30 january 2012 objective: you will be able to: review and discuss answers to the midterm exam
TRANSCRIPT
![Page 1: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/1.jpg)
30 January 2012
Objective: You will be able to: review and discuss answers to the
midterm exam.
![Page 2: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/2.jpg)
Agenda
Objective and Agenda Opportunities Midterm exam answers and
discussionHomework: Read p. 174-194Tomorrow: Gases!
![Page 3: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/3.jpg)
Field Trip Opportunity
Novartis is a biotech company in Cambridge that aims to discover, develop and successfully market innovative products to prevent and cure diseases, to ease suffering and to enhance the quality of life.
Tour, learn about what scientists at Novartis does, learn about biotech careers
Wednesday, February 15 periods 1-4
![Page 4: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/4.jpg)
Remember this?
![Page 5: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/5.jpg)
Harvard Museum of Natural History
Exhibit: The Language of Color Why do we see the colors we see?
Why does a blue butterfly look blue?
Why does a blue fish look blue?
![Page 6: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/6.jpg)
Exam Review/Answers
![Page 7: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/7.jpg)
Please be sure to return all parts of your midterm.
![Page 8: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/8.jpg)
![Page 9: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/9.jpg)
31 January 2012
Objective: You will be able to: describe and convert to standard
units for temperature and pressure use the Gas Laws to make
calculations for pressure, temperature, volume and number of moles of a gas.
![Page 10: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/10.jpg)
Gases
![Page 11: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/11.jpg)
Gases Topics
1. Definitions2. The Gas Laws3. The Ideal Gas Equation4. Gas Mixtures and Partial Pressures5. Kinetic Molecular Theory of Gases6. Effusion and Diffusion7. Real Gases Deviate from Ideal
Behavior
![Page 12: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/12.jpg)
Definitions
Pressure: the force that acts on a given area. Gases exert a pressure on any surface
they contact.http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/gasesv6.swf Standard pressure (at sea level): 1.01x105 Pascals = 101 kPa = 1 atm = 760 mm Hg = 760 torr
![Page 13: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/13.jpg)
Standard Temperature: 0oC = 273 Kelvin
Standard Temperature and Pressure =
1 atm and 0oC.
![Page 14: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/14.jpg)
The Gas Laws
2
22
1
11
T
VP
T
VP
Relate the pressure (P, atm), volume (V, liters) and temperature (T, Kelvin) of a sample of gas
http://phet.colorado.edu/en/simulation/gas-properties
![Page 15: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/15.jpg)
If you hold T constant…
Boyle’s Law: P1V1=P2V2
![Page 16: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/16.jpg)
Boyle’s Law
If the pressure of a fixed amount of gas doubles at a constant temperature, what happens to its volume?
![Page 17: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/17.jpg)
If you hold P constant…
Charles’ Law:
2
2
1
1
T
V
T
V
![Page 18: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/18.jpg)
Charles’ Law
When the temperature of a fixed amount of gas doubles from 20oC to 40oC, what happens to the volume at constant pressure?
![Page 19: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/19.jpg)
Avogadro’s Hypothesis Equal volumes of gases under the same
conditions of temperature and pressure contain equal numbers of molecules
a mole of gas at STP has a volume of 22.4 L
![Page 20: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/20.jpg)
Avogadro’s Law
The volume of a gas at constant temperature and pressure is directly proportional to the number of moles of the gas
The coefficients in a balanced equation can be taken as ratios of moles or liters at constant T and P
2
2
1
1
n
V
n
V
![Page 21: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/21.jpg)
Example 1
How many liters of water vapor can be obtained from the complete combustion of 24 liters of methane gas? Assume constant temperature and pressure and water in the gas phase.
![Page 22: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/22.jpg)
Example 2
A weather balloon on the ground contains 25.8 L of He at 29.0oC and 741 torr. What is the volume of the balloon when it rises to an altitude where the temperature is 11.0oC and the pressure is 535 torr?
![Page 23: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/23.jpg)
Problem 1
The gas pressure in an aerosol can is 1.5 atm at 25oC. Assuming that the gas inside is an ideal gas, what would the pressure be if the can were heated to 450oC.
