chemistry 30s & honours gases & the atmosphere prezi...

Chemistry 30S & Honours Gases & The Atmosphere Prezi Presentation

Assignment Description You and a partner will generate and present an attractive and informative presentation based on a topic of your choice having to do with gases and the atmosphere. Your dynamic presentation should involve the other members of the class and will be no longer than 5 minutes. The following information must be contained in a minimum of five slides as part of a Prezi from www.prezi.com :

A clear and concise description of your selected topic worded using language that all of your classmates may understand

A creative and eye catching presentation that includes a minimum of 3 ways of presenting information (text, pictures, diagrams, sound, graphs, videos/animations) in a stylish format

An explanation of how your topic relates to at least one of the Gas Laws (Boyle’s, Charles’, Gay-Lussac’s, and the combined Gas Laws)

A specific explanation of particle behaviour according to the Kinetic Molecular Theory of Gases as it relates to your topic

A concise handout summarizing the content of your presentation using two different ways to communicate the

information A complete references cited list of all resources used with active hyperlinks, including references to photographs,

sounds and videos, presented as a separate slide at the end of the presentation

Some suggestions for involving members of the class: o demonstration o very short game o quiz

Remember that whatever method you choose to engage members of the audience counts as part of your 5 minute presentation time.

Topic List Research may be done on any of the following topics. No two groups may research the same topic. All students must write their names on a sign up sheet and have their topic approved by the instructor BEFORE researching a topic.

SCUBA diving Hot air balloons Air intake systems

The role of gases in volcanoes Methods of collecting and storing

gases

High altitude training

Airbags Carbonated beverages How helicopters use gases Lake overturn Blimps (airships) How hovercrafts use gases

Things that use propane gas Weather balloons vs High altitude

balloons Role of gases in breathing

Hyperbaric chambers How submarines use gases Airplane pressure Formation of the atmosphere of

a planet of your choice

Gases in products or packaging

(for example, the Aero bar)

Pneumatic devices

Projectiles that use gases Gas propellants in cans Topic approved by

instructor

Timeline

Research Day1

Research Day2 Presentation Day1 Research Day3 Presentation Day2

http://www.prezi.com/


Student 1:

Student 2:

Prezi Rubric

Criteria Emerging (0-1) Developing (2) Proficient (3)

Information is

understandable

Information is too wordy and uses terms that most students do

not understand

Only one of the required criteria is met

Information is concise and worded using language that all

students may understand

Document contains

relevant information

Explanations pertaining to the Gas

Laws and particle behavior according to KMT as it relates to

your topic are missing or contain significant

errors

Only one of the required criteria is met

or contains minor errors

Document includes explanations of how

the topic relates to one or more of the Gas

Laws & particle behavior according to KMT as it relates to

your topic

Document uses multiple

ways to represent

information

Information contained in poster is presented

in only one way (1)

Two ways of presenting information

are present

Minimum of 3 ways of presenting information

are present (text, colour, pictures,

diagrams, sound, graphs,

videos/animations)

References cited page

References used are not submitted with the

document (0)

An incomplete list of references used is

part of the document or is submitted in another format

All references used, including videos and graphics, are cited with active hyperlinks on a separate slide at the end of the presentation

/12


Student 1:

Student 2:

Presentation Rubric

Criteria Novice (1) Intermediate (2) Expert (3)

Presentation is dynamic

Group does not incorporate the members of the

audience and the presentation is not

smooth

Only one criteria met

Presentation is practiced and engages

members of the audience.

Students stick to the

five minute time

limitation

Video(s) is/are most of the presentation or the presentation is longer

than 7 minutes

Only two criteria met

Presentation is not rushed or too slow, is between 4.5 and 5.5 minutes, and videos

are no longer than 30 seconds

Each group member

participates in an

equitable way

One partner conducts the entire presentation

Evidence that one student presented

more than the other

All group members share the role of

presenting equitably

Summary Handout

Information in handout does not match with

the content of the presentation or no

handout is presented

New information is presented in handout

that is not contained in the presentation or

relevant information is missing or handout

only uses one way of conveying information

Handout uses minimum of 2 different ways to communicate information and is a concise summary of

all of the main aspects of the presentation

Presentation Time: __________min. __________sec. Video1 Start Time: Video1 Stop Time:

Video2 Start Time: Video2 Stop Time:

/12

/24

A COOL CANTwo companies developing theself-chilling can have overcomethe obstacles. They haveperfected a way to Inject thegas quickly and to vent it slowly

so the gas does not simply chillthe air outside the can.

