- • .iiÿÿ ÿ =<- :

oUnit s LawsName: ÿ

February 8Stoichiometry TestReview

9StoichiometryTest

22Ideal Gas Law

HW: p.20Study Guide- pgs.24-28

HW: p,8

15Combined GasLawSoda can activity

16

Boyle's, Charles',.ÿ

and Avogadro'sLaw-

HW: pp.14-15

23Stoichiometrywith Gas Laws

HW: p,23 andstudy guide(pp.24-28)

Computer Lab-

24Review for Test

Study Guide DueTODAY!!

10Review forCumulative Retest

17them Think GasLaws Tutorial-

11CumulativeRe-Test

18Gas LawsLab/Activity

Begin working onStudy Guide- pgs.24-28Study for Quiz on,Friday• <

25Gas LawsTest

12Pressure & KineticTheory' of Gases

HW: p.4Bring an emlÿtysoda can to classmonday

QuizDalton's Law ofPartial Pressures

HW: Pg, 17Study Guide- pgs.24-28

26

Class Period:ÿ Test Date:

29. Wÿemass of rbon monoxide gas ifÿ is kept at 0.45arm and 440K?

Name of Gas Law used here:ÿlÿa ÿ-d ÿ1% /03-O ÿ rYlO!ÿo-,In,ÿ CmÿrSioÿ

30, A cylinder with a movable piston contains o.5o!Srÿolÿs of helium at room temperature. More helium wasadded to the cylinder and the votume was adjusted so that the gas pressure remained the same, Hÿmoles of helium were added to the cylinder if the volume was changed from 2.00 L to 2.70 L? ÿ€-ÿSt.ÿ'ÿ..

n,_ÿ,ÿÿ ÿ,- ÿ ÿ ÿ:ÿ--Eÿ'ÿ

I-ÿ, ÿ...--ÿ----

Name of Gas Law used here: 'ÿ"4 0,ÿ O,-a '

31. How many graÿs must decompose in order t6produce_3.113 liters of Clÿ at 50.0°._.__ÿC and

98.4 kPa? 2AIClÿ -ÿ 2AI ÷ 3Oh

"ÿi% : "t _J

.ÿ-ÿ

T= ÿ,oÿ;=13ÿ 3z3

o. il tool clÿ.

28

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Z4. A ba!loon.is heated so that: itw!ll expand.Ihitially; thevolume is 56mL atÿ If the balloon is heatedso', ÿ that it expands to 130mLo wha_t isÿthe new t_emper lature]n the balloon i/ÿ-n deorees Ceÿ

::-:,7 ÿ<'<+ V:.:ÿIÿo-L , , , % ..--, <.<. ÿ<ÿL. ÿCÿt-. ,

• ÿ!lli-ÿ , { ' ÿ fl.olÿ I'lrÿi -+-':. --" -: _ ,in .-- .. liii

:ÿ -. Slll i.

L

'25, ÿre if o22ÿOL saillple at IZÿ.ÿOkPa is reduced to 1.2ÿL ÿsuming that thlÿteillperlzfui'e

I : ' 'ÿ11 IlOL' ' ÿII i '. L ' IIÿ'ÿ ':'II ' " ": : ''ÿ I>ÿ.- "Z :,. < ::-" "'

:.. 7¢200=

Name of Gas Law used here:i

Laughing gas is a mixture of dinitrogen monoxide-arid Oxygen. If the total pressure is 1.2atm, what is the

partial prÿsure of dinitrogen mo.noxide given that the partial pressure of oxygen is 0.45atm? ,

:1 . ÿ .ÿ

,- O.-l

the new pressure after the temperature was increased?

The Kelvin temperature of a ÿas was originally doubled. If the initial pressure is 740mmHg, what would be

iName of Gas Law used here:' ÿ"

v ,

.>..

