BIG CHILL PROJECT 5% Goal: Build a container that keeps an ice
cube from melting for the longest period of time. 1. Must be 15.0cm
x 15.0cm x 15.0cm or smaller. 2. Must operate at room temperature
with no electricity. 3. Must be an original creation. Slide 2 BIG
CHILL PROJECT 4. Must have a opening and chamber big enough to
accommodate an ice cube. Slide 3 BIG CHILL PROJECT Grade is two
parts: 1. Construction - 50 pts 2. Efficiency - 50 pts Bonus points
for being a top three finisher in your class, the best design in
your class, ice cube lasting longer than 8 hours, and a parent
signature on the blue form. DUE THURSDAY MARCH 14 Slide 4
OBJECTIVES Describe the effect on a gas by a change in the amount
of gas (moles), the pressure of gas, the volume of gas, and the
temperature of gas. Be able to perform calculations using Boyles
Law, Charles Law, and Gay-Lussacs Law. Be able to use Daltons Law
of Partial Pressures in a calculation Distinguish between real and
ideal gases. Be able to tell how real gases differ from ideal
gases. State the ideal gas law and know what each symbol stands for
Perform calculations using the ideal gas law and the combined gas
law. State and use Grahams Law of Diffusion. Be able to calculate
gas stoichiometry problems (volume volume, mass volume, volume
mass). Be able to calculate density and molecular mass using the
ideal gas law formula. Slide 5 GAS LAWS Chapters 12-13 Slide 6
PRESSURE (Chapter 12) Pressure is the force per unit area. Gases
exert pressure when they hit the walls of their container. To
measure air pressure, you might use a barometer or a manometer. A
barometer measures atmospheric pressure. A manometer measures the
internal pressure of an enclosed gas. Slide 7 PRESSURE There is
pressure exerted by the atmosphere. At sea level this pressure is
equal to one atmosphere. Slide 8 PRESSURE DEMO Fig Newtons Slide 9
PRESSURE Pressure is measured in a variety of units.
UNITABBREVIATIONCOMPARE TO 1 ATM KilopascalkPa101.3 kPa Millimeters
of mercury mmHg760.0 mmHg Torrtorr760.0 torr Atmosphereatm1.0 atm
Pounds per square inch* psi14.7 psi *We will use all of these but
psi. Slide 10 VIDEODISC Chapter 2 Racing Hot Air Balloons 1. Why is
it easier for pilots to control the vertical direction of a
balloons flight than the horizontal direction? 2. Why did Julie say
that a thermal is not a good word for balloonists? Slide 11 GASES
(Chapter 12) Physical Properties of Gases: Gases have mass. Gas
particles do not attract or repel each other. It is easy to
compress gases. Gas molecules are in constant motion Gases fill
their containers completely Different gases can move through each
other quite rapidly. Gases exert pressure. The pressure of a gas
depends on its temperature and volume. Slide 12 GASES Remember that
gases consist of very small particles, the particles have large
distances between them, they are in constant, rapid, random motion
and have elastic collisions. Actual gases (in real life) do not
obey all the suppositions stated in the kinetic-molecular theory.
In order to accurately measure a gas sample, you must know the
quantity of particles (moles), pressure, temperature, and volume of
a gas. Slide 13 THE GAS LAWS (Chapter 13) 1. Boyles Law:V and P;
inversely proportional. 2. Charles Law: T and V; directly
proportional. 3. Gay-Lussacs Law: P and T; directly proportional.