The can works on theprinciple that when acompressed gas expands, Itstemperature falls. Inside eachcan Is a metal capsule filledwith carbon dioxide under highpressure. A valve releases thegas, cooling the outside of thecapsule and thus the beverage.In volume production theprocess could add 2 to 5 centsto the 8-cent cost of making aconventional can. The carbondioxide chills a beverage byabout 15°C. within a minute anda half. Both companies say theywill market the process instandard 280 mL cans.Consumers will pay more forless beverage because thecapsule takes up 40 -50 mL ofspace.

F.2 Fr

^^

theaptIde

Gases tend tm1. fill the entire

expand upon.,v

3. be casib,

The Ideal Gast

This model for gasesIt

T%a*.* o(Gasets. It is based on fourpostulates. Each postul is

observed fads:^Yt

EostulsttdlThe tiny molecules

so far apart from each other that

the actual volume ^tita nr irltpnii^pi#^tauat when compared to the space be-

Fact: Under normal coat

Yot tt 11 Op etetI - R and pressure about 99.96% of

t

la

space. Gases, therefore, canthe total volume,be easily sxxni

Postulateetwem moecules in a perfect (ideal) gas.No intermolecular form exist

Fact: Gases freely and spPfously I the entire space available to them.Under conditions od A pressure and low temperature, however,intermolecular forces lend to be significant. Nevertheless, the fact

is still observed

Postulate 3Molecules of a gas are constantly moving in rapid, straight-line motion. They col-

lide constantly with each

the sides of the container. Energy is ex-

changed in these collisions bait no energy is lost. The collisions are said to becompletely elastic.

Fact: A Brownian motion appav*= can be used to show that gas molecules arein continuous motion. Particles of dust or smoke are added to thegas (air) in the apparatus. Even though the gas molecules are toosmall to be seen, the particles of smoke can be observed through amicroscope. These particles move continuously as if they werebeing hit by the invisible gas molecules. Since the dust particlesdo not settle art, we can assume that these collisions are strongenough to overcome the pull of gravity on the dust particles.

Postulate 4At any given time, not all molecules of the gas have the same speed and, therefore,their individual kinetic energies also vary. However, on the average the kineticenergies of different gasses are the same and the average kinetic energy of themolecules varies directly (i.e. the average kinetic energy of the gas molecules in-creases as temperature increases) with the absolute temperature of the gas.

Fact: Collisions between molecules of gas will continually cause their speed tochange. However, the collisions are elastic and thus, no kinetic ener-gy is lost during these collisions. The total kinetic energy of the sys-

tem is the sum of the kinetic energies of all the molecules. If thetemperature of the gas is increased by adding beet, the averagekinetic energy of the particles will in=ease proportionately.

KMT Questions

Use the particle theory of matter to answer thefollowing questions:

1. Why is it easier to compress a gas than a liquid?

2. What causes pressure? Use your answer toexplain how air inside a balloon stretches therubber out.

3. The air pressure inside an automobile tireincreases when the tire becomes warm. Why isthis so?

4. Why must heat be removed to change liquidwater to ice?

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15:3 MEASURING PRESSURE

In measuring gas pressure, an instrument called a manometer (mah

vAH,'w uh tuhr) is used. Two types of manometers are shown in Figure

15-3. In the "open" type, air exerts pressure on the column of liquid in

one arm of the U-tube. The gas being studied exerts pressure on the other

arm. The difference in liquid level between the two arms is a measure of

the gas pressure relative to the air pressure. If you know the density of the

liquid in the manometer, you can calculate the pressure difference

between the gas and the air.

p,, = 105 mm = 14.0 kPa

Valve closed

C-AK'