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27

Nlill ill I[lllll Iil • l

• ",..: .: J

"t - "<ÿ'ÿT (-I1

.t

Graph #1 :The Relationshipbetween Volume and Pressure

of a Gas

Graph #2" The Relationshipbetween Volume and

Temperature of a Gas

0 20 40 60 80 100

Volume (mL)

16. Which graph represents Boyle s Law. ÿ ÿ Oÿ --ÿ! ÿ'I

17. Which graph represents Charles's Law? ÿaÿ ÿ

18. Which graph has the same shape as:Avogadro°s Law? ÿÿ "ÿ

19. In Graph #1, what is the pressure on 20mL of gas? ÿ" 5 ÿ_

20. In Graph #2, what is the volume when the temperature reaches 55K? ÿ-ÿ ÿ ÿ,ÿ

21. Which graph represents an inverse relationship? CÿrLÿ ÿiÿl

22. Which graph represents a direct relationship? ÿ ÿTÿoh ÿ'

Temperature (K)

Sample Problems

Show all work, Be sure to report your answers with the correct numbers of significant figures and thecorrect units. Also, write down the gas law used to solve each'ÿ0blem.

60 .....

23. What is the volumÿ of a sample of gas that contains 1.2m__.ÿol at 780K and 1.3atm?

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26

, iii 10. Howmany millimeters of mercury are in 4,Satin?

• . How,many kilOplaSCals are irL76.0 ÿsi?

/ l'-i.Tp i

Relationships among P, V, T and the Number of Gas Particles

Answer the following questions in complete sentences.

12. If temperature is held constant, as the volume increases, the pressure far a given sample of gas will

OCÿ'ÿ. ? Justify your answer on a molecular level.

,,ÿ,ÿ-ÿ--ÿ ÿaÿ,ÿj ÿÿ (ÿ'cÿ5 ÿ11 nÿ cot,ÿi&eÿ;-wÿ ÿ ÿ\ÿ,ÿ or,-ÿ cÿ,ÿÿ o_ÿ orÿ, ÿ,ÿ

13. How does increasing the number of gas particles affect the pressure of a gas? Justify your answer on a

,sÿ 'ÿe.,'rea,.ÿ.

14. How does the kinetic energy of agÿ change,as temperature is increased?

How does this affect the pressure?

Gas Laws and Graphing• == ",:,

15. befiÿoyie's, ChaHes',andoAv'ogadÿO'lS La'ws.i ' . / ÿi i

Use the following graphs to answer the next 7 problems,

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Gas Laws STUDY GUIDE Due: February 24th.

Units of f,ÿ.asrement:

For the following qÿesHons, use the following answer choices to indicate what each unit of measurement is

USeÿl to ÿe.

A. Pressure "iÿ B. Volume..ÿ/ÿ C. Temperature ----T"

Jÿ_ÿL K "]ÿ 4, kPa ÿ) .7, psi

P 2ÿ atm ÿ/ 5. L ÿ.ÿ_ 8. mmHg

V ÿ3 mL "1-6. oc

Kinetic Molecular TheoryA ÿ ÿ given steam cleaning equipment and asked to steam clean a Tank Carl The interior of the tank car was ÿ

,ÿed{ out & cleared with steam. Then all the outlet valves were shut and the tank car was sealed. All the

xers ÿurt home for the evening and whenÿthey returned, the picture below shows what they found.

J

tlÿ Iÿppÿ-ÿ.d ÿ the behavior of gases to support your answer,

zÿ:ÿ gzÿf ÿ ÿ ÿzrÿsÿ.zÿ W'ÿ tÿ proper number of units and significant figures,

! arm = 760 mmH9 = 101,3 kPa : 14.7 pÿl

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t.• Ideal and Stoichiometry Homework:

i. ÿ _ 1. How many liters of water can be made from".- ÿ 55 ra

lÿd a temperature of 85ÿ° C? ÿgen gas and an eÿ¢€ÿ=ÿÿn at a prÿsure of

2ÿ12ÿ) + Oÿ)÷ 2HzO0

: ,ÿ,ÿ'1-/= ÿ.qÿol

- Iÿ, OSfl = {_1'. I L-.,I-h.bI

2. If you burned a gallon of gas (CsHIs) (approximately 4000 grams), how many liters of carbon dioxide would beproduced at a tÿmperature of 2'1oO°C anÿd a pressure of 1.00 atm?

© "4".

J3ÿwere burned at a temloÿre of Z63°K and a pressure of t:3 atm?

Using thesame chemical equation as in #2, how many grams of water would be producedif 20.0 liters of oxygen

,. • j "] ,s:-

23

i/%ir.lÿll II Iÿ,/VI I,,/y ÿl/rIAi I It.II%.lÿllÿll II It.ÿ1

Example 2: Calculate the volume of hydrogen gas produced at O.O°C and 1,00 atm of pressure by reacting 12.0 g oi •:i

zinc metal with excess sulfuric acid. •

Step 1: Write the balanced chemical reaction.