4. Avogadro Principle: moles and P or V; directly proportional.
Slide 14 THE GAS LAWS DEMOS Boyles Law Chapter 7 Breathing and
Boyles Law 1. Why does the balloon expand? 2. What does this demo
have to do with breathing? 3. Have you ever heard the phrase nature
abhors a vacuum? What do you think it means? Cartesian Diver World
record dive Balloon and bottle Artificial lung Slide 15 BOYLES LAW
Slide 16 THE LAW: For a given mass of gas, at a constant
temperature, the volume varies inversely with the pressure:P 1 V 1
= P 2 V 2 PRACTICE: The pressure in a 9.0 L balloon is 2.1 atm. If
the volume is reduced to 5.0 L, what will the resulting pressure
be? (Temperature does not change.) V 1 = 9.0 LV 2 = 5.0 L P 1 = 2.1
atmP 2 = ? atm P 1 V 1 = P 2 V 2 P 2 = P 1 V 1 = V 2 Slide 17
REMINDER EVERY TIME you do a gas laws problem: 1. Write what you
know and what you are trying to find 2. Write the formula 3. Plug
in the numbers with units and solve with the correct number of sig
figs. Slide 18 GAS LAWS DEMO Balloon and temperature change Slide
19 CHARLES LAW Slide 20 THE LAW: The volume of a fixed mass of a
gas is directly proportional to its KELVIN temperature if the
pressure is constant. If pressure is kept constant, then volume
must change to keep temperature the same. V 1 = V 2 T 1 T 2 You
must use the Kelvin temperature scale! K = C + 273 PRACTICE: The
temperature of a sample of gas is 300.0 K. The gas volume is 25.0
L. What will be the new volume of the gas if the temperature is
dropped to 125.0 K? V 1 = 25.0 L V 2 = ? LV 2 = T 2 V 1 = T 1 =
300.0 K T 2 = 125.0 K T 1 Slide 21 GAS LAWS Videodisc Chapter 5 -
Imploding Can 1. Why did the can implode? 2. How does the
demonstration you just saw relate to a barometer? 3. How is a
vacuum seal created on a jar of homemade preserves? Egg in a bottle
Bulb with pressure gauge Slide 22 GAY-LUSSACS LAW Slide 23 THE LAW:
An increase in temperature increases the frequency of collisions
between gas particles. In a given volume, raising the KELVIN
temperature also raises the pressure. P 1 = P 2 T 1 T 2 You must
use Kelvin temperature scale! PRACTICE: The temperature of a sample
of gas is 300.0 K. The gas pressure is 1.4 atm. What will be the
new pressure of the gas be if the temperature is dropped to 125.0
K? P 1 = 1.4 atm P 2 = ? atmP 2 = T 2 P 1 = T 1 = 300.0 K T 2 =
125.0 K T 1 Slide 24 REMINDER EVERY TIME you do a gas laws problem:
1. Write what you know and what you are trying to find 2. Write the
formula 3. Plug in the numbers with units and solve with the
correct number of sig figs. Slide 25 DO NOW Pick up handout due
tomorrow Copy problem set info - due Feb. 25 Ch. 12 #1, 2 Ch. 13
#1, 2, 5, 6, 8, 9, 11,16, 21, 26, 27, 36, 38, 39, 42 Paper towel
drive ends Friday, 3:30. Balloons and Cans lab due Feb. 19. Slide
26 HINT PTV Slide 27 PUTTING IT ALL TOGETHER Simulation on gas
laws: Structure and Properties of Matter Slide 28 AVOGADROS
PRINCIPLE Volume: 22.4L 22.4L 22.4L Mass: 39.95g 32.00g 28.02g
