Gas Laws. What will students know and be able to do by the end of this unit?

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2 Gas Laws What will students know and be able to do by the end of this unit? o Define the 5 key points of the Kinetic Molecular Theory o Compare real gases to ideal gases o Solve problems using the Gas Laws Key Subject Competencies o Describe the difference between Real and Ideal gases according to the Kinetic- Molecular theory of gases, o Understand and use Boyle's Law. o Understand and use Charles' Law. o Understand and use the Combined Gas Law. o Understand Avogadro's Hypothesis o Use the above laws to solve problems. Vocabulary o Boyle's Law o Charles' Law o Combined Gas Laws o Ideal Gas Law o Real Gasses o Kinetic Molecular Theory o Avogadro's Hypothesis

3 The Kinetic Molecular Theory 2.). 3.). 4.). Deviations to Rule: 1.) 2.) Conclusion:

4 Name Ms. Tintella 1, A sample of a gas is contained in a closed rigid cylinder. According to kinetic molecular theory, what occurs when the gas inside the cylinder is heated? 1) The number of gas molecules increases. 2) The number of collisions between gas molecules per unit time decreases. 3) The average velocity of the gas molecules increases. 4) The volume of the gas decreases. 2. Which diagram best represents a gas in a closed container? i) 3) O A KMT Date Regents Chemistry Under which conditions of temperature and pressure would helium behave most like an ideal gas? 1) 50 K and 20 kpa 3) 750 K and 20 kpa 2) 50 K and 600 kpa 4) 750 K and 600 kpa The kinetic molecular theory assumes that the particles of an ideal gas 1) are in random, constant, straight-line motion 2) are arranged in a regular geometric pattern 3) have strong attractive forces between them 4) have collisions that result in the system losing energy The concept of an ideal gas is used to explain 1) the mass of a gas sample 2) the behavior of a gas sample 3) why some gases are monatomic 4) why some gases are diatomic 2) A

5 The Gas Laws Boyle's Law Charles's Law Draw Graph Relationship Formula

6 The Gas Laws Gay Lussac's Combined Gas Law Draw Graph N/A Relationship N/A Formula Constants N/A

7 Avagadro's Hypothesis

8 Ms. Tintella 1. The data table below gives the temperature and pressure of four different gas samples, each in a 2-liter container. Temperature and Pressure of Gas Samples Gas Sample He Ne C02 CH4 Temperature (K) Pressure (atm) Which two gas samples contain the same total number of particles? 1) CH4andCO2 3) HeandC02 ' 2) CH4andNe 4) HeandNe Do Now Date Regent Chemisrty 3. At the same temperature and pressure, 1.0 liter of C0(g) and 1,0 liter of C02(g) have 1) equal masses and the same number of molecules 2) different masses and a different number of molecules 3) equal volumes and the same number of molecules 4) different volumes and a different number of molecules 4. A sample of H2(g) and a sample of N2(g) at STP contain the same number of molecules. Each sample must have 1) the same volume, but a different mass 2) the same mass, but a different volume 3) both the same volume and the same mass 4) neither the same volume nor the same mass A sample of oxygen gas is sealed in container X. A sample of hydrogen gas is sealed in container Z. Both samples have the same volume, temperature, and pressure. Which statement is true? 1) Container X contains more gas molecules than container Z. 2) Container X contains fewer gas molecules than container Z. 3) Containers X and Z both contain the same number of gas molecules. 4) Containers X and Z both contain the same mass of eas. 5. At STP, 1 liter of O2 would have the same number of molecules as 1) 1 liter of H2 3) 3 liters of C02 2) 2 liters of CO 4) 0.5 liter of Ne