Step 2: Convert grams of zinc to moles of H2 using the mole ratio from the balanced equation.

Class Practice:

3. How many grams of calcium carbonate will be needed to form 4,29 liters of carbon dioxide? The fallowingreaction takes place at a pressure of Iatm and a temperature of 298K.

I CaCO,(s) +lCO, ) ÷lCaO(s)

,+ •

,1

I

< J

22

,OI,.ÿIIIIIÿLI IJy ÿ,.ÿ,ÿIIIIOUÿIIIIIÿI

Ideal Gas Law and Stoichigmetry gf GasesZdÿ! Gas Law and Stoichiometÿ'ic Problems

In industry and in the laboratory, many important chemical re6ctionsÿinv01vÿe gasÿ.-A common laboratoryexperiment that produces small amounts of hydrogen gas involves the reaction of an active metal with a strongacid. This reaction can be represented by the general equation: ..

M (s) + HA (oq) ÷ MA (aq) +'H2 (9) ÿ "

where "M" represents the metal, "HAI' the acid, and ÿ'&bÿ,'' the salt formed 5etweenÿthe metal and the anion of the

acid,

It is important to be able to perform stoichiometric calculations for gas reactions. Stoichiometric calculationsinvolving gases are identicaita those involving solids and liquids with one important exceptl0n. For chemical ÿreactions involving only solids and/or liquids, the amounts of reactants and products are usually expressed in grams;however, for chemical reactions invoMng gases, the amounts of gaseous reactants are usually expressed in liters.To perform a stoichiometric calculation, the number of liters of a gas reactant must first be converted to molesusing the ideal gas law. For stoichiometric calculations in which the number of moles of gas products has been !iiÿicalculated, the volume can be calculated using the ideal gas law. ÿ:ÿ

Example 1:at 304K andapressure' of 1.02 atm. How many liters of ammonia gas are formed?

Stÿl.' Write the balanced chemical reaction.

Step 2: Convert liters of Nÿ to moles of Nz.NOTE: Since the gas is not at STP, you must convert uÿing the Ideal Gas Law before you can do Stoichiometry!!!

Step 3: Convert mo!es of Nz to moles of NH3 usiÿ of the balanced chemical equation.

Step 4: Con_ vet1" rpeleÿ nÿ NHÿ to ÿ using the ideal gas law. i:ÿ

PV = nRT:

\3.00 liters of nitrogen (Nz) gas is reacted with excess hydrogen (He) gas to form ammonia (NHÿ) gas ÿiÿ

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"Homewnrk far Ideal Has Law

Jÿ

,!

16 L of carbon dioxide is at a temperature of 45° C and a pressure of 85 kPa. Calculate the number of moles of-present. ÿ -'---" ÿ t

i"x= 't.

The pressure inside a balloon filled with 168 g of nitrogen (Nz) is 95 kPa with a temperature'of 15° C. Calculatethe volume of the balloon.

Z°

f compressed oxygen is at a temperature of 330 K. If there are 7.3 tools of oxygen in the container,calculate the oressure (in arm) inside the container.

?V=nÿO-T

4. What mass of carbon dioxide will occupy 5.5 L at 5.0°C and 0.74 atm?

10ÿ mols of COe ÿpresent, ÿalculate the temperatur? inside the cave.

V = ÿ,ÿ,oÿL "ÿÿ

-r° ÿ. ÿo T= 30 ÿ =

If a cave has a volume of 5.4 x ÿI0ÿ I of air at a pressure of 140 kPa and it is determined'that there are 3.0 x

i Ill Ill Illll

: iÿt!;"

Liÿ;;.

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GUIDED PRACTICE:1. Calculate the number of moles of oxy-Givens and Unknowns:

)

len in a 12.5 L tank containing 250 atm, measured at 22°C.Equation:PV = nRTSubstitute & Solve:

v= i ÿ_,b'-L

n= ,

R = O.Oÿ?.tÿ

T: 2-q-'ÿ'C+ÿ'15 --ÿqÿ K

+

= ++:

b

+

in theGivens

methane gas (CH4) is introduced into an evacuated 2.00 L container at 35°C what is the pressurein atm?

