V2 = 95.7597 mL 96 mL Gas Laws pkt Vapor Pressure wkst Charles’ Law: V and T Charles’ Law: the V of fixed mass of gas at constant P varies directly with temperature. What kind of graph is V vs. T? V1 T1 V2 T2 Boyle’s Law • As the pressure on a gas increases the volume decreases 1 atm 2 atm 4 Liters 2 • Pressure and volume are inversely related Pressure-Volume Relationship 250 (P3,V3) Pressure (kPa) 200 150 (P1,V1) 100 (P2,V2) 50 P1 = 100 kPa V1 = 1.0 L P2 = 50 kPa V2 = 2.0 L P3 = 200 kPa V3 = 0.5 L P1 x V1 = P2 x V2 = P3 x V3 = 100 L x kPa 0 0.5 1.0 1.5 Volume (L) 2.0 2.5 P vs. V (Boyle’s Data) Example: Charles’ Law & Temp. A sample of gas at 15.0°C and 1.00 atm has a volume of 2.58 L. What volume will this gas occupy at 38.0°C and 1.00 atm? P1 = 1.00 atm T1 = 15.0oC = 288K V1 = 2.58 L V1 =V2 T1 T2 2.58 L 288K V2 x 288K V2 = V2 311K = 802L*K = 2.79L P2 = 1.00 atm T2 = 38.0oC = 311K V2 = ? Bell Ringer If the pressure on a gas is decreased by ½, how much larger will the volume become? 2. Which gases makes the most ideal gases real gases? 1. Cooling Curve Review Gas Laws Lab Bell Ringer Four identical balloons contain equal volumes of gas at STP. A. B. Balloon #1 contains H2 gas Balloon #2 contains He gas Balloon #3 contains O2 gas Balloon #4 contains N2 gas Which balloon would weigh the most? Explain According to the KMT, why would the balloons expand upon heating? Bell Ringer If you have a basketball that has a volume of 2.2L at a pressure of 3.00atm. What would it’s volume be at Standard Pressure? 1. As the temperature of a liquid increases, its vapor pressure A. Increases B. Decreases C. Remains the same 2. According to Reference Table H, what is the vapor pressure of propanone at 45ºC? 70.0 kPa 3. What is the name of the of the phase change that turns a solid directly into a gas? Sublimation 4. Which liquid on Table H has the strongest Ethanoic Acid intermolecular forces of attraction? Amadeo Avogadro created two important ideas used in science 1. Hypothesis If we have two gases with the same temperature and pressure at the same volume, they will have the same number of molecules. Gases are made of mostly empty space, so the size of the individual molecules does not matter Example - A sample of H2(g) contains 1 x 1023 molecules at a particular volume at STP. How many molecules of CO2(g) takes up the same volume at STP? Same T, same P and same V 1x = same # of molecules 23 10 2. Molar volume of a gas In chemistry, we use very large numbers of atoms. So Avagadro created a large unit called Mole = 602,000,000,000,000,000,000,000 objects Pair = 2 Dozen = 12 Mole = 6.02 x 1023 If we have one mole of ANY gas at standard temperature and pressure, it will take up of space Examples 1. How much room does 6.02 x 1023 molecules of N2(g) occupy at STP? One mole = 22.4 L 2. How much volume does 0.5 moles of CO2(g) occupy at STP? 11.2L 3. If we have 3.01 x 1023 molecules of CO2(g) at STP, what is the volume? 0.5 moles 11.2 L 4. How many molecules are in 44.8 L of H2S(g) at STP? 2 moles 2 x 6.02 x 1023 1.204 x 1024 5. If we have 9.03 x 1023 molecules of a gas at STP, what is the volume? 1.5 moles 33.6 L Dalton’s Law of Partial Pressure Dalton’s Law of Partial Pressure the total P of a mixture of gases is equal to the sum of partial P of component gases, no matter how many different gases PT = P1 + P2 + P3 + … Partial Pressure- P of each gas in mixture Why? the particles of each gas in a mixture have an equal chance to hit the walls so each gas exerts P independent of that exerted by other gases total P is result of the total # of collisions per unit of wall area Table H worksheet Bell Ringer According to Reference Table H, which liquid will evaporate more rapidly? At what temperature does ethanol have the same vapor pressure as propanone at 68.5˚C? Bell Ringer A gas sample has a volume of 25.0 ml at a pressure of 1.0 atm. If the new volume increases to 50.0 ml and the temperature remains constant, the new pressure will be? a gas often changes in T, P, and V all at once the other gas laws can be combined into one law Combined Gas Law- relationship between P, V, and T of a fixed amount of gas Example - A gas is collected at 273 K and 2.00 atm to a volume of 50.0 ml. What is the new pressure of a gas if the temperature drops to 200.0 K and the volume increases to 75.0 ml? P2 = ? P1 = 2.00 atm V1 = 50 mL V2 = 75.0 ml T1 = 273 K T2 = 200.0 K 2.00 x 50 ml = P2 x 75.0 ml 273 K 200.0 K 20,475 x P2 = 20,000 P2 = 0.97680 atm 0.977 atm A Helium-filled balloon has volume of 50.0 L at 25°C and 1.08 atm. What volume will it have at 0.855 atm and 10.°C? P1 = 1.08 atm P2 = 0.855 atm V1 = 50.0 L V2 = ? T2 = 10.°C = 283 K T1 = 25°C = 298 K (1.08 atm)(50.0 L) (0.855 atm)(V2) = 298 K 283 K 254.79 x V2 = 15282 V2 = 59.9788 L 60. L Bell Ringer Which 5.0 ml sample of NH3 will take the shape of and completely fill a closed 100.0 ml container? A. NH3(s) C. NH3(g) B. NH3(l) D. NH3(aq) Sub Gas Laws and Boyles Problems Bell Ringer Which sample at STP has the same number of molecules as 5 liters of NO2(g) at STP? A.5 grams of H2(g) B. 5 liters of CH4(g) C. 5 moles of O2(g) D.5 x 1023 molecules of CO2(g) A Helium-filled balloon has volume of 50.0 L at 25°C and 1.08 atm. What volume will it have at 0.855 atm and 10.°C? P1 = 1.08 atm P2 = 0.855 atm V1 = 50.0 L V2 = ? T2 = 10.°C = 283 K T1 = 25°C = 298 K (1.08 atm)(50.0 L) (0.855 atm)(V2) = 298 K 283 K 254.79 x V2 = 15282 V2 = 59.9788 L 60. L Bell Ringer A 1.00-mole sample of a neon gas occupies a volume of 22.4 liters @ 298K and 101.3 kPa. Calculate the density of this sample. 0.827 g/L Bell Ringer Using Table H, how would you have to adjust your cooking time of pasta high in the mountains? Water rapidly boiling on a stove Water rapidly boiling on a stove Pressure Cooker Copyright © 2006 Pearson Benjamin Cummings. All rights reserved. 120oC Pressure Cooker Copyright © 2006 Pearson Benjamin Cummings. All rights reserved. 120oC Bell Ringer A gas occupies a volume of 560.ml at a temperature of 100.°C. To what temperature must the gas be changed if it is to occupy 400.ml, with the pressure remaining unchanged? Heating / Cooling Curve of Water 140 steam Temperature (oC) 120 water and steam 100 liquid water 80 60 40 ice and water 20 0 ice -20 Heat added at a constant rate