2 10 How Are P And T Related
- 1. Launch: 2/10 Grab your binder and immediately take a seat! Place launch paper on your desk. Yesterday’s Benchmark Data: 96%! Today’s Objectives: I can apply the gas laws to relations between temperature and pressure.
- 2. Launch 2/10 1. What is the equation for converting between the Celcius and Kelvin scales? Label the variables.
- 3. Launch 2/10 2. Molecules in a substance at 50°C a. move slower than molecules in a substance at 25°C because they have less kinetic energy b. move slower than molecules in a substance at 25°C because they have more kinetic energy c. move faster than molecules in a substance at 25°C because they have less kinetic energy d. move faster than molecules in a substance at 25°C because they have more kinetic energy
- 4. Launch 2/10 3. What is the equivalent of 423K in degrees Celsius? a. -223°C b. -23°C c. 150°C d. 696°C
- 5. Launch 2/10 4. Convert -50°C to Kelvin. a. -223 K b. -50 K c. 223 K d. 323 K
- 6. Announcements Great job yesterday! No quiz on Friday Class points end on Friday Only 3 days until break… Let’s finish strong
- 7. February Calendar Quiz! Today No quiz! Exam!
- 8. Opening Today’s Objective: I can apply the gas laws to relations between temperature and pressure. Standard – CH.4.c Today’s Questions: How are P and T related?
- 9. How are P & T related? Mr. Heffner 2/10/10
- 10. How are P & T related? Temperature is… a measure of movement °C & K Pressure is… a measure of random collisions atm & mmHg
- 11. How are P & T related? temperature = collisions = pressure temperature = pressure
- 12. How are P & T related? Pressure & Temperature are… directly related change in the same direction In math terms… P = constant T “some number”
- 13. How are P & T related? By rearranging the relationship, we can get an equation P1 P2 starting conditions T1 = constant = T ending conditions 2 P1 P2 = T1 T2
- 14. How are P & T related? There is a 3 step process for solving gas equations: 1. Write down the equation and given conditions 2. Plug in for the variables 3. Solve for the unknown
- 15. Example #1 At 298K (room temp), the pressure inside an empty Coke can is 1 atm. It is then thrown into a bucket of ice at 273K. What is the new gas pressure? Step 1: Write down the equation and given conditions P1 = 1 atm P1 P2 = T1 = 298K T1 T2 P2 = ? T2 = 273K
- 16. Example #1 At 298K (room temp), the pressure inside an empty Coke can is 1 atm. It is then thrown into a bucket of ice at 273K. What is the new gas pressure? Step 2: Plug in for the variables P1 = 1 atm 1 P1 atm P2 = T1 = 298K T1 T2 298K 273K P2 = ? T2 = 273K
- 17. Example #1 At 298K (room temp), the pressure inside an empty Coke can is 1 atm. It is then thrown into a bucket of ice at 273K. What is the new gas pressure? Step 3: Solve for the unknown cross- 1 atm P2 multiply = ✕ 298K 273K (P2)(298K) = (1 atm)(273K) 298K 298K P2 = .92 atm
- 18. Example #2 The pressure of oxygen gas at 300K is reduced to from 760mmHg to 380mmHg. What is the final temperature? Step 1: Write down the equation and given conditions P1 = 760 mmHg P1 P2 = T1 = 300K T1 T2 P2 = 380 mmHg T2 = ?
- 19. Example #2 The pressure of oxygen gas at 300K is reduced to from 760mmHg to 380mmHg. What is the final temperature? Step 2: Plug in for the variables P1 = 760 mmHg P1 P2P2 760mmHg 380mmHg = T1 = 300K T 300K 1 T2T? 2 P2 = 380mmHg T2 = ?
- 20. Example #2 The pressure of oxygen gas at 300K is reduced to from 760mmHg to 380mmHg. What is the final temperature? Step 3: Solve for the unknown 760mmHg 380mmHg 300K ✕= T2 1 (380mmHg)(300K) = (760mmHg)(T2) 760mmHg 760mmHg 2 150K = T2
- 21. Example #3 The pressure of Cl2 gas is 1 atm at 50K. What would the final pressure be if the temperature was raised to 100K? Step 1: Write down the equation and given conditions P1 = 1 atm P1 P2 = T1 = 50K T1 T2 P2 = ? T2 = 100K
- 22. Whiteboards Work in pairs Trade-off marker every question You have 60 seconds to calculate the answer Show all of your work! Don’t forget units! Lift board only when prompted
- 23. The temperature of a gas is raised by 50K. Draw an arrow (up/down) to show how pressure would be affected.
- 24. The pressure of a gas is lowered to .5 atm from STP . Draw an arrow showing what would happen to the temperature.
- 25. A gas is sealed in a bottle at 400K and 2 atm. If put into a freezer at 200K, what would the new pressure be?
- 26. The pressure of CH4 (methane) gas at 10K is increased from 2 atm to 10 atm. What is the new pressure?
- 27. Closing Today’s Objective: I can describe how the random collisions between gas molecules creates pressure on a surface. Standard – CH.4.a Molecular Motion Applet
- 28. Exit Slip 1. What is pressure? a. a force that comes from the interaction of molecules in a chemical bond b. the amount of kinetic energy in a substance c. a quantity that can be measured in mm d. the force that a gas exerts on an object
- 29. Exit Slip 2. Which of the following factors effect the force that is exerted on an object? # of gas molecular collisions temperature speed I II III a. I only b. II only c. II & III d. I, II and III
- 30. Exit Slip 3. Which of the following relationships is correct? a. an increase in temperature an increase in pressure b. a decrease in temperature an increase in kinetic energy c. an increase in temperature a decrease in pressure d. a decrease in temperature a increase in the number and speed of collisions
- 31. Exit Slip 4. A soccer ball is inflated to a certain pressure and is then heated in an oven. As it warms up the pressure increases because a. air molecules hit the walls of the ball less frequently b. rubber in the soccer ball reacts with the air inside the ball c. air molecules speed up and collide with the wall of the ball more often d. air molecules diffuse quickly out of the ball
- 32. Exit Slip 5. Would you expect a gas at 100°C to have a higher pressure than a gas at 0°C? a. No, because it has less kinetic energy b. No, because it has a higher temperature c. Yes, because it has more random collisions d. Yes, because it has less kinetic energy
- 33. Homework Finish practice questions Study for the quiz!