![Page 24: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/24.jpg)
Problem 2
A large natural gas storage tank is arranged so that the pressure is maintained at 2.20 atm. On a cold day in December when the temperature is -15oC (4oF), the volume of gas in the tank is 3.25x103 m3. What is the volume of the same quantity of gas on a warm July day when the temperature is 31oC (88oF)?
![Page 25: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/25.jpg)
The Ideal Gas Equation
Combines Boyle’s, Charles’ and Avogadro’s Laws
PV=nRT
P = V = n = T = R =
![Page 26: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/26.jpg)
ideal gas: a hypothetical gas whose pressure, volume and temperature behavior is completely described by the ideal gas equation no gas is an ideal gas all gases are “real” gases but most gases, above 25oC and
below 1 atm, behave like ideal gases
![Page 27: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/27.jpg)
p. 216 #16, 19, 21, 23, 31, 33
![Page 28: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/28.jpg)
1 February 2012
Take Out Homework Objective: You will be able to:
use the ideal gas equation to solve for the pressure, volume, temperature or number of moles of a gas.
Homework Quiz: The volume of a gas is 5.80 L, measured at 1.00 atm. What is the pressure of the gas in mmHg if the volume is changed to 9.65 L? Temperature remains constant.
![Page 29: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/29.jpg)
Agenda
I. Homework QuizII. Homework answersIII. Using the Ideal Gas EquationIV. Partial PressureV. Molar volume of gas lab
introductionHomework: p. 217 #35, 37, 39, 41,
51, 53 – Mon., read lab and do pre-lab questions in lab notebook - tomorrow
![Page 30: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/30.jpg)
Using the Ideal Gas Equation
Example 1Gasoline is a mixture of many
hydrocarbon compounds but its chemical formula can be approximated as C8H18. How many liters of carbon dioxide gas are formed at 25.0oC and 712 torr when 1.00 gallon of liquid gasoline is burned in excess air? Liquid gasoline has a density of 0.690 g/mL. One gallon = 3.80 L
![Page 31: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/31.jpg)
Problem 3
Calcium carbonate, CaCO3(s), decomposes upon heating to give CaO(s) and CO2(g). A sample of CaCO3 is decomposed, and the carbon dioxide is collected in a 250-mL flask. After the decomposition is complete, the gas has a pressure of 1.3 atm at a temperature of 31oC. How many moles of CO2 were generated?
![Page 32: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/32.jpg)
Problem 4
Tennis balls are usually filled with air or N2 gas to a pressure above atmospheric pressure to increase their “bounce.” If a particular tennis ball has a volume of 144 cm3 and contains 0.33 g of N2 gas, what is the pressure inside the ball at 24oC?
![Page 33: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/33.jpg)
6 February 2012
Objective: You will be able to: calculate the density of a gas describe kinetic molecular theory define effusion and diffusion
Homework Quiz: Methane, CH4, the principal component of natural gas, is used for heating and cooking. If 10.0 moles of methane are reacted, what is the volume of CO2, in liters, produced at 23.0oC and 0.985 atm?
![Page 34: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/34.jpg)
Agenda
I. Homework QuizII. Homework answersIII. Density calculationsIV. Partial pressuresV. Kinetic-Molecular theoryVI. Effusion and DiffusionHomework: p. 218 #63, 65, 67, 69, 71,
93, 95
![Page 35: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/35.jpg)
Example
What is the density of sulfur dioxide gas at 35oC and 1270 torr?
![Page 36: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/36.jpg)
Problem 5
What is the density of carbon tetrachloride vapor at 714 torr and 125oC?
![Page 37: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/37.jpg)
Problem 6
A series of measurements are made to determine the molar mass of an unknown gas. First, a large flask is evacuated and found to weight 134.567 g. It is then filled with the gas to a pressure of 735 torr at 31oC and reweighed. Its mass is now 137.456 g. Finally, the flask is filled with water at 31oC and found to weigh 1067.9 g. Calculate the molar mass of the unknown gas.