Equation:PV = nRTSubstitute & Solve:

..

n=

R=

i..+,ÿ

kPa, calculate the volume of the balloon.

Givens and Unknowns: Equation:PV = nRT

P = 100 I(,ÿ)oÿ Substitute & Solve:

n: 0.Sq

R :ÿ.ÿ1 ÿ-ÿ

T=+n+mÿ+ = sm

. A balloon is filled with 0.34 moleÿ of pure nitrogen. If the balloon is at 37 :C and is under pressure of 100'

= ++,+ÿ$87q.= ++ +

+ • t

:++.;ÿ;-'+++ÿ+ : ?:,F+," .... ]+:+"

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Ideal Gas LawAn ideal gas is one that fol,ows the gas laws at ÿ]) C0ÿ;ÿ/)ÿ lÿÿj

ci

Such a gas would have to conform precisely to the assumptions of ]ÿ'nÿ'ÿ,

Asÿou probablylsuspect, there is ÿ for which this is true. An ideal gas, vÿ7 exist Nevertheless. at man co i ÿ - I '...... , y nd't'ons of temperature ana pressure

YÿZLÿ ÿaÿeÿ _ behave very much like an ideal gas.

'li

.!

An impoÿtanÿ behavior of reaJ gases that di,ffersÿfronÿ ÿrhat of a hypothetical ideal gas is that real gases can be_! I OÿL,ÿi ÿ and sometimes ÿO|;rÿ ÿ by cooling and by applying pressure. Ideal gasses

cannot be. For example when water vapor is cooled below 100 C at standard atmospheric pressure, itcondenses to a liquid. The behavior of other reaLgases is similar, although/awer temperature and greater

pressures may be required.

****Gases behave ideally at I%!ÿ "ÿlMzÿp_l-O-ÿ.l-ÿ_

If we look at one side of the Combined Gas Law:

p V+"

nT

and solve it for one mole at STP, you would get a "constant" (symbolized as R).

= 8.31(L. kPa)/(K- tool)(1 mole)(273 K)

We call this the ideal gas constant (R):,<

If pressure is measured in:

kPa

arm

mmHg

tort

The ideal gas constant (R) is:

8.31 (L' kPa)/(K • tool)

0.0821 (L "atm)/(K. mol) ,

62.4 (L- mmHg)/(K - tool)

62.4 (L - torr)/(K • tool)

SO,,,

PV-- =R ORnT

PV = nRT

Label the variables:

n: ÿb% ÿ"

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i • 11 :

i:i H°m°w0rk f0r o0't0,, L0w nf p0rt,01 pre,s0r ,: or each problem, calculateÿ the pressure using correct units. Box final answer. SHOW ALL WORK!!

1. Oxÿ/gen gas from the decomposition of potassium chlorate, KCI03, was collected by water displacement.

2KCI03 -ÿ 2KCI + 302,

What is the partial pressure of oxygen collected if the barometric pressure (total) was 731.0 torr and,the

vapor pressure of water at 20.0oc was 17.5 torr?Pÿ: ISl.Oÿr

P2: t'i.ÿ-ÿrr P,o,.,,: ,.'lÿl.O-ÿ-r-ÿ n.s-tÿrr

, A sample of nitrogen gas was collected over water at a temperature of 23.0°C. What is the partialpressure of nitrogen if the atmospheric pressure(total) was 785 mmHg and The vapor pressure of waterwas 21.1 mmHg?

3. At high altitudes, pilots have to supplement their upply or oxygen. ÿn this mixture, there are oxygen ana

nitrogen gases. If nitroqen's partial pressure is 250mmHq, calculate the partial pressure of oxygen if the

total pressure is 710mmHg.

, Saturn's atmosphere is composed of hydrogen and heiium. If the p t" I p f he gases are

25.0atm and, l.2atm,respectively, what is the total pressure?

'17

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1 .

Dalton's l]as Law of Partial Pressures

Partial pressure of a gas in a mixture of gases is the pressure which that gas would exertif it were theonly gas present in the container. ,

Dalton's Law of Partial Pressures states that tBe total pressure in a gas mixture is the sum of the partialpressures of each individual gas.

Ptot'al = Pgas a + Pgas b + Pgas c + etc

Daiton's Law of Partial Pressures assumes each gas in the mixture is behaving like an ideal qas.