1110

101.3 kPa

- 87.3 kPa

14.0 kPa = Pressure

of the gas

The "closed" type of manometer has a vacuum above the liquid in

one arm. The operation of a closed-arm manometer is independent of air

pressure. A closed-arm manometer used to measure atmospheric pressure

is called a barometer. Most barometers are manufactured with a scale

calibrated to read the height of a column of mercury in millimetres. Aver-

age air pressure will support a column of mercury 760 mm high. Since

average air pressure is defined as 101.325 kPa, then 101.325 kPa = 760

easuring Pressure

287

FIGURE 15-3. Closed (a) andopen arm (b) manometers areused to measure gas pressure.

FIGURE 15-4. This barometer (a)is used to measure air pressurein the laboratory. This gauge (b)measures air pressure in tires.A sphygmomanometer (c) isused to measure blood pres -

sure.

655 mm

105 mm

Hg ---(

a

288

Kir?etic Theory

mm. By dividing both sides of the equation by 101.325 we find that 1 kPa= 7.50 mm Hg.

Closed-arm manometers can be used to measure actual or "abso.lute" gas pressure. It is also possible to calculate the absolute pressure of a

gas using an open manometer. However, a barometer must be available

to measure the atmospheric pressure on the outside arm of the openmanometer. The following examples show some typical calculationsinvolving gas pressure.

EXAMPLE: PressureThe open manometer in Figure 15-3 is filled with mercury. The difference

between mercury levels in the two arms is 6 mm. What is the total pres....sure, in kilopascals, of the gas in the container? The air pressure is 101.3kPa.

Solving Process:

The mercury is higher in the arm connected to the gas. Thus, the pressureexerted by the gas must be less than that of the air. As a result, we mustsubtract the pressure of the mercury from the air pressure to get the gaspressure. Before subtracting, however, we must convert the 6 mm differ -ence in height to kilopascals.

1 kPa =

.50 mm - 0.8 kPa7

Now we can subtract the two pressures.

101.3 - 0.8 = 100.5 kPa

EXAMPLE.- PressureSuppose the difference in height of the two mercury levels in the closedmanometer in Figure 15-3 is 238 mm. What is the pressure in kilopascalsof the gas in the container?Solving Process:Since the column of mercury is 238 mm high and 7.50 mm of mercuryequals 1 kPa, the pressure is

238 man-

1 kPa

1. An open manometer, such as the one in Figure 15-3, is filled withmercury and connected to a container of hydrogen. The mercurylevel is 62 mm higher in the arm of the tube connected to the gas

Air pressure is 97kilopascals?A closed manomeand connected toof mercury in thenitrogen in kilopaAn open manometainer of oxygen.the tube connecte,kPa. What is the i

4. An open manomet38 mm higher in96.3 kPa, what is

5. A closed manometainer of helium.

two arms is 86.0helium?

15:4 KINETICThe average speei

temperature and the mitide mass related?

Kinetic energy ismotion. Temperature i -kinetic energy of molecia particular temperatur

temperature, the averagkinetic energy of a partivelocity. Therefore, at a

v constant

K.E.

6 n rr

7.50 man-31.7kPa

2.

3.

or "abso-essure of a

availablethe open

ilculations

I that 1 kPa

15:4 Kinetic Energy and Temperature 289

differencetotal pres-e is 101.3

pressurewe must

et the gasim differ-

mercury

Air pressure is 97.7 kPa. What is the pressure of the hydrogen in

kilopascals?

2. A closed manometer like the one in Figure 15-3 is filled with mercury

and connected to a container of nitrogen. The difference in the height

of mercury in the two arms is 691 mm. What is the pressure of the

nitrogen in kilopascals?

3. An open manometer is filled with mercury and connected to a con-

tainer of oxygen. The level of mercury is 6 mm higher in the arm of

the tube connected to the container of oxygen. Air pressure is 100.0

kPa. What is the pressure, in kilopascals, of the oxygen?

4. An open manometer connected to a tank of argon has a mercury level

38 mm higher in the atmospheric arm. If atmospheric pressure is

96.3 kPa, what is the pressure of the argon?