Quantity: 1 mol 1 mol 1 mol Pressure: 1 atm 1 atm 1 atm
Temperature: 273K 273K 273K Slide 29 AVOGADROS PRINCIPLE DEMO Beach
Ball Slide 30 AVOGADROSS PRINCIPLE Particles of different gases
vary greatly in sizes. But size is not a factor The Law: equal
volumes of gases at the same temperature and same pressure contain
equal number of particles. In gas law problems moles is designated
by an n. One mole of a gas has a volume of 22.4 L (dm 3 ) at
standard temperature and pressure (STP). It also has 6.02 x 10 23
particles of that gas. Slide 31 DALTONS LAW OF PARTIAL PRESSURES
Slide 32 THE LAW: The sum of the partial pressures of all
components of a gas mixture is equal to the total pressure of the
gas mixture. P total = P 1 + P 2 + P 3 + P 4 +..... PRACTICE (Easy
Type): What is the atmospheric pressure if the partial pressures of
nitrogen, oxygen, and argon are 604.5 mm Hg, 162.8 mm Hg, and 0.500
mm Hg, respectively? P total = P 1 + P 2 + P 3 P total = Slide 33
DALTONS LAW OF PARTIAL PRESSURES (Chapter 12) Slide 34 DALTONS LAW
OF PARTIAL PRESSURES PRACTICE (Hard Type): A quantity of oxygen gas
is collected over water at 8 C in a 0.353 L vessel. The pressure is
84.5 kPa. What volume would the DRY oxygen gas occupy at standard
atmospheric pressure (101.3 kPa) and 8 C. (The dry gas pressure of
water at 8 C is 1.1 kPa) T 1 = 8CT 2 = 8C V 1 = 0.353LV 2 = ? P 1 =
84.5 kPa 1.1 kPa = 83.4 kPaP 2 = 101.3 kPa You must correct the
pressure so that you can have the DRY gas without the water
pressure added in. P 1 V 1 = P 2 V 2 V 2 = P 1 V 1 = P 2 Slide 35
GAS LAWS Videodisc Chapter 9 Scuba Diving 1. Think about your lungs
as a flexible 6-liter container full of a gas at STP. How would
lung volume change at a depth of 30 meters? 2. Why not increase the
oxygen to 100% and go really deep? 3. What are the bends? How do
divers avoid them? Slide 36 COMBINING THE LAWS From the Boyles,
Charles, and Gay-Lussacs laws, we can derive the Combined Gas Law:
P 1 V 1 = P 2 V 2 T 1 T 2 Mnemonic: Potato and Vegetable on top of
the Table Slide 37 COMBINED GAS LAW PRACTICE: The volume of a gas
measured at 75.6 kPa pressure and 60.0C is to be corrected to
correspond to the volume it would occupy at STP. The measured
volume of the gas is 10.0 cm 3. P 1 = 75.6 kPaP 2 = 101.3 kPaP 1 V
1 = P 2 V 2 V 1 = 0.0100 LV 2 = ? T 1 T 2 T 1 = 333.0KT 2 = 273 K V
2 = P 1 V 1 T 2 = ___________________________ T 1 P 2 Slide 38
STANDARDS T = 0C = 273 K V = 22.4 L (at STP) P = 1.00 atm = 101.3
kPa = 760.0 mm Hg = 760.0 torr Remember only kPa has limited
sigfigs. Slide 39 COMBINED GAS LAW PRACTICE: Correct the volume for
a gas at 7.51 m 3 at 5.0C and 59.9 kPa to STP. Slide 40 IDEAL GAS
LAW Ideal Gas Equation: PV = nRT R is the universal gas constant.
Slide 41 UNIVERSAL GAS CONSTANTS R = 0.0821 L atm mol K R = 62.4
Lmm Hg mol K R = 62.4 L torr mol K R = 8.31 L kPa mol K Why are
there four constants? Slide 42 IDEAL GAS LAW Remember: 1. Always
change the temperature to KELVINS and convert volume to LITERS 2.
