1 / 23

Homework 10 posted and due Friday 13 April

Dive into the world of gases with a metaphorical journey through atoms, moles, and reactions. Explore fundamental gas laws and their practical applications in pressure measurements. From familiar metaphors to solving combined gas law problems, this chemistry road trip will expand your understanding of gas behavior in exciting ways. Pack your bags and join the adventure!

pittselizabeth
Download Presentation

Homework 10 posted and due Friday 13 April

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Homework 10 posted and due Friday 13 April This week in lab: U-present atomic dimension metaphor (plus answers to 2 pre-lab questions)

  2. Metaphor 1: Old Yankee Stadium, the Bronx Atom dimensions in familiar terms. 3” Electrons start here (~2.4 miles past cheap seats) Baseball as nucleus

  3. Nucleus(+) ~ dimension of electronic cloud (-) (2.4 mile radius from baseball nucleus)

  4. Metaphor 2: POP CAN WITH STRING + PENCIL DOT… HOW FAR AWAY IS THE ELECTRON FROM THE PROTON (DOT) {0.02 CM DIAMETER}? Metaphor 3: CUT UP 20 cm STRIP OF PAPER…HOW MANY CUTS TO REACH ATOMIC SCALE? Answer: 50X

  5. Proton mass Metaphor 4: proton vs. electron mass Electron mass 0.0825 lbs (37 g) 165 lb running back=proton weighs ~ 2000 eggs

  6. Our Chemistry Road trip so far … Moles, molecules and reactions Molecules and Moles acting alone

  7. Next up: the Chemistry of the Crowd Chapter 5:Gases (pp. 189-230) an exploration of `aggregate’ behavior

  8. Pressure (P) concepts & measures in “Physics-speak “(see p 192) P = Force Area Physics speak P=newtons m2 Physics units =kg*m/s2 =kg m s2 m*m

  9. Pressure (P) concepts & measures in “Physics-speak“(see p 191)  1 kg = 1Pascal (Pa) m s2

  10. Some lowbrow chem insights into Pressure • Getting hammered • Bed of nails

  11. Pressure in `lowbrow’ Chem speak (continued): barometers ( see fig. 5.3, 5.4 of text) Evacuated space External atmospheric pressure, P P in mm Hg=760 A Torricelli barometer Hg

  12. in CHEMISTRY LAND Pressure units 1 atmosphere =760 mm Hg = 760 torr =29.92 inches Hg Other common measures of an atmosphere 1 atmosphere=10336 mm H2O =33.9 ft H2O = 20 miles of air = 15 pounds/in2 (psi)

  13. U-do-it P conversions 1 atmosphere =760 mm Hg = 760 torr =29.92 inches Hg = 15 pounds/in2 (psi) 28 inches Hg= atm 0.936 = torr 711 = psi 14.0

  14. Need more practice ???

  15. Physics Pressure units in PHYSICS COUNTRY Physics speak 1 atm = 101.3 kPa Confusing Compromise 1 bar =100 kPa= 0.986 atm WE ARE GOING TO STICK WITH ATMOSPHERES (atm) IN THIS COURSE

  16. Empiricgas law derivations:the common sense way What variables do we follow when describing a gas ??? P, T, V, n n P Tup  ?? Vup => T, V vary Tdown ?? Vdown CHARLES’ LAW (p. 195) V V = bT V1 = T1 V2T2 T V1/T1= V2/T2

  17. Empiricgas law derivations:the common sense way (cont.) nT Vdown ?? Pup => P, V vary Vup ??  Pdown P BOYLE’S LAW () P = k/V P1 = 1/V1 P21/V2 V P1V1=P2V2

  18. Empiricgas law derivations:the common sense way (cont.) n V Tup ?? Pup => T, P vary Tdown ?? Pdown P GAY-LUSSAC’S LAW (not in text) P = aT T in K T1= P1 T2P2 T P1/T1= P2/T2

  19. How Boyle, Gay-Lussac and Charles Laws are reflected in the Combined Gas Law (when n is constant) Gas Law Equation Conditions Name of Gas Law constant n P1V1 = P2 V2 T1 T2 Combined Gas Law constant n,P Charles’ Law (P1=P2) P1V1 = P2 V2 T1 T2 P1V1 = P2 V2 T1 T2 constant n, T Boyle’s Law (T1=T2) P1V1 = P2 V2 T1 T2 Gay-Lussac’s Law (V1=V2) constant n, V

  20. An ideal gas at constant V and P=2 atm is heated from 300 to 600 K. What is the final P ? • 1 atm • 2 atm • 3 atm • 4 atm

  21. COMBINED GAS LAW PROBLEMS…BOARD WORK • A sample of oxygen gas is expanded from 20 to 50 liters at constant temperature. The final pressure is 4 atm. What was the initial pressure ? P1=10 atm

  22. A sample of ideal gas arrives at 300K when expanded from 3 to 9 L at constant P. What was the original temperature ? • 900 K • 100 K • 600 K • 150 K

  23. COMBINED GAS LAW PROBLEMS…BOARD WORK (CONT.) 2. A child’s balloon originally occupies 5 liters at sea level (P=1 atm)and room temperature (300 K) . It is released and is allowed to riseto an altitude where the pressure is 0.25 atm and the temperatureis 150 K. What is the balloon’s new volume ? 10 L

More Related