5. A closed manometer is filled with mercury and connected to a con-

tainer of helium. The difference in the height of mercury in the

two arms is 86.0 mm. What is the pressure, in kilopascals, of the

helium?

15:4 KINETIC ENERGY AND TEMPERATURE

The average speed of the particles in a gas depends only on the

temperature and the mass of the particles. How are temperature and par-

ticle mass related?

Kinetic energy is the energy an object possesses because of its

motion. Temperature is a measure of that kinetic energy. The average

kinetic energy of molecules or atoms in a gas is the same for all particles at

a particular temperature. In other words, if two gases are at the same

temperature, the average kinetic energies of their particles are equal. The

kinetic energy of a particle is equal to mv2/2, where m is its mass and v its

velocity. Therefore, at a given temperature, a particle with small mass will

FIGURE 15-5. The cotton on oneend of the tube is saturated withconcentrated HCL The cotton atthe other end Is saturated withNH3(aq). The formation ofNH4CI is shown by the whitering in the tube. By noting theposition of the ring, can you de-termine which end of the tubecontains HCI?

ed withmercuryhe gas.

v0

v constant m constant

K.E.

K.E.

FIGURE 15-6. The first twographs show the relationshipsamong mass, velocity, and ki-netic energy. The third graphshows that in any given samplesome particles will have moreor less energy than the averageparticle.

w

290

Kinetic Theory

-273'C or

FIGURE 15-7. Theoretically, thepoint at which molecular mo-tion ceases (KE = O) is absolutezero (-273°C).

Cold

FIGURE 15-8. Heat flows fromhot objects to cooler onesthrough a transfer of kinetic en-ergy when particles collide.

move faster than a particle with large mass. A decrease in the temperature

of a substance means the particles of the substance are moving more

slowly. An increase in temperature means the particles are moving

faster.In theory, it should be possible to lower the temperature to a point

where all molecular motion ceases. The temperature at which all molec-

ular motion should cease is known as absolute zero. It is -273.15°C. Thisvalue is usually rounded to -273°C.

To make a temperature scale based on absolute zero, scientists have

agreed on a system known as the absolute, or kelvin scale. The zero point

of the kelvin scale is absolute zero. The divisions, or degrees, are the

same size as those of the Celsius scale. Therefore,

K=°C+273

The kelvin is the SI unit of temperature.

Temperature can be used to determine the direction of flow of

energy. Energy always flows from a warmer object to a cooler one. Ki-

netic theory explains the flow of energy in terms of particle collisions. The

particles of the warmer object and the cooler object have unequal kinetic

energy. The excess kinetic energy of the particles in the warmer object is

passed on to the particles of the cooler object as they collide, Figure 15-8.

The particles of the cooler object gradually receive more kinetic energy

until the average kinetic energy of both objects is the same. For example,

you can feel the air warm near a bowl of hot soup. If left undisturbed the

soup and bowl will eventually reach room temperature. Heat is the

amount of energy transferred. Heat, like energy, is measured in joules.

6. Convert the folio'

a. 65°

b. 1 f

7. Convert the folio,

a. 86

b. 1 `

8. Convert the folio'

a. 23°

b. 51

9. Convert the folio,

a. 872

b. 61

10. At 25°C, which c

a. N2

b. F:

15:5 STATES 'Matter exists in fc

our discussion of the

kinetic theory can alliquids. Plasmas are t

Gas particles are

line. Change of direcanother, or when a pi

particles, then, traveluntil they collide witgases assume the sha

The particles of zmotion. Actually, the?with near neighbors. -often shifts as one piamount of space bet,relative positions contvolume, assume the

In solids, a partic

the surrounding partic

fixed point. Again, tlbetween collisions wioxygen gas at 25°C tri

diameter before collieparticles are closely pof their diameters beftides arranged in a deshape and, a definite

The physical statatmospheric pressure

re

re

Ig 6. Convert the following temperatures from Celsius to kelvin,

a. 65°

b. 16°

c. 48°

d. - 36°

e.