Pgas a

1laÿ, pre.sUÿ

,+

'+

Pgas b

3abn pressure

i

.

.

Example Problems ' '

Air contains oxygen, nitrogen, carbon dioxide, and trace amounts of other gases. What is the partial

pressure of oxygen [Podgy,) at 10£3kPa if the partial pressures of nitrogen, carbon dioxide, and other gasesarÿe 79.10kÿ0.040kPa,iÿ ÿ_o ÿ_ and 0.94kPa,.ÿ,,r respectively. ÿ)ToT = ÿN "/''pÿozÿ "ÿ- + ÿoI.

A mlx-fure'of gases contains oxygen, nffrogen, and helium. The partial pressure of oxygen is 2.latin. The

partial pressure of ÿin ff21atm, and the partial pressure of helium is 7.80atm. Determine the totalpressure of this mixture.

rd-

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Ptÿtÿl

J :

4alan pÿeSstÿe

g ÿ

/

,

V l =/J.I::)L

kl ÿ_ --- 7

Aÿ sample at 25 °C and 2.00 atm of preÿsurÿ contains 0.5 mole____s of a gas. If an additional 0,25 moles of

gas at the same pressure and temperature are addeldI what is the final total volume of the gasÿ"-'--

Vÿ

When 250 mL of O2 is heated, there is now 310 m__L 02 at 273___ K. What is the_original temperature in ÿC?

./

4. Gas law:

t-ÿmperature in there is now 320K. Should you worry that your balloon will pop? ÿ-ÿIlll

1'€.. = ÿlÿ,F--,

Your Valentine's Day balloon has a maximum vol_ume of 5.5 L. Your balloon originally has a volume of 5.2 L__ at

288K. When you walk into your Chemistry classroom, you realize that they have finally fixed the heat. TheSupport your

answer with calculations!

"T, =" ÿY,, ----"

'.ÿ_ ÿ ÿ ÿ.

Tz = ÿ','ÿR z.ÿv, ,'--',ÿv.-

5. Gaslaw: ÿ'2ÿ0ÿ'ÿ

Vÿ= S, q"! "1

You have 2.00 L of dry He at STP. How many moles is this?

The pressure on aneÿhetic gas changes from 15,0 atm to 6.0 atm. If the original volume was 12.0 L, what

willbe the new, volume of, theanesthetic gas after the pressure has been decreased? "

}%

15

, €1,'i.. :,

, l,l:ÿmÿl

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Homework- Boyle's, Charles', and Avogadro's

Boyle's LawMagnet Summary

Laws Practicÿ1

General Graph for Boyle's Law

: g: i : [ : ÿ : ÿ " " I1 11::I :I "ÿ :l:'l[:':ÿ : II

State Boyle'n Law,

°ÿrÿ ÿ0ÿ=, I Boyle's Law IEquation for Boyle°s Law

t

Charles's Law

Magnet Summary

State Charles's Law. General Graph for F-]ÿrles's Law

(ÿ¢ ÿ ÿrerÿp. Charle.s's Law I Inverse or Direct?

Equation for ÿarles's Law

First, identify which gas law you need to use to solve the problem and then solve for the unknown. Be sure

to show all work. For every problem, report your answer with the correct number of significant figures andthe correct units! Remember, temperature must be in KELVINSlll

'ÿ,L= "?

Vz, 'z:col_.

Gas law: ÿ)Oÿ. ÿ

A sample of carbon dioxide occupies a volume of 3.5._._ L at 125 kPa. What pressure would the 9as exert if

the volume were decreased to 200 L? Assume that the temperature remains constant,

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: :ÿ Example #3:

..

J

Do gases A, B, and C have the same or different volumes?

For each gas, T= ÿEÿI"R (120"F)P = 14.7 psia

A B CAmount: i Ib mole 1 Ib mole 1 Ib mole

MASS:. 32 Ibm 2B I1ÿ 71 Ibm

i >,

. •ÿ..

%,

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Avogadro's LawAvogadro's Law (Avogadro's theory: Avogadro's hypothesis) Is a principle stated in 1811 ,ÿ:by the Italian chemist Amedeo Avogadro (1776-1856) that "equal Volumes of qases atlthe same temperature and prÿ,ssure contain the same number of molecules reqardleSSlof their chemical nature a.nd physical propertms' .'This number (Avogadro s number) is6.02 X 10ÿ3. It is the number of molecules of any gas present in a volume of 22.4 L and is

the same for the lightest gas (hydrogen) as for a heavy gas such as carbon dioxide or bromine.