Check the units of pressure to make sure they are consistent with
the R constant given or convert the pressure to the gas constant
(R) you want to use. Slide 43 IDEAL GAS LAW PRACTICE: How many
moles of a gas at 100.0C does it take to fill a 1.00 L flask to a
pressure of 1.50 atm? V = 1.00 L T = 100.0C = 373.0 K P = 1.50 atmR
= 0.0821 atmL n = ? molK PV = nRT n = PV =
____________________________ = RT Slide 44 IDEAL GAS LAW PRACTICE:
What is the volume occupied by 9.45g of C 2 H 2 at STP? Hint -
convert grams to moles..... 9.45g C 2 H 2 1 mol C 2 H 2 = 0.363 mol
26.04g C 2 H 2 P = 1.00 atmR = 0.0821 atmL V = ? mol K n = 0.363
molT = 273.0K Slide 45 PRACTICE P = 1.00 atmT = 273K V = ?R =
0.0821 L atm N = 0.363mol mol K V = nRT = (0.363mol)(273K)(0.0821 L
atm)= P (1.00 atm) (mol K) = 8.14L Slide 46 GRAHAMS LAW OF EFFUSION
or DIFFUSION (Chapter 12) The rate of diffusion/effusion is
inversely proportional to the square root of its molar mass under
identical conditions of temperature and pressure. If two bodies of
different masses have the same kinetic energy, the lighter body
moves faster. Slide 47 DEMO Anise and Cinnamon 1. What can we
assume about the temperatures of the two oils? 2. How is
temperature related to KE? 3. How doe the KE of the two oils
compare? 4. What is the formula for KE? Slide 48 CALCULATIONS KE =
mv 2 m a v a 2 = m c v c 2 m a v a 2 = v c 2 m c m a = v c 2 m c v
a 2 m a = v c 2 m c v a 2 Slide 49 GRAHAMS LAW OF EFFUSION or
DIFFUSION (Chapter 12) Rate (velocity) a = Formula mass b Rate
(velocity) b Formula mass a Compare ammonia and hydrochloric acid:
velocity NH 3 = 36.45g/mol velocity HCl 17.04g/mol = NH 3 is 1.46
times faster than HCl Slide 50 REAL vs. IDEAL GASES The ideal gas
equation, PV = nRT, is simple to use and accurately predicts gas
behavior in many everyday situations. Under very high pressure,
real gases have trouble compressing completely. The ideal gas law
fails. Ideal gases have no volume, but real gases do. Slide 51 REAL
vs. IDEAL GASES At very low temperatures, attractive forces between
real gas molecules become significant and real gases liquefy. The
ideal gas law can be used under ordinary conditions only. Slide 52
GAS STOICHIOMETRY We are now going to add to our MOLE CITY diagram,
adding volume of a mole of gas. VOLUME 1 mol 22.4 L @ STP 1 mole 1
mole PARTICLES MOLE MASS 6.02 x 10 23 molar mass Slide 53 GAS
STOICHIOMETRY PRACTICE A. Determine the volume in 2.0 moles of H 2.
?? volume = 2.0 mol H 2 22.4 L H 2 = 1 mol H 2 = 45 L H 2 Slide 54
GAS STOICHIOMETRY B. Determine the volume in 10.3 moles of CO 2. ??
volume = Slide 55 GAS STOICHIOMETRY C. Determine the moles in 251 L
of O 2. ?? moles = Slide 56 GAS STOICHIOMETRY D. What volume of
hydrogen gas is needed for the complete reaction between nitrogen
gas and hydrogen gas to produce ammonia? You are given 5.0L of
nitrogen gas. This problem involves not a mass to mass problem but
a volume to volume problem. The balanced equation is N 2 + 3H 2 2NH
3 Slide 57 ? L H 2 5.0L N 2 N 2 + 3H 2 2NH 3 Slide 58 GAS
STOICHIOMETRY E. What volume of oxygen gas is needed for the
complete reaction between oxygen gas and potassium chloride to
produce potassium chlorate? You are given 45.0g KCl. This problem
involves not a volume to volume problem but a mass to volume
problem. The balanced equation is 2KCl + 3O 2 2KClO 3 Slide 59 ?L O
2 45.0g KCl 2KCl + 3O 2 2KClO 3 Slide 60 HOMEWORK Ch. 13 #40-41,
43-44 due tomorrow Grahams Law handout due tomorrow. Quiz is now
Monday March 3. Dry Ice lab will be Friday. Giant Problem set due
March 4. Test is March 5. Slide 61 Get out Gas Diffusion lab
ANALYSIS and CONCLUSION: 1. Calculate the ratio of the distance
moved. Since both gases moved through the glass tube in the same
amount of time, the distances the gases moved can be used as a
measure of the rates of diffusion of the gases. Substituting the
distance (d) each gas moved for the velocity of the gas. Determine
the ratio of the distance moved. Show your work. This is the
experimental ratio. USE THE CLASS AVERAGE FOR THIS. d 1 = m 2 HCl =
distance NH 3 traveled d 2 m 1 NH 3 distance HCl traveled Slide 62
ANALYSIS and CONCLUSION 2. Determine the true rate of diffusion for
ammonia (m 1 )to hydrochloric acid (m 2 ). Use the masses from the
periodic table. Write the formula and show your work. 3. How close
is your experimental value to the molecular mass ratio? Calculate
your percent error. Write the formula and show your work. Slide 63
GAS LAW PROBLEMS DIRECTIONS Be sure to write: What you know and
where you are going (V 1, V 2, P 1, P 2, T 1, T 2, etc.) The
formula Rewrite the formula to solve for the unknown and fill in
the known data. Show all units. Write the correct answer with
sigfigs and units. Slide 64 GAS LAW PROBLEMS DIRECTIONS For
stoichiometry: write what you know and where you are going Write
the balanced equation if not given. Convert to moles, do the mole
ratio, and convert to what is asked for. Slide 65 Gas Law Problems
#1 1. A sample of oxygen gas occupies a volume of 250.0 mL at 740.0
torr pressure. What volume will it occupy at 800.0 torr pressure?