(The density of the water at this temperature is 0.997 g/mL)
![Page 38: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/38.jpg)
Gas Mixtures and Partial Pressures
partial pressure: the pressure exerted by an individual gas in a mixture of gases
Dalton’s Law of Partial Pressures: the total pressure of a mixture of gases is the sum of the pressures that each gas would exert if it were present alone.
Ptotal = P1 + P2 + P3 + …
![Page 39: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/39.jpg)
mole fraction: the ratio of moles of one gas to the total moles of gas in a mixture
X1 = n1/nt
Each gas in a mixture behaves independently of all the other gases in the mixture and obeys the ideal gas law.
![Page 40: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/40.jpg)
Example 1
A mixture of 9.00 g oxygen, 18.0 g argon and 25.0 g of carbon dioxide exerts a pressure of 2.54 atm. What is the partial pressure of argon in the mixture?
![Page 41: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/41.jpg)
2 February 2012
Objective: You will be able to: determine the molar volume of a
gas by generating and measuring hydrogen gas, and using the gas laws.
Do now: Grab a pair of goggles
![Page 42: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/42.jpg)
Agenda
I. ObjectiveII. Pre-lab questionsIII. Lab directionsIV. Do the lab!V. Collect and analyze dataVI. Post lab questionsHomework: Book work assigned
yesterdayLab notebook: due Monday
![Page 43: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/43.jpg)
Molar Volume of a Gas Lab
Weight your 3 cm piece of magnesium instead of calculating the mass.
Follow the directions carefully! Leave the HCl at the front – bring
your graduated cylinder. Use the 1000 mL graduated cylinder
for step 15. We only have one. Take turns.
Barometric pressure = 30.03 in Hg now
![Page 44: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/44.jpg)
p. 7 #7:
graduated cylinder eudiometer
![Page 45: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/45.jpg)
Your lab notebook1. Name, etc. on top.2. Purpose3. Pre-lab questions4. Procedure summary5. Data organized into a table or along with
procedure6. Calculations, including units and labels
describing what the calculation is!7. Answer to post lab questions8. One more source of error and specifically
how it affects your data. How would you correct it?
![Page 46: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/46.jpg)
Problem 7
A gaseous mixture made from 6.00 g O2 and 9.00 g CH4 is placed in a 15.0 L vessel at 0oC. What is the partial pressure of each gas, and what is the total pressure in the vessel?
![Page 47: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/47.jpg)
7 February 2012
Objective: You will be able to: describe the Kinetic Molecular theory of
gases describe effusion and diffusion and calculate
effusion rate Homework Quiz:a. What is the mass of the solid NH4Cl formed
when 73.0 g of NH3 gas are mixed with an equal mass of HCl gas?
b. What is the volume of the gas remaining, measured at 14.0oC and 752 mmHg? Which gas is it (NH3 or HCl)?
![Page 48: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/48.jpg)
Homework p. 219 #76, 93, 101, 103, 105, 106, 132
![Page 49: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/49.jpg)
Problem 8
What is the total pressure exerted by a mixture of 2.00 g of H2 and 8.00 g of N2 at 273 K in a 10.0 L vessel?
![Page 50: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/50.jpg)
Problem 9
A study of the effects of certain gases on plant growth requires a synthetic atmosphere composed of 1.5 mol percent CO2, 18.0 mol percent O2 and 80.5 mol percent Ar.
a. Calculate the partial pressure of O2 in the mixture if the total pressure of the atmosphere is 745 torr.
b. If this atmosphere is to be held in a 121 L space at 295 K, how many moles of O2 are needed?
![Page 51: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/51.jpg)
Kinetic Molecular Theory a model that explains the macroscopic behavior of
gases at the atomic and molecular level.1. Gases consist of atoms or molecules in
continuous, random motion2. The volume of the gas particles is negligible
relative to the volume of their container3. Attractive and repulsive forces between gas
particles are negligible.4. Collisions between gas particles and between gas
particles and the walls of their container are perfectly elastic (no energy is lost)
5. The average kinetic energy of the particles is proportional to the absolute temperature.
![Page 52: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/52.jpg)
Problem 10
Use kinetic molecular theory to explain why, when the temperature of a fixed volume of gas increases, the pressure increases.