Thus, the molar volume of all ideal gases, at 0° C and a pressure of 1 atm., is 22.4 liters"

Or to put it another way, "the principle that equal volumes of all gases at the same temperature andpressure contain the same number of molecules.

nl nz

V = the volume of the gas

n = the amount of substance, in moles, of the gas

Example #1: 5.00 L of a gas is known to contain 0.965 re!l. If the amount of gas is increased to 1.80 real, whatnew volume will result (at an unchanged temperature and pressure)?

t ,-ÿmoi

JI .-.-.- +

03--" \.ÿ0 tÿolxomple #2: A cylinder with a moÿ,able piston contains .005 real of helium, He, at room temperature. More

helium was added to the cylinder and the volume was adjusted so that the gas pressure remained the same.How many moles of helium were added to the cylinder if the volume was changed from 2.00 L to 2.70 L? (Thetemperature was held constant.)

O,OlbS"

• +

;+

/

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>,

l

12

+

+ The Effect of Temperature changes on Volume- Charles's Law

!I'ÿÿ.AS the gas inside a balloon ÿXÿtr'}ÿÿ) , the average KE of

moleculesÿ -- -

With fewer and 'less collisions, the gas molecules move ÿ-Yÿ

together and occupy a ÿvolume than they previously did.Theÿ (ÿ\\I+ÿYÿ ÿfX'ÿL_ÿLÿ assuming no change in the amount of

gas and pressure.

Tt

O+C

. , !

• .27ÿ0 t00+,C

OK 2?34( 4(iqÿK '. :'

V1 V2Charles' Law 1

,/

T2

Charles law states'. At a constant pressure, theto the "lre_wÿ+ÿ0c)ÿYÿ in Kelvin.

J |-

r Chades

.ofagas iS directly pfOpIJ£-lÿIgO- )

&cÿ 6-ÿt, -1V,;s i $ o

-r, -- @ÿ-ÿOY,

q?.. = "Z,

"Tÿ ÿ xÿÿ(>Y'-

GUIDED PRACTICE: Temperature must be in ÿ., Pÿ\ÿJ i Iÿ +1. Thÿ temperatureofa 0.65L sample of carbon dioxide gas is 580K. If the pressure remains constant, what

is the new volume of the gas if the temperature increases to 1300K?

"Tÿ.= ÿ.

kJQ_-ÿ

2. A balloon has a volume+ of 5.6L.at,a temperature of 98°C. If the volume of balloon increases to 9.5L, what

will be the temperature of the gas in Celsius?,Aÿme that the pressure remains constant.

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Rnyle's Law and Charles' Law

The Effect of Changing Size of Container- Boyle's Law

WHAT IF...temperature and moles do not change and we just look at the relationship between pressure andvolume. Our equation would look like this:

PIV1-- P V2 Boyle's Law

Boyle's Law states that at a constant temperature, the volume of a gas is inversely proportional to the pressureexerted by that gas.

P VLa

Pi

Examples:

CL

b.

C.

If a gas is compressed from 2L to 1L, the pressure willby a factor of 2.

If a gas is expanded from 1L to 3L, the pressures willCÿexTÿ-tÿlÿ_ ÿl by a factor of 3.

Gases cool when they expand and heat when they compress.Why?ÿ-- ÿLÿ.ÿ.ÿ.ÿ ÿ--CÿO)ÿ'ÿ nÿ ÿ..ÿ

Thus, if you forget to wear your suit m space, you

i - ÿ ÿ.,,ÿ,

/Example Problems1. The pressure of a 3.5L balloon was determined to be 1.Satin. Assuming that the temperature remained

constant, what would be the volume of the balloon if the pressurewas cleÿegseÿto OA5atm?

%/2. 2.ÿ" At 45.ÿa certain container ÿf as t e volume of 580mL ure of 980ÿmHg. What would be ":'i,:;ol e a g and 4F ". ÿ "T¢.,,ÿ ,ÿ ne't Cÿ'iOÿ ..." _,, the new v um of the gas t 250 mmH ÿ0 . " !"ÿ

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Soda Can Activity

OBJECTIVES1 " Students will demonstrate the effects of air pressure.