7. Convert the following temperatures from kelvin to Celsius.

a. 86

b. 191

c. 533

d. 321

e. 894

8. Convert the following temperatures from Celsius to kelvin.

a. 23°

b. 58°

c. -90°

d. 18°

e. 25°

9. Convert the following'femperatures from kelvin to Celsius.

a. 872

b. 690

c. 384

d. 20

e. 60

10. At 25°C, which of the following gas molecules move fastest?

a. N2

b. F2

C. CO

d. 02

15:5 STATES OF MATTER

Matter exists in four states-solid, liquid, gas, and plasma. Thus far,

our discussion of the kinetic theory has been limited to gases. However,

kinetic theory can also be used to explain the behavior of solids and

liquids. Plasmas are treated as a special case.

Gas particles are independent of each other and move in a straight

line. Change of direction occurs only when one particle collides with

another, or when a particle collides with the walls of the container. Gas

particles, then, travel in a completely random manner. Since they travel

until they collide with a neighbor or with the walls of their container,

gases assume the shape and volume of their container.

The particles of a liquid have what appears to be a vibratory type of

motion. Actually, they are traveling a straight-line path between collisions

with near neighbors. The point about which the seeming vibration occurs

often shifts as one particle slips past another. These differences in the

amount of space between particles allow the particles to change their

relative positions continually. Thus, liquids, although they have a definite

volume, assume the shape of their container.

In solids, a particle occupies a relatively fixed position in relation to

the surrounding particles. A particle of a solid appears to vibrate about a

fixed point. Again, the particle is actually traveling a straight- line path

between collisions with very near neighbors. For example, a molecule of

oxygen gas at 25°C travels an average distance equal to 314 times its own

diameter before colliding with another molecule. In a solid, however, the

particles are closely packed and travel a distance equal to only a fraction

of their diameters before colliding. Unlike liquids, solids have their par-

ticles arranged in a definite pattern. Solids, therefore, have both a definite

shape and, a definite volume.

The physical state of a substance at room temperature and standard

atmospheric pressure depends mostly on the bonding in the substance.

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Boyles' Law

Use Boyles' Law to answer the following questions:

1) 1.00 L of a gas at standard temperature and pressure is compressed to473 mL. What is the new pressure of the gas?

2) In a thermonuclear device, the pressure of 0.050 liters of gas within thebomb casing reaches 4.0 x 106 atm. When the bomb casing is destroyedby the explosion, the gas is released into the atmosphere where itreaches a pressure of 1.00 atm. What is the volume of the gas after theexplosion?

3) Synthetic diamonds can be manufactured at pressures of 6.00 x 104 atm.If we took 2.00 liters of gas at 1.00 atm and compressed it to a pressureof 6.00 x 104 atm, what would the volume of that gas be?

4) The highest pressure ever produced in a laboratory setting was about 2.0x 106 atm. If we have a 1.0 x 10-5 liter sample of a gas at that pressure,then release the pressure until it is equal to 0.275 atm, what would thenew volume of that gas be?

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Atmospheric pressure on the peak of Mt. Everest can be as low as 150mm Hg, which is why climbers need to bring oxygen tanks for the last partof the climb. If the climbers carry 10.0 liter tanks with an internal gaspressure of 3.04 x 104 mm Hg, what will be the volume of the gas when itis released from the tanks?

6)Part of the reason that conventional explosives cause so much damage isthat their detonation produces a strong shock wave that can knock thingsdown. While using explosives to knock down a building, the shock wavecan be so strong that 12 liters of gas will reach a pressure of 3.8 x 104 mmHg. When the shock wave passes and the gas returns to a pressure of760 mm Hg, what will the volume of that gas be?

7)Submarines need to be extremely strong to withstand the extremely highpressure of water pushing down on them. An experimental researchsubmarine with a volume of 15,000 liters has an internal pressure of 1.2atm. if the pressure of the ocean breaks the submarine forming a bubblewith a pressure of 250 atm pushing on it, how big will that bubble be?

8) Divers get "the bends" if they come up too fast because gas in their bloodexpands, forming bubbles in their blood. If a diver has 0.05 L of gas in hisblood under a pressure of 250 atm, then rises instantaneously to a depthwhere his blood has a pressure of 50.0 atm, what will the volume of gas inhis blood be? Do you think this will harm the diver?