9 : Form WS 6.5.1A PHASES OF MATTER Name Date Period How do gases behave? In order to study gases, chemists have devised a model. The model is called an ideal gas (a gas which explains the behavior of all gases). This Ideal Gas model is based on the following assumptions, and can be applied only under conditions of LOW PRESSURE AND HIGH TEMPERATURE. MOTION - gas molecules are continuously moving in a random, straight line motion. *JA COLLISION- when gas molecules collide with each other or with the walls of the container there is no energy lost. Therefore, the total energy of the system never A changes. '/. VOLUME - the actual volume of the molecules is insignificant when compared to the volume of the contained area (the container). ATTRACTION - no attraction exists between molecules. Gases deviate from the ideal conditions when conditions of HIGH PRESSURE AND LOW TEMPERATURE exist These conditions lead to confinement and intermolecular attractions begin to act. VOLUME gas molecules do have a volume of their own. ATTRACTION- there does exist a force of attraction between gas molecules. The above factors (deviations) allow for the existence of gases as either solids or liquids under certain conditions, Answer the questions below based on your reading above and on your knowledge of chemistry. 1. Of the following: H2Cg); He(g); CO2(#); which would behave least like an ideal gas? Why? _ 2, Compared to other gases, why doesn't water vapor behave like an ideal gas? 3. Why do gases behave least like ideal gases at low temperature and high pressure? 4. The relationship between the Kelvin temperature and volume of a gas is linear until the temperature begins to approach 0 K. Why? Evan P. Silberstein, 2003

10 : Form N6.57V PHASES OF MATTER Name Date Period f to describe ideal gases Kinetic theory of gases (under ideal circumstances) if Gas are composed of particles that are in constant, rapid, random, linear motion. if Collisions between gas particles are elastic so no energy is lost As a result, the pressure of a gas at a constant temperature and volume remains constant it The volume of the particles of a gas is so small compared to the distance between them, it is considered zero. The gas is mostly space. if There is no attraction or repulsion between gas molecules if The average kinetic energy of the molecules of a gas is directly proportional to the Kelvin temperature of the gas Deviations from ideal gases if Particles of gas do have volume if Gas particles do exert forces on each other Optimum conditions if High temperature if Low pressure if Low molecular mass Answer the questions below by circling the number of the correct response 1. Which gas will most closely resemble an ideal gas at STP? 1)S02. 3)CI2 2} NH3 4} H2 2. At STP, which gas would most likely behave as an ideal gas? (1)H2 (3)CI2 (2) C02 (4) S02 3. Which gas has properties that are most similar to those of an idea! gas? (1)02 (3)NHa (2)H2 (4)HCI 4. Under which conditions does a real gas behave most like an Ideal gas? 1 at high temperatures and low pressures 2 at high temperatures and high pressures 3 at low temperatures and low pressures 4 at low temperatures and high pressures 5. Under the same conditions of temperature and pressure, which of the following gases would behave most like an ideal gas? (1)He(g) (3)CI2(g) (2)NH,(g) (4)C02(g) 6. Which gas has properties that are most similar to those of an ideal gas? d)na (3) He (2}02 (4)Xe 7. One reason that a real gas deviates from an ideal gas is that the molecules of the real gas have 1 a straight-line motion 2 no net loss of energy on collision 3 a negligible volume 4 forces of attraction for each other Evan P. Silberstein,

11 : Form WS A PHASES OF MATTER Name Date Period If a balloon is pulled over the neck of a flask, and the setup is placed on a hot plate, the balloon blows up as it heats up. This happens even though no additional air can get into the balloon. As the air heats up, it expands. The air can be squeezed back into a smaller space by', increasing the pressure on it. This is what causes the diver in a Cartesian diver to sink when pressure is put on its container. The relationship between the temperature, pressure, and volume of a gas is known as the combined gas law. THE LAW ^-^- = P X V Where: P, - initial pressure V] = initial volume T; - initial temperature (K) P2 = final pressure V2 = final volume T2 = final temperature (K) The equation has six variables. Generally, five variables must be provided in order to solve for the sixth. If either temperature, pressure, or volume is constant, they cancel out, making an equation of four variables. Sample Problem A gas with a volume of 250. ml at35 C and kpa is heated to 57 C and the pressure is increased to kpa. What is its new volume? T} = = 308 ; T2 = A: r\i PV _ riyi PV T 179mL (Continue

12 : Form N6.4.1A PHASES OF MATTER Using the Combined Gas Law Page 2 Fill in the blanks in the table below by using the combined gas law to find the unknown variable in each row. Initial Final volume pressure temperature volume pressure temperature ml 96kPa 27 C 99.0 kpa o.o c ml SP* ST* 96.6 kpa 35.0 C L 95.3 kpa -45 C SP" ST* L atm 375 K atm 350. K atm 30.0 C 185mL atm 28.0 C 6.!6.5mL 107.3kPa 26,5 C 18.0 ml 104.4kPa ml atm ' 75.5 C 16.5mL 70.2 C L C L 104.2kPa 98.5 C OL SP ST SP 27.3 K L SP ST 111.4kPa 87 C *SP = Standard Pressure (101.3 kpa or 1.0 atm) ST= Standard Temperature (0 C or 273 K) Evan P. Silberstein,