• Students will demonstrate that as a gas is heated it expands and as it cools it will contract.

MATERIALS• an empty aluminum soft-drink can• a 1000 mL beaker• a pair of beaker tongs• hot plate

PROCEDURE1. Fill the large beaker with ice cold water.2. Put 15 - 20 milliliters of water into the empty soft-drlnk can.3. Heat the can on the hot plate at the highest setting. 'When the water boils, a cloud of condensed vapor will

escape from the opening in the can. Allow the water to boil for about two minutes. Do not let all of the

water evaporate.4. Using the beaker tongs, grasp the can and quickly invert it and dip it into the water in the pan. Be careful

of. the hot water!5. Record your observation. •6. Clean up your lab station.

OBSERVATION

CONCLUSION "Explain why the can was crushed (discuss the relationships between pressure, volume, and temperature).you have to heat the can up in order for the can to be crushed?

Why did

bcanne-(:] uy L, ambcannerir I III

Homework - Combined Gas Law Practice

Z': 1 : •

1. A 5.00 l- air sample at 170 K haÿ a pressure of 107 kPa.raised to 548 K and the volume expands to 7.00L?

What is the new pressure if the temperature is

T

-r, ÿ,oÿ, (ÿlÿ,)(ÿ.o J (7,ÿ'ÿ ÿ_ ÿ4ÿy,ÿ,ÿ

2. ...... . . Th pressure increases to

1980mmHg as the temperature rises to 398K. What will be the new volume?N/\, ÿ.ÿm---'

3. The voluÿe in agas f,iieci ba, aon is 30.0 L at 40 C'and"3-.6ÿatm o_ÿ pressure. What volume will the balloon

• ,o ÿ.ÿ ___ÿ__ÿ O,ÿ(l ÿ ÿ)

\ -4,gL

Vÿ, = b,S-kn, =1,ÿol

4. A container has an initial volume of 4.5 L, a pressure of 450 kPa and is at a temperature of 15 °C. If the

container is expanded to 6.5 L while the pressure is decreased to 125 kPa, find the resulting temperature.

8

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2o The volume of a gas at STP is 22,4Lo At 12oc, the volume of the balloon changes to 55,0L. What is the new

pressure?

Givens and Unknowns: . Equation:

n,= [ -lÿ€lb'ÿ

' I II

v2= 5ÿ,OL

Tÿ= ÿS-ÿ " ' .ÿ

Substitute & Solve: ÿ,

J3 .ÿ..

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L.li't"ter or

Number

n*

T

2*NOTE:

Variable Name Unit

If "n" is not given in a problem, assume it to be 1 mole.

onversions *dÿ@ ÿ

' ÿs

K- c ta'lS

Temperature must be in

Guided Practice:

Remember: STP = ÿ arm and ÿ ,ÿ

.

Givens and Unknowns:

,: I.ÿ.ÿ

v,: -1 ÿ'-cO L-

n,- 1-,ÿ\

T,: ÿq¢> iq

Pÿ: O.gO ÿ'ÿ

Vÿ = unknown

nz: ÿ IÿOÿ

T,: ,P.ÿ,oY-..

A hot air balloon has a volume of 75OOL at 270K and a pressure of 1.2 atm. What will be the volume of the

balloon if the pressure changed to 0.90atm and the temperature decreases to 230K?

Equation:

_..l-'.l

Substitute & Solve:

r

1

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!ÿ COMBINED GAS LAWe Combined Gas Law helps us explain what happens to gases ÿsfhe pressure° temperature; and volume changes in

'espect to moles of a substance./

Avogadro'sLaw

CombinedLaw

I-ÿHer or

Number

P

• !,, .ÿ ,

V

Variable Name Unit

L

Ornÿm3

Conversions, :

.--I ÿ'ÿ

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ruth? average speed of oxygen molecules in air at 20°C is 1700 kin/h, At these high speeds° the odors,, ::' ÿiorecums trom a not pizza in Washington, D C, should reach Mexico C"ÿ. ;z ÿL ; .A_ : ÿ ÿ'ÿ' :d ' " • ' ,Jy m aoour luo minutes. Wffÿiÿiÿoesnt th,s actually happe_n? ÿ;'ÿi'ÿ '" uÿ_ÿ mÿnutes. Whÿ

Questions:

A, What happens when a closed container is inflated?

