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Gas Relationships

Gas Relationships. Luke, I am your farter…. Shoe lab results. How is pressure related to force and area? Complete these sentences If the forces stays the same and the area decreases, what happens to the pressure? Increases

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Gas Relationships

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  1. Gas Relationships Luke, I am your farter…..

  2. Shoe lab results How is pressure related to force and area? Complete these sentences • If the forces stays the same and the area decreases, what happens to the pressure? Increases • If the pressure stays the same and the area decreases, what happened to the force? Force decreased

  3. Answer in terms of pressure, area and force • Your grandparents just installed a new wood floor but they don’t want your sister to walk across it in her high heel shoes. Why not? • Someone throws a quarter to the bottom of the deep end of the swimming pool. You dive down for it and your ears start to hurt when you get to the bottom. Why?

  4. Pressure conversions Conversion factors you should know: 1 atmosphere(atm) = 101.3 kPa = 760mmHg = 14.7 psi =760 torr Convert the following 6 atm is equal to _______ a. mm Hg _______ b. kPa _______ c. psi 300 kPa = _______ a. mm Hg _______ b. atm _______ c. psi

  5. Pressure conversions Conversion factors you should know: 1 atmosphere(atm) = 101.3 kPa = 760mmHg = 14.7 psi Convert the following 6 atm is equal to 4560 a. mm Hg 607.8 b. kPa 88.2 c. psi 300 kPa = 2250 a. mm Hg 2.96 b. atm 43.5 c. psi

  6. Pressure and Volume What is the relationship between pressure and volume? Inverse relationship: when one increases the other decreases What two quantities are staying constant? Temperature and amount of gas This relationship is known as Boyles’ Law

  7. PV=k So P1V1 = P2V2

  8. Pressure Volume problems • A gas is at 101.3 kPa and has volume of 2 L. What will the new volume be if the pressure is increased to 202.6 kPa? • A gas occupies a volume of 4 L at a pressure of 100 kPa. At what pressure will the volume be 8L? • If the pressure is 25 kPa and the volume 6L, what will the new volume be when the pressure is 75 kPa?

  9. Pressure Volume problems • A gas is at 101.3 kPa and has volume of 2 L. What will the new volume be if the pressure is increased to 202.6 kPa? 1 L • A gas occupies a volume of 4 L at a pressure of 100 kPa. At what pressure will the volume be 8 L? 50 kPa • If the pressure is 25 kPa and the volume 6 L, what will the new volume be when the pressure is 75 kPa? 2 L

  10. Volume and Temperature Consider the hot plate and balloon What is the relationship between temperature and volume? Direct relationship: as temperature increases, volume increases What quantities are staying the same? Pressure and amount of gas This relationship is known as Charles’ Law

  11. V/T = k The relationship is true as long at you remember to express temp. in Kelvin K=oC+273 oC=K-273 *rather have a C+ than a K- on my report card relationship known as Charles’ Law

  12. Charles’ Law practice • At 200 K the volume of a gas is 2 L, what will the volume be when the temperature is 100 K? 1 L • A gas at 30oC that occupies a volume of 2 L is heated til the temperature is 60oC, what is the new volume? 2.2 L • The temperature of a gas is 273oC and it occupies a volume of 4 L. What is the temperature in oC when it occupies a volume of 8 L? 819oC

  13. Pressure and Temperature If you throw an aerosol can into a fire what happens to the Temperature of the gas in the can? The pressure of the gas in the can? What is likely to happen? http://www.clipaday.com/dl.php?mediaurl=aerosol-can-explosion What is the relationship between pressure and temperature? How must temperature be treated in any gas problem?

  14. Gay-Lussac’s Law

  15. Combined gas law T must be in Kelvin

  16. Combined gas law practice • A gas has a volume of 2 L at a temperature of 100 K and a pressure of 200 kPa. What is the new volume when the pressure is at 4 L and the temperature is 50 K? 50 kPa 2. A gas has a volume of 4 L at a temperature of 200 K and pressure of 3 atmospheres. If the pressure is doubled and the Kelvin temperature is halved, what will be the new volume? I L

  17. Quiz up to combined gas law • A sample of helium gas has a volume of 200.0 mL at 0.960 atm. What pressure, in atm, is needed to reduce the volume at a constant temperature to 50.0 mL? • A sample of nitrogen gas occupies 1.55 L at 27.0oC and 1.00 atm. What will the volume be at -100.0oC and the same pressure? • A gas occupies 2.0 m3 ata 100.0 K and exerts a pressure of 100.0 kPa. What volume will the gas occupy if the temperature is increased to 400.0 K and the pressure is increased to 200.0 kPa?

  18. Quiz up to combined gas law • A sample of helium gas has a volume of 200.0 mL at 0.960 atm. What pressure, in atm, is needed to reduce the volume at a constant temperature to 50.0 mL? 3.84 atm • A sample of nitrogen gas occupies 1.55 L at 27.0oC and 1.00 atm. What will the volume be at -100.0oC and the same pressure? 0.894 L • A gas occupies 2.0 m3 ata 100.0 K and exerts a pressure of 100.0 kPa. What volume will the gas occupy if the temperature is increased to 400.0 K and the pressure is increased to 200.0 kPa? 4 L

  19. Gay Lussac’s law of combining volumes of gases At constant T and P, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers Coefficients in a balanced equation can represent Moles or Molecules or Volumes of a gas (if they are all under same conditions

  20. Avogadro’s law Equal volumes of gases at the same T and P contain equal numbers of molecules So….. 2 L of O2 at STP has the same number of molecules as 2 L He at STP 22.4 L of CO2 at STP has one mole of particles and 22.4 L of Ne at STP has one mole of particles

  21. 2C2H6(g)+ 7O2(g) 4CO2 (g)+ 6H2O(g) • One liter of ethane (C2H6) gas at will produce ___ Liters of carbon dioxide, if all gases are under the same conditions. • 28L of oxygen gas will react with ____ L of ethane, if all conditions are the same. • How many liters of water vapor can be produced if 5 L of ethane is burned?

  22. 2C2H6(g)+ 7O2(g) 4CO2 (g)+ 6H2O(g) • One liter of ethane (C2H6) gas at will produce ___ Liters of carbon dioxide, if all gases are under the same conditions. 2L • 28L of oxygen gas will react with ____ L of ethane, if all conditions are the same. 8 L • How many liters of water vapor can be produced if 5 L of ethane is burned? 15 L

  23. Ideal gas law In the other gas laws the amount of gas was always constant, only P or V or T changed. In the ideal gas law, the amount of gas is a variable also – an is represented by n, which stands for the number of moles. PV=nRT T must be in Kelvin and the value of R depends on the unit of pressure used – pay attention to this.

  24. R = ideal gas constant P = atm = R= 0.0821 P= mmHg = R = 62.4 P = kPa = R = 8.314

  25. Calculate the pressure, in atm, exerted by 2.50 L of HF containing 1.35 mol at 320 K. 14.2 atm Calculate the volume, in L, occupied by 2.00 mol H2 at 300 K and 1.25 atm. 39.4 L Determine the number of moles of gas contained in 1.25 L at 250.0 K and 1.06 atm. 0.065 mol Find the mass of 5.60 L O2 at 1.75 atm and 250.0 K. 15.3 g

  26. Calculate the pressure, in atm, exerted by 2.50 L of HF containing 1.35 mol at 320 K. Calculate the volume, in L, occupied by 2.00 mol H2 at 300 K and 1.25 atm. Determine the number of moles of gas contained in 1.25 L at 250.0 K and 1.06 atm. Find the mass of 5.60 L O2 at 1.75 atm and 250.0 K.

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