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Charles' Law Activity

Objective1. Develop the relationship between volume and temperature at constant pressure.2. Calculate absolute zero using experimental data.

Procedure and Calculations1. Given the following data, graph volume in millilitres on the y-axis versus

temperature on the x-axis. Set up your graph so that the domain (x-axis) spansfrom - 300°C to 100°C and the range (y-axis) spans from 0 mL to 300 mL. Donot use squiggly lines!

Temperature (°C) 91.9 75 50 20 - 1.8 - 10u .e

Volume (mL)

267 256 238 217 202 196 193

-15

2. Use a ruler to sketch the line of best fit, extrapolating the line to where itintersects the x-axis.

3. On your graph, calculate the slope of the graph and determine the value of the y-intercept.

4. Determine the actual value of the x-intercept.

5. Use the formula VI/TI = V2/T2 for any two data points. What do you observe?

6. Use the same formula again for the same two data points, only this time add thevalue of the x - intercept to the temperature. What do you observe?

Conclusion1. State the relationship between volume and temperature at constant pressure.

2. What is the value of absolute zero according to the experimental data? What isthe actual value of absolute zero? Why does the experimental value differ fromtrue value?

Date:

Assignment:

From:

To: Page No.:

Form 4A-BW. Q 2000 Mathematics Help Central

http://www.mathematicshelpcentrat.com

Charles' Law Worksheet

1) The temperature inside my refrigerator is about 4° Celsius. If I place aballoon in my fridge that initially has a temperature of 22° C and a volumeof 0.5 liters, what will be the volume of the balloon when it is fully cooledby my refrigerator?

2) A man heats a balloon in the oven. If the balloon initially has a volume of0.4 liters and a temperature of 20 °C, what will the volume of the balloonbe after he heats it to a temperature of 250 °C?

3) On hot days, you may have noticed that potato chip bags seem to"inflate", even though they have not been opened. If I have a 250 mL bagat a temperature of 19 °C, and I leave it in my car which has atemperature of 60° C, what will the new volume of the bag be?

4) A soda bottle is flexible enough that the volume of the bottle can changeeven without opening it. If you have an empty soda bottle (volume of 2 L)at room temperature (25 °C), what will the new volume be if you put it inyour freezer (-4 °C)?

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5) Some students believe that teachers are full of hot air. If I inhale 2.2 litersof gas at a temperature of 180 C and it heats to a temperature of 380 C inmy lungs, what is the new volume of the gas?

6) How hot will a 2.3 L balloon have to get to expand to a volume of 400 L?Assume that the initial temperature of the balloon is 25 °C.

7) I have made a thermometer which measures temperature by thecompressing and expanding of gas in a piston. I have measured that at100 C the volume of the piston is 20 L. What is the temperature outsideif the piston has a volume of 15 L? What would be appropriate clothingfor the weather?

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Chemistry 30S- Gay-Lussac Questions

Name:

1) Determine the pressure change when a constant volume of gas at 1.00 atm is heatedfrom 20.0 °C to 30.0 °C.

2) A gas has a pressure of 0.370 atm at 50 .0 °C. What is the pressure at standardtemperature?

3) A gas has a pressure of 699.0 mm Hg at 40 .0 °C. What is the temperature at standardpressure?

4) If a gas is cooled from 323.0 K to 273.15 K and the volume is kept constant what finalpressure would result if the original pressure was 750.0 mm Hg?

5) If a gas in a closed container is pressurized from 15.0 atmospheres to 16.0atmospheres and its original temperature was 25.0 °C, what would the final temperatureof the gas be?

6) A 30.0 L sample of nitrogen inside a rigid, metal container at 20.0 °C is placed insidean oven whose temperature is 50.0 °C. The pressure inside the container at 20.0 °C wasat 3.00 atm. What is the pressure of the nitrogen after its temperature is increased?

7) A sample of gas at 3 .00 x 103 mm Hg inside a steel tank is cooled from 500.0 °C to0.00 °C. What is the final pressure of the gas in the steel tank?