•

A gas inside a bicycle tire exerts a pressure of 35 pounds per square inch (psi). How much air must be

pumped into the tire to produce a pressure of 70 psi?

• °

• What happens to pressure when a closed container is deflated?

(Note: eÿas particles.move froÿ re.qioh of hiÿher .......... ubÿ ÿL\ÿ o ÿ ÿ,===urÿ ro ,ower pressure until equilibrium is reached)

.

HOMEWORK Day 1 - Practice Problems on Pressure & Temperature ConversionsShow all world Record your answer with the correct number of significant figures and units!

Calculate the pressure of 1.3atm in mmHg.

.

5ÿ

2. Convert 56kPa to psi.

3. How many atmospheres are equivalent to 230kPa?

What is 560K on the Celsius scale?

C..=!Water boils at I00°C. What is the boiling point of water in Kelvin?

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viar of Gases and the netlc Theory

motion, iS called 2ÿ.ÿ[e,-ÿ¢ÿ en, Q3".ÿH

The Kinetic theory states that "the tiny particles in all forms of matter are in" J

Watch the video segment (Kinetic Molecular Theory in the video staÿard Deviants School Chemistry;Molecular ÿoÿtÿ,ÿ on Discovery Education and fill in the missing information ÿ ,, ÿ, ÿ-- ÿ

bttlÿ:/lapp.discoveryeducation comisearchÿNtt=standard÷deviants÷on.,

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4. The average kinetic energy of the molecules of a gasis proportional to the _-ÿm £ÿ,,ÿIÿLÿ-LLÿ'Pÿ,

5. Every timed molecule collides with the wall, it exerts a "ÿ-'ÿ

on it which we call ÿreSÿ ÿ" ÿ ' '' ÿ • ,, ÿ -.iÿ'

Applying this knowledge we know... •

_tGases fill their containers regardless of the __ÿ and

\/ÿÿ. of the containers,

Because there is so much space between particles, gases are ' ÿ

pÿ,%ÿ,l ÿÿOÿllÿi ÿ, . Because gases dr,

(ÿ/'ÿrn.ÿ::ÿlÿ,ÿ . they areusedinautomobile Iÿ-\Y'ÿON ' and

other safety devicesdesigned to ÿ,ÿ'ÿ0ÿ the OYÿO.Iÿ.ÿ of an

mpact.

i ÿ ÿ ÿ ÿ 1 1 1 are perfectly pÿOÿTÿ . Thismeansthat during

collisions kinetic energy is transferred without loss from one partic!ÿ to another, andtotal kinetic energy remains (ÿ(ÿrÿxÿ'ÿ ÿ . ÿ "

Basic assumptions of the kinetic theory as it applies _to gases are:

1. A gas is composed of particles, usually molecules or atoms that are ÿ0ÿ- (ÿ0ÿ'ÿ from one

another in comparison with their own dimensions. Particles are relatively far apart'from onÿ another andbetween them is eÿnÿ ÿxÿ¢ÿ. .

2. Gas molecules are in (ÿ/3nE,ÿlnÿ" tTLVÿh'3 13%ÿ tr) . They travel in straightpaths (unless they collide with a wall of a container) and move independently of each other.-

3. The molecules exert no force on each other or on the container until they _ÿ ÿ with eachother or with the walls of, the container. ÿ, .ÿ

... -

Pressure i::

1. What is the definition of pressure? " ll ] ÿ

eÿd bB ÿi!.

3, Which shoes create the most pressure? How does changing the area of contact affect the amount of pressure

exerted by an object? ÿ,iÿt, ÿ,ÿ)

og ffessÿre e, evkd 0n ÿ ÿbÿd4. What are the units used to measure pressure?

5. How 1do I convert between units of pressure?

6. How many kilopascals are equivalent to 880 mmHg?

7.

gg'Oÿ,ÿ145 ] I Of. ÿ kP<

Calculate the number of pounds per square inch (psi) that are in 2.60arm.

lTemperature - ALWAYS usÿ absolute temperature (Kelvin) when worÿinÿ with gases.

Conversion:

K = °C + 273

_ÿatm= ÿ0 mmHg= I0i. 5 kPa= 1 g