13 : Form N6.4A PHASES OF MATTER Gas Laws Page 2 Number of particles * Equal volumes of different gases at the same temperature and pressure contain an equal number of particles. Standard temperature and pressure (STP)- agreed upon value of temperature and pressure for the sake of comparing gases * Temperature: 0 C or 273 K ir Pressure: kpa or 1 atmosphere Answer the questions below by circling the number of the correct response 1. A sample of a gas is at STP. As the pressure decreases and the temperature increases, the volume of the gas (1) decreases (2) increases (3) remains the same Base your answers to questions 2 and 3 on the graphs shown below. (1) (2P Note that questions 2 and 3 have only three choices. 2. Which graph best represents how the volume of a given mass of a gas varies with the Kelvin temperature at constant pressure? 3. Which graph best represents how the volume of a given mass of a gas varies with the pressure on it at constant temperature, 4. A100. milliliter sampie of a gas at a pressure of 50.8 kpa is reduced to 25.4 kpa at constant temperature. What is the new volume of the gas? (1) 50.0 ml (2) 90.0 ml (3) 200. ml (4) 290. ml 7. As the temperature of a sample of gas decreases constant pressure, the volume of the gas (l)decreases (2) increases (3}remainsthe same 8. A 100 milliliter sample of a gas is enclosed in cylinder under a pressure of kpa. What volume would the gas sample occupy at a pressure of kpa, temperature remaining constant? (1)50 ml (2) 100 ml (3) 200 ml (4) 380 ml 9. The volume of a sample of hydrogen gas at STP is 1.00 liter. As the temperature decreases, pressure remaining constant, the volume of the sample (1) decreases (2) increases (3) remains the same 10. The pressure on 200. milliliters of a gas at constant temperature is changed from 0,500 atm to 1.00 atm. The new volume of the gas is (1) 100. ml (2) 200. ml (3) 400. ml (4) 600. ml 11. As the pressure on a given sample of a gas increases at constant temperature, the mass of the sample (1) decreases (2) increases (3) remains the same 12. A gas sample is at 10.0 C. If pressure remains constant, the volume will increase when the temperature is changed to (1) 263 K (2) 283 K (3) 273 K (4) 293 K 5. At STP, which gas would most likely behave as an ideal gas? (1)H2 (2) C03 (3) Cc (4) S02 6. At constant temperature the pressure on 8,0 liters of a gas is increased from 1 atmosphere to 4 atmospheres. What will be the new volume of the gas? (1)1.00 (2)2.00 (3)32e (4)4.00 Evan P. Silberstein,

14 : Form WS6.4.2A Name PHASES OF MATTER Date Period Calculate the answers to the problems below using the gas laws. 1. What is the new volume of a gas if 50 ml at 81.0 kpa has its pressure increased to kpa? (Temperature is constant.) ml of H2 gas at 0 C and kpa is changed to S.T.P. What will be its new volume? ml of N2 gas at 127 C is cooled to 27 C, while its pressure is kept constant..what is the new volume? 4. One thousand four hundred liters of N2 gas at a pressure of 1.25 atmospheres has its pressure changed to 17.5 atmospheres. What will be its new volume at the new pressure? (Temperature is constant.) 5. Hydrogen gas occupies a volume of 400 ml at 27 C. Find the volume it will occupy if the temperature is increased to 57 C? (Pressure is kept constant.) 6. What is the pressure that must be exerted on 300 ml of a gas which has been collected at STP So that it may be confined to a volume of 190 ml? (Temperature is kept constant.) 7. If 260 ml of 02 gas is collected at 21 C and kpa, what volume would this gas occupy at STP? liters or a gas at 52 C is to be expanded to 72 liters. To what temperature must this gas be changed? (in degrees Celsius) 9. A student collected 20 ml of a gas at 96 kpa. If the temperature remains constant, what volume will the gas occupy when the pressure is changed to 112 kpa? 10. What is the volume do 482 liters of gas occupy if the temperature of the gas is changed from standard temperature to 27 C while the pressure is held at standard pressure? 11. A gas that was collected at 27 C and 52.0 kpa occupied 200 ml. What will its new volume be if its temperature is changed to 50 C and its pressure to 40.0 kpa? (Note: notice the changes that are taking place in this problem.) Evan P. Silberstein,