Slide 66 Gas Laws #1 Answer V 1 = 250.0mL V 2 = ? P 1 = 740.0 torrP
2 = 800.0 torr Boyles Law V 2 = V 1 P 1 = (250.0mL)(740.0torr) = P
2 (800.0torr) = 231.25 = 231.3 mL Slide 67 DETERMINING MOLAR MASS
We can use the ideal gas equation to calculate the molar mass of a
gas from laboratory measurements. The molar mass formula is Molar
mass, MM = mass, m/moles, n So, n (moles) is equal to: moles, n =
mass, m Molar mass, MM Slide 68 DETERMINING MOLAR MASS So, if n =
m/M, substitute it in the formula. The ideal gas equation can be
written as PV = mRT MM = mRT MMor P V Slide 69 PRACTICE What is the
molar mass of a gas if 100.0 dm 3 has a mass of 7.202g at 110C and
107.0 kPa? MM =T = V =P = m =R = MM = mRT = P V Slide 70
DETERMINING DENSITY This modified version of the ideal gas equation
can also be used to solve for the density of a gas. PV = nRT bcomes
D = PMM RT Slide 71 DETERMINING DENSITY MM = mRT P V rewrite with
m/V on one side PMM = m RT V D = m = PMMor D = PMM V RT RT Slide 72
PRACTICE Find the density of NH 3 in g/L at 752 mm Hg and 55C. MM =
T = R = P = D = PMM = RT Slide 73 PRACTICE 1. Calculate the molar
mass, MM, of a gas if 150.0 dm 3 has a mass of 75.0 g at 100C and
95 kPa. Slide 74 PRACTICE 1. Calculate the molar mass, M, of a gas
if 150.0 dm 3 has a mass of 75.0 g at 100C and 95 kPa. MM =?T =
373K V =150.0LP = 95kPa m =75.0gR = 8.31 L kpa mol K MM = mRT =
(75.0g)(373K)(8.31L kpa) P V (95kPa)(150.0L)(mol K) = 16.31384 =
16g/mol Slide 75 PRACTICE 2. Determine the density of chloroform
gas, CHCl 3 if a sample massing is collected in a flask with at 37C
and a pressure of 728 mm Hg. Slide 76 PRACTICE MM = 119.37g/molT =
310K R = 62.4 L mmHgP = 728mmHg mol K D = PMM =
(728mmHg)(119.37g)(mol K) RT (310K)(62.4 L mmHg)(mol) = 4.492419 =
4.5g/L Slide 77 GAS LAWS QUIZ MONDAY There will be six problems.
Could be any from this list: Boyles/ Charles / Gay-Lussac Daltons
Law of Partial Pressure Combined Gas Law Ideal Gas Law Grahams Law
of Diffusion Gas Stoichiometry Extra Credit is Density or Molar
Mass problem