8) The temperature of a sample of gas in a steel container at 30.0 kPa is increased from-100.0 °C to 1.00 x 103 °C. What is the final pressure inside the tank?

9) Calculate the final pressure inside a scuba tank after it cools from 1.00 x 103 °C to25.0 °C. The initial pressure in the tank is 130.0 atm.

Combined Gas Law Problems

Use the combined gas law to solve the following problems.-

1 )

If I initially have a gas at a pressure of 12 atm, a volume of 23 liters, and atemperature of 200 K, and then I raise the pressure to 14 atm andincrease the temperature to 300 K, what is the new volume of the gas?

2) A gas takes up a volume of 17 liters, has a pressure of 2.3 atm, and atemperature of 299 K. If I raise the temperature to 350 K and lower thepressure to 1.5 atm, what is the new volume of the gas?

3) A gas that has a volume of 28 liters, a temperature of 45 °C, and anunknown pressure has its volume increased to 34 liters and itstemperature decreased to 35 °C. If I measure the pressure after thechange to be 2.0 atm, what was the original pressure of the gas?

4) A gas has a temperature of 14 °C, and a volume of 4.5 liters. If thetemperature is raised to 29 °C and the pressure is not changed, what isthe new volume of the gas?

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5) If I have 17 liters of gas at a temperature of 67 °C and a pressure of 88.89atm, what will be the pressure of the gas if I raise the temperature to 94°C and decrease the volume to 12 liters?

6) I have an unknown volume of gas at a pressure of 0.5 atm and atemperature of 325 K. If I raise the pressure to 1.2 atm, decrease thetemperature to 320 K, and measure the final volume to be 48 liters, whatwas the initial volume of the gas?

7) If I have 21 liters of gas held at a pressure of 78 atm and a temperature of900 K, what will be the volume of the gas if I decrease the pressure to 45atm and decrease the temperature to 750 K?

8) If I have 2.9 L of gas at a pressure of 5 atm and a temperature of 50 °C,what will be the temperature of the gas if I decrease the volume of the gasto 2.4 L and decrease the pressure to 3 atm?

9) I have an unknown volume of gas held at a temperature of 115 K in acontainer with a pressure of 60 atm. If by increasing the temperature to225 K and decreasing the pressure to 30 atm causes the volume of thegas to be 29 liters, how many liters of gas did I start with?

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GRADE 11 CHEM ISTRY • Topic 3 Appendices

Appendix 3.9: Determining the Molar Mass of a Gas (Student Experiment)

Purpose

The molar mass of a compound is an important constant that, in some cases, canhelp identify a substance. In this lab, you will calculate the molar mass of butaneusing calculations involving the combined gas lay and the constant 22.4 L/mole.

Materials

• goggles• butane lighter (with flint removed)• plastic bucket• water

• graduated cylinder (1000 mL)• funnel• balance• thermometer• barometer

Procedure

1. Determine the initial mass of the butane lighter.

2. Pour water into the bucket until it is about three-quarters full. Then fill thegraduated cylinder with water and invert it into the bucket so that the waterlevel is within the calibrated region. Record the volume reading.

3. Place the funnel in the mouth of the graduated cylinder while it is under thewater to ensure all butane gas bubbles are collected.

4. Hold the butane lighter in the water under the graduated cylinder and funnelapparatus. Release the butane gas from the lighter into the mouth of thegraduated cylinder until you have displaced from half to three-quarters of thewater within the cylinder.

5. Equalize the pressures inside and outside the cylinder by adjusting the positionof the cylinder until the water levels inside and outside the cylinder are the same.

6. Read the measurement on the cylinder and record the volume of gas collected.

7. Record the ambient (room) temperature and pressure.

8. Thoroughly dry the butane lighter and determine its final mass.

Topic 3 Appendices - 31

GRADE 11 CHEMISTRY • Topic 3 Appendices

Appendix 3.9: Determining the Molar Mass of a Gas (Student Experiment) (continued)

Observations

Data Chart

Initial mass of lighter

Final mass of lighter

Mass of gas released

Initial volume reading on graduated cylinder

Final volume reading on graduated cylinder

Volume of gas released

Room temperature

Room air pressure

Calculations

1. Using the combined gas law, convert the volume of gas released in the lab to thevolume it would occupy at standard temperature and pressure (STP).