15 Mr. Mignella Name Chemistry. date section I. Pressure-temperature gas law problems 1. A sample of gas has a pressure of 725 torr at 18 C. What is the new temperature if the pressure is increased to 800 torr? Assume that volume is held constant. 2. A tank of gas has a pressure of 2.75 atm at 20 C. What will be the new pressure if its temperature is increased to 100 C if the volume is held constant? 3. A flask of gas is sealed at STP. What will be the pressure of the confined gas if the gas is cooled to -25 C? Assume that volume is held constant. 4. A tank of gas is filled to a pressure of 5 atm at 75 C. At what temperature will its pressure become 3.5 atm? Assume that the volume is held constant. H. All gas laws mixed 5. A 10 ml sample of gas at 300 C is to be cooled at constant pressure until it reaches half of its original volume. At what temperature will this sample reach half of its original volume? 6. A 5 0 gram sample of a gas is at STP and occupies a volume of 1.75 L. If the pressure is held constant, what will the new temperature be if the volume is increased to A sample of gas occupies 125 ml at STP. If the temperature is held constant, what will the new volume be when the temperature is increased to 1000 terr? 8. The temperature of a tank of gas whose pressure is 650 torr is changed from 27 C to 127 C. What will the new pressure be if the volume is held constant? j' 9. A sample of gas occupies 2.50 L at 1.15 atm of pressure. What is its new volume at STP? Assume that temperature remains constant. 10. The volume of a sample of gas at STP is 2.50 L. What is the new volume if the gas is warmed to 50 C at constant pressure? 11. If a gas is held at a constant volume and has a pressure of 700 torr at 10 C, what will be its new temperature when the pressure is increased to 740 torr? HI. Using the Combined Gas Law 15

16 12. A helium balloon with a volume of 410. Mi is cooled from 27 C to -27 C. The pressure on the gas is reduced from 110. KPa to 25.0 KPa. What is the new volume of the gas? 13. A gi-s" occupies 2.0 ml at 100. K, exerting a pressure of 100. Kpa. What volume would the gas occupy at 400. K if the pressure is increased to 200. Kpa? 14. A sample of methane that initially occupies 850. ml at 500. KPa and 227 C is compressed to a volume of 700 ml. To what temperature will the gas need to be cooled to lower the pressure of the gas to 200 KPa? 15. A sample of C02 gas occupies 45 ml at 750 K and 500 KPa. What is the volume of this gas at STP? ' ', : ' 16. An 8.00 L sample of neon gas at 25 oc exerts a pressure of 900 KPa. If the gas is. compressed to 2.00 L and the temperature is raised to 225- oc, what will the new.-,, pressure be?. '. ;,,. 16

17 Name Ms. Tintella 1. A sample of helium gas has a volume of 900. milliliters and a pressure of 2,50 atm at 298 K. What is the new pressure when the temperature is changed to 336 K and the volume is decreased to 450. milliliters? 1) atm 3) 5.64 atm 2) 4.43 atm 4) 14.1 atm 2. A gas occupies a volume of 444 ml at 273 K and 79.0 kpa. What is the final kelvin temperature when the volume of the gas is changed to 1880 ml and the pressure is changed to38.7kpa? 1) 31.5K 3) 566 K 2) 292 K 4) 2360 K 3. A 3.00-liter sample of gas is at 288 K and 1.00 atm. If the pressure of the gas-is increased to 2.00 atm and its volume is decreased to 1.50 liters, the Kelvin temperature of the sample will be 1) 144 K 3) 432 K 2) 288 K 4) 576 K 4. As the temperature of a gas increases at constant pressure, the volume of the gas 1) decreases 3) remains the same 2) increases 5. The temperature of a 2.0-liter sample of helium gas at STP is increased to 27 C and the pressure is decreased to 80. kpa What is the new volume of the helium sample? 1) 1,4 L 3) 2.8 L 2) 2.0 L 4) 4.0 L 6. The pressure on a 200-milliliter sample of CO2 (g) at constant temperature is increased from 60 kpa to 120 kpa. What is the new volume of the gas? 1) looml 3) 400 ml 2) 300 ml 4) 600 ml 7. Standard temperature and pressure are 1) 0 Cand l.ookpa 2) 0 Cand kpa 3) 273 Candl.OOkPa 4) 273 Cand kpa 8. Standard temperature and a pressure of 0.5 atmosphere are equal to 1) 0 C and 51.6 kpa 3) 0 C and kpa 2) 32 Cand51.6kPa 4) 32 C and kpa Gas Law Practice Date Regents Chemistry 9. Which graph best shows the relationship between the pressure of a gas and its average kinetic energy at constant volume? 10. 2) 3) 4) a. Average K.E. Average K.E. Average K.E. Average K.E. A gas has a volume of 1,400 milliliters at a temperature of 20. K and a pressure of 1.0 atm. What will be the new volume when the temperature Is changed to 40. K and the pressure is changed to 0.50 atm? 1) 350 ml 3) 1,400 ml 2) 750 ml 4) 5,600 ml 17