![Page 53: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/53.jpg)
Problem 11 A sample of O2 gas initially at STP is
compressed into a smaller volume at constant temperature. What effect does this change have on:
a. the average kinetic energy of O2 molecules?
b. the average speed of O2 molecules?
c. the total number of collisions of O2 molecules with the container walls in a unit time?
d. the number of collisions of O2 molecules with a unit area of container wall per unit time?
![Page 54: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/54.jpg)
8 February 2012 Objective: You will be able to:
describe effusion and diffusion and calculate effusion rate.
Homework Quiz: a. A mixture of gases contains 4.46
moles of neon and 0.74 moles of argon. Calculate the partial pressures of the gases if the total pressure is 2.00 atm at a certain temperature.
b. Calculate the volume occupied by the argon gas at 0oC.
![Page 55: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/55.jpg)
Agenda
I. Homework quizII. Homework answersIII. Effusion and DiffusionIV. Diffusion demo and videoHomework: Gases problem set: Mon.
![Page 56: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/56.jpg)
Effusion and Diffusion Effusion: the escape of gas molecules
through a tiny hole into an evacuated space.
Diffusion: the spread of one substance through space or through another substance.
Graham’s Law of Effusion: the effusion rate of a gas is inversely proportional to the square root of its molar mass. the equation relates the ratio of effusion
rates of two gases:2
1
1
2
2
1
M
M
r
r
![Page 57: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/57.jpg)
http://www.youtube.com/watch?v=WAJAslkwolk
![Page 58: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/58.jpg)
Example
At a particular temperature and pressure, neon gas effuses at a rate of 16.0 mol/s.
a. What is the rate at which argon effuses under the same conditions?
b. Under a different set of conditions, 3.0 mol of argon effuse in 49.0 seconds. How long will it take an equal amount of helium to effuse?
![Page 59: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/59.jpg)
9 February 2012
Objective: You will be able to practice gas unit objectives and calculations.
Homework Quiz: A gas of unknown molecular mass was allowed to effuse through a small opening under 2.0 atm and 20oC. It required 105 s for 1.0 L of the gas to effuse. Under identical conditions, it required 31 s for the same amount of O2 gas to effuse. Calculate the molar mass of the unknown gas.
![Page 60: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/60.jpg)
Problem 12
An unknown gas composed of homonuclear diatomic molecules effuses at a rate that is only 0.355 times that of O2 at the same temperature. Calculate the molar mass of the unknown and identify it.
![Page 61: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/61.jpg)
Real Gases: Deviations from Ideal Behavior
Real gas particles have volume! Real gas particles have attractive and
repulsive forces between them! Especially at high pressure and low
temperature, real gases do not be have ideally.
Deviation from ideal behavior increases with increasing complexity and mass of a molecule of a gas.
![Page 62: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/62.jpg)
Problem 13
Which of the noble gases will deviate most from ideal behavior? Why?
Arrange the following in order of increasing deviation from ideality:H2O(g), CH4(g), Ne
Justify your answer
![Page 63: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/63.jpg)
Problem Set Work Time
30 minutes: independently Then, with a partner Why?
If you’ve never tried problems independently before a test…
The fewer brains, the more yours works
![Page 64: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/64.jpg)
Homework
Problem Set: due Monday Gases Unit Test Tuesday
10 MC 1 multi-part free response question
Review session: tomorrow 3:20-4:15 in 205
![Page 65: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/65.jpg)
What weapon can you make from potassium, nickel and iron?
![Page 66: 30 January 2012 Objective: You will be able to: review and discuss answers to the midterm exam](https://reader035.vdocuments.mx/reader035/viewer/2022062321/56649dc55503460f94ab8be3/html5/thumbnails/66.jpg)
14 February 2012
Take Out: Periodic table and calculator
Objective: You will be able to: show what you know about gases!