2. Use the volume of gas at STP (recorded above) and the gas constant of22.4 L/mole to determine the number of moles of gas collected at STP.

3. Use the mass of gas released (from the data chart) and divide it by the moles ofgas at STP to find the molar mass of the gas.

Conclusions

I. What is the molar mass of the butane according to your lab results?

2. What is the known molar mass of butane according to the periodic table?

3. What is your experimental percent error?

4. Every experiment has some experimental error or uncertainties. State somepossible flaws, limitations, experimental errors, or uncertainties that may affectthe accuracy of your results. Make a list and rank them from most to leastsignificant.

5. It is always possible to omit a source of experimental error. In the experiment,you may not have realized that butane in a lighter is not pure butane butcontains a small quantity of water vapour. For a typical room temperature, thiswould correspond to about 2.6 kPa of the pressure you recorded. Subtract thisvalue from the pressure you used, and use the new pressure to recalculate themolar mass and the experimental percent error. Is your answer significantlymore accurate? Explain.

32 - Topic 3 Appendices


Appendix 3.9: Determining the Molar Mass of a Gas (Teacher Notes

Safety Precautions

• Butane is highly flammable.

• Do not conduct this experiment near an open flame.

• Good ventilation in the laboratory is essential.

• Eye protection is required.

• Flints must be removed from the butane lighters. You can pry off the metalcasing (hood) and the spark wheel of the typical disposable commercial lighterwithout much effort, and the flint and a long spring will just pop out.

Important Notes

• You will need one butane lighter per group.

• An ice cream pail (4 L) works fine for this experiment, but because it is small it isa. little clumsy to use. The funnel could be removed so that you have more handroom, but then students have to be more careful not to lose the bubbles. A sinkfilled with water works well also.

• If you don't have a barometer, you can find the air pressure for your town or cityon a weather website on the Internet.

• After thoroughly drying the lighter, you may also want to let it air dry for awhile so that the interior parts can dry as well. A more accurate mass can berecorded after this is done.

Observations

Sample Data Chart

Initial mass of lighter 18.17 g

Final mass of lighter 18.01 g

Mass of gas released 0.16 g

Initial volume reading on graduated cylinder 21.0 mL

Final volume reading on graduated cylinder 89.8 mL

Volume of gas released 68.8 mL

Room temperature 22°C = 295 K

Room air pressure 102.14 kPa


2


Appendix 3.10: Gas Density Table (Student Resource Material)

Density of Gases at 25°C and 101.3 kPa (760 mmHg or 1.0 atm) Pressure

Name

Ammonia

Argon

Butane

Carbon dioxide

Carbon monoxide

Dichlorine

Ethane

Ethene

Ethyne (acetylene)

Helium

Dihydrogen

Hydrogen chloride

Hydrogen iodide

Krypton

Methane

Neon

Nitrogen monoxide

Dinitrogen

Dinitrogen monoxide

Nitrogen dioxide

Dioxygen

Ozone

Propane

Sulphur dioxide

Xenon

Formula

Molar Mass

(glmol)

NH3

17.03

Ar

39.944

C4Hjo

58.12

CO2

44.01

CO

28.01

Cl2

70.91

C2H6

30.07

C2H4

28.05

C2H2

26.04

He

4.003

H2

2.016

HCl

36.47

HI

127.93

Kr

83.70

CH4

16.04

Ne

20.18

NO

30.01

N2

28.02

N2O

44.02

NO2

46.01

02

32.00

03

48.00

C3H8

44.09

SO2

64.07

Xe

131.30

Density (g/L)

0.696

1.633

2.376

1.799

1.145

2.898

1.229

1.147

1.064

0.164

0.082

1.490

5.228

3.425

0.656

0.825

1.226

1.145

1.799

1.880

1.308

1.962

1.802

2.618

5.367


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