18 11. A cylinder with a tightly fitted piston is shown in the diagram below. Air at constant temperature As the piston moves downward, the number of molecules of air in the cylinder : 1) decreases 3) remains the same 2) increases 12. If 60. liters of hydrogen gas at 546 K is cooled to 273 K at constant pressure, the new volume of the gas will be 1) 120 L 3) 30. L 2) 20. L 4) 40. L 13. A gas occupies a volume of 500. milliliters at a pressure of 38.0 kpa and'a temperature of 298 K. At what temperature will the gas occupy a volume of 250. milliliters and have a pressure of 76.0 kpa? 1) 149K 3) 447K 2) 298 K 4) 596 K 14. A 2.5 liter sample of gas is at STP. When the temperature is raised to 273 C and the pressure remains constant, the new volume of the gas will be 1) 1.25 L 3) 5.0 L 2) 2.5 L 4) 10. L 15. Which changes in pressure and temperature occur as a given mass of gas at 50.6 kpa and 546 K is changed to STP? 1) The pressure is doubled and the temperature is halved. 2) The pressure is halved and the temperature is doubled. 3) Both the pressure and the temperature are doubled. 4) Both the pressure and the temperature are halved. Gas Law Practice 16. The volume of a sample of a gas at273 C is 200. liters. If the volume is decreased to 100. liters at constant pressure, what will be the new temperature of the gas? 1) OK 3) 273 K 2) 100. K 4) 546 K 17. What volume will a 300.-milliliter sample of a gas at STP occupy when the pressure is doubled at constant temperature? 1) 150. ml 3) 300. ml 2) 450. ml 4) 600. ml 18. A sample of oxygen gas in a closed system has a volume of 200 milliliters at 600 K. If the pressure is held constant and the temperature is lowered to 300 K, the new volume of the gas will be 1) 100ml 3) 300ml 2) 200ml 4) 400ml 19. A gas sample has a volume of 25.0 milliliters at a pressure of 1.00 atmosphere. If the volume increases to 50.0 milliliters and the temperature remains constant, the new pressure will be 1) l.ooatm 3) atm 2) 2.00 atm 4) atm 20. At constant temperature, the relationship between the volume (V) of a given mass of gas and its pressure (P) is 1) V=kP 3) 2) 18

19 Name Ms. Tintella Review I. Base your answers to the question below on your knowledge of chemistry and the graph below: Date Regents Chemistry The graph shows the relationship between volume and absolute temperature for an ideal gas and two real gases, helium and oxygen. 0> o > KEY Ideal Gas Helium Oxygen 4 90 Temperature (K) a Describe the relationship for the ideal gas shown in this graph. b According to the graph above, what experimental condition is necessary for real gases to behave like an ideal gas? c At 90 K what happens to oxygen? d Why does helium behave more like an ideal gas than does oxygen? a) A direct relationship beiween the volume of a gas and it's absolute temperature, b) High temperatures, c) It changes to a liquid at its boiling point, d) The intermolecular forces between helium molecules is less than those between oxygen molecules. 2, Four identical balloons contain equal volumes of gas at STP: Balloon #1 contains H2 gas Balloon #2 contains He gas Balloon #3 contains O2 gas Balloon #4 contains N2 gas a Which balloon, if any would weigh the most? Explain. b According to the Kinetic Molecular Theory, why would the balloons expand if they were heated? 19

20 Vapor Pressure M-' 1 LJ i j r I"* Vapor Pressure Vapor (gas) exerts a pressure on all sides of a container. Look at Table H Observe trend: Looks at vapor pressure of water at 25, 50 & 70C What is the vapor pressure? Look at Table A Any substance boils when vapor pressure = atmospheric pressure. 20

21 ': Form WS6.3.3B PHASES OF MATTER Name Date Period An open glass of water left standing around will eventually evaporate even with out being heated. When water evaporates, it changes from a liquid to a gas called water vapor. Water vapor takes up more space than an equal mass of liquid water. As a result, in a closed container, the vapor that forms can exert a significant amount of s pressure. This pressure is known as vapor pressure. Even in an open container, the /- vapor is confined by the air pressing down on it. Some of it collects at the surface and exerts pressure. Occasional high energy molecules at the water's surface escape. That is why the water eventually evaporates. But for a water to expand and form vapor bubbles throughout the liquid as it does when it boils, the vapor has to exert as much pressure as the blanket of air confining it. As a liquid is heated, more of it turns into vapor, and the vapor pressure increases. When the vapor pressure reaches atmospheric pressure, the liquid boils. Under greater external pressure, the liquid boils at a higher temperature. The graph below shows the vapor pressures of four common liquids as a function of temperature. Refer to the graph to answer the questions that follow. 1. Which of the substances above has the lowest boiling point? 2. Which of the substances above has a boiling point of 100 C? 200 Vapor Pressure of Four Liquids 3. Which of the substances above has the highest boiling point? "3" o_ Which of the substances above has ~ the highest vapor pressure at $ 40 C? Which of the substances above J- will boil at 79 C? 6. At what temperature will alcohol boil when the atmospheric pressure is 50 kpa? 7. At what atmospheric pressure will propanone boil at 20 C? 8. At what atmospheric pressure will water boil at 90DC? Temoerature ( C) 9. Which of the substances above has the lowest vapor pressure at 70 C? 10. As the pressure decreases, the boiling point of water (a) increases, (b) decreases, (c) remains the same. 11. What is the vapor pressure of water at 60 C? Evan P. Silberstein,

22 VAPOR PRESSURE AND BOILING Name A liquid will boil when Its vapor pressure equals atmospheric pressure. Answer the questions following the graph. A B C Temperature C 1. At what temperature would Liquid A boil at an atmospheric pressure of 400 torr?. 2. Liquid B? 3. Liquid C? 4. How low must the atmospheric pressure be for Liquid A to boil at 35 C? 5. Liquid B? ^ 6. Liquid C? 7. What is the normal boiling point of Liquid A? 8. Liquid B? 9. Liquid C? ilnr 22

23 Name Ms. Tintella _1. Which substance has the lowest vapor pressure at 75 C? (1) water (3) propanone (2) ethanoic acid (4) ethanol _2. Using your knowledge of chemistry and the information in Reference Table ff, which statement concerning propanone and water at 50 C is true? (1) Propanone has a higher vapor pressure and stronger interniolecular forces than water. (2) Propanone has a higher vapor pressure and weaker intermolecular forces than water. (3) Propanone has a lower vapor pressure and stronger intermolecular forces than water. (4) Propanone has a lower vapor pressure and weaker intermolecular forces than water. 3. According to Reference Table H, what is the vapor pressure of propanone at 45 C? (1) 22 kpa (3) 70 kpa (2)33kPa (4)98kPa Vapor Pressure Date Regents Chemistry _8. The graph below shows the relationship between vapor pressure'and temperature for substance X. 2 8 I t a n ^ X / > Temperature (DC) What is the normal boiling point for substance (1) 50 C (2) 20 C / 1 (3) 30 C (4) 40 C _9. Which graph best represents the variation in the vapor pressure of water as temperature changes? 4. As the temperature of a liquid increases, its vapor pressure (1) decreases (3) remains the same (2) increases _5. Based on Reference Table H, which sample - has the highest vapor pressure? (1) water at 20 C (3) ethanol at 50 C (2) water at 80 C (4) ethanol at 65 C "NJ O a. n Si «a) Temperature Temperature _6. When the vapor pressure of water is 30 kpa, the temperature of the water is (1) 20 C (3) 70 C (2) 40 C (4) 100 C Vapo Temperature Temperature _1. Which sample of water will have the highest vapor pressure? (1)!O.Omlat62 C (3) 30.0 ml at42 C (2) 20.0 ml at 52 C (4) 40.0 ml at 32 C 23

24 _10. The graph below represents the vapor curves of four liquids. 800-, A -i 1 1 i i i r Temperature ( C) Which liquid has the highest normal boiling point? (1) A (3) C (2) B (4) D 24

25 Name Ms. Tintella 1. The kinetic molecular theory assumes that the particles of an ideal gas 1) are in random, constant, straight-line motion 2) are arranged in a regular geometric pattern 3) have strong attractive forces between them 4) have collisions that result in the system losing energy 2. Under which conditions does a real gas behave most like an ideal gas? 1) at low temperatures and high pressures 2) at low temperatures and low pressures 3) at high temperatures and high pressures 4) at high temperatures and low pressures Gas Laws Date Regents Chemistry Which 5.0-miIIiliter sample of NH3 will take the shape of and completely fill a closed milliliter container? 1) NH3(s) 3) NH3(g) 2) NH3(0 4) NH3(aq) According to the kinetic theory of gases, which assumption is correct? 1) Gas particles strongly attract each other. 2) Gas particles travel in curved paths. 3) The volume of gas particles prevents random motion. 4) Energy may be transferred between colliding particles. 3. Which statement correctly describes a sample of gas confined in a sealed container? 1) It always has a definite volume, and it takes the shape of the container. 2) It takes the shape and the volume of any container in which it is confined. 3) It has a crystalline structure. 4) It consists of particles arranged in a regular geometric pattern. 4. Which graph shows the pressure-temperature relationship expected for an ideal gas? QJ JL 3) 7. A real gas differs from an ideal gas because the molecules of real gas have 1) some volume and no attraction for each other 2) some volume and some attraction for each other 3) no volume and no attraction for each other 4) no volume and some attraction for each other 8. Under the same conditions of temperature and pressure, which of the following gases would behave most like an ideal gas? 1) He(g) 3) Cl2(g) 2) NH3(g) 4) C02(g) Temperature Temperature 9. One reason that a real gas deviates from an ideal gas is that the molecules of the real gas have 1) a straight-line motion 2) no net loss of energy on collision 3) a negligible volume 4) forces of attraction for each other Temperature 3 V) Cft QJ ol Temperature 10. Under which conditions of temperature and pressure would a sample of H2(g) behave most like an ideal gas? 1) 0 CandlOOkPa 3) 150 C and 100 kpa 2) 0 Cand300kPa 4) 150 C and 300 kpa 25

26 11. At the same temperature and pressure, 1.0 liter ofco(g)and 1.0 liter of C02(g) have 1) equal masses and the same number of molecules 2) different masses and a different number of molecules 3) equal volumes and the same number of molecules 4) different volumes and a different number of molecules 12. Each stoppered flask below contains 2 liters of a gas at STP. Each gas sample has the same 1) density 2) mass 3) number of molecules 4) number of atom's 15. As the temperature of a gas increases with the volume remaining constant, the pressure of the gas 1) decreases 3) remains the same 2) increases 16. A sample of a gas has a volume of 40. milliliters at 76.0 kpa. What will be the new volume of the gas if the pressure is increased to 80.0 kpa, temperature remaining constant? 1) 80ml. 3) 38ml 2) 42ml 4) 20ml 17. As the pressure of a gas at 150 kpa is changed to 100 kpa at constant temperature, the volume of the gas 1) decreases 3) remains the same 2) increases 18. Which graph represents the relationship between volume and Kelvin temperature for an ideal gas at constant pressure? 3) 13. A 10.-liter flask at a given temperature and pressure contains 6.0 x 1023 molecules of hydrogen gas. Under the same conditions of temperature and pressure, how many molecules would a 10.-liter flask of nitrogen gas contain? 1) 1.0 x ) 6.0 x ) 1.0 x JO24 4) 6.0 x ) Temperature Temperature Temperature Temperature 14. A sample of oxygen gas has a volume of 150. milliliters at 300 K. If the pressure of the sample is held constant and the temperature is raised to 600 K, the new volume of the sample will be 1) 75.0ml 3) 300. ml 2) 150. ml 4) 600. ml 19. The pressure on 20 milliliters of a gas at constant temperature is changed from 4 atmospheres to 2 atmospheres. The new volume of the gas is 1) 5ml 3) 40ml 2) 10ml 4) 80ml 26

27 20. When the pressure exerted on a confined gas at constant temperature is doubled, the volume of the gas is 1) halved 3) tripled 2) doubled 4) quartered 26. The graph below represents the uniform cooling of a substance, starting with the substance as a gas above its boiling point. 21. The volume of a sample of a gas is 1.0 liter at STP. If the pressure remains constant and the temperature is raised to 546 K, the new volume of the gas will be 1) 0.25 L 3) 0.50 L 2) 2.0 L 4) 4.0 L 22. Compared to a 1 mole sample of hydrogen at 273 K and 1 atmosphere, a 1 mole sample of hydrogen at 298 K and 1 atmosphere contains 1) more molecules 2) fewer molecules 3) molecules having higher average kinetic energy 4) molecules havirmjowelayeragejciaetic energy 23. The volume of a sample of a gas at 0 C is 100 liters. If the volume of the gas is increased to 200 liters at constant pressure, what is the new temperature of the gas in degrees Kelvin? 1) OK 3) 100 K 2) 273 K 4) 546 K 24. A sample of gas occupies 15.0 liters at a pressure of 2.00 atmospheres and a temperature of 300. K. If the pressure is lowered to 1.00 atmosphere and the temperature is raised to 400. K, the volume of the gas sample would be 1) 5.63 L 3) 22.5 L 2) 10.0L 4) 40.0 L 25. At constant pressure, what temperature must be reached to increase a 100,-milliliter sample of a gas initially at 300. K to a volume of 200. milliliters? 1) 150. K 3) 300. K 2) 200. K 4) 600. K C Time During which interval is the substance completely in the liquid phase? 1) AB 3) CD 2) BC 4) DE 27. Which physical changes are endothermic? 1) melting and freezing 2) melting and evaporating 3) condensation and sublimation 4) condensation and deposition 28. What is the total number of kilojoules of heat needed to change 150. grams of ice to water at 0 C? 1) ) 184 2) ) How much energy is required to vaporize grams of water at its boiling point? 1) 2.26 kj 3) 4.2 kj 2) 3.34 kj 4) 22.6 kj 30. What is the total number of Joules of heat energy absorbed by 15 grams of water when it is heated from 3 0. C to 40. C? 1) 42J 3) I30J 2) 63 J 4) 630 J 27

28 Ms. Tintella Gas Laws Regents Chemistry 1. Base your answer to the following question on the information below. Air bags are an important safety feature in modern automobiles. An air bag is inflated in milliseconds by the explosive decomposition of NaN3(s). The decomposition reaction produces (g), as well as Na(s), according to the unbalanced equation below. When the air bag inflates, the nitrogen gas is at a pressure of 1.30 atmospheres, a temperature of 301 K, and has a volume of 40.0 liters. Calculate the volume of the nitrogen gas at STP. Your response must include both a correct numerical setup and the calculated volume 2. Base your answer to the following question on the information below. A lightbulb contains argon gas at a temperature of 295 K and at a pressure of 75 kilopascals. The lightbulb is switched on, and after 30 minutes its temperature is 418 K. Show a correct numerical setup for calculating the pressure of the gas inside the lightbulb at 418 K. Assume the volume of the lightbulb remains constant. Base your answers to questions 4 and 5 on the diagram below, which shows, a piston confining a gas in a cylinder. 4, The gas volume in the cylinder is 6.2 milliliters and its pressure is 1.4 atmospheres. The piston is then pushed in until the gas volume is 3.1 milliliters while the temperature remains constant. a Calculate the pressure, in atmospheres, after the change in volume. Show all work. b Record your answer. 3. What is the total amount of heat energy, in joules, absorbed by 25.0 grams of water when the temperature of the water increases from 24.0 Cto36.0 C? 5. Sketch the general relationship between the pressure and the volume of an ideal gas at constant temperature. 28

29 Base your answers to questions 6 through 9 on the information below. A weather balloon has a volume of 52.5 liters at a temperature of 295 EC. The balloon is released and rises to an altitude where the temperature is 252 K. 6. What pressure, in atmospheres (atm), is equal to 45.6 kpa? 7. What Celsius temperature is equal to 252 K? 8. How does this temperature change affect the gas particle motion? The original pressure at 295 K was kpa and the pressure at the higher altitude at 252 K is 45.6 kpa. Assume the balloon does not burst. Show a correct numerical setup for calculating the volume of the balloon at the higher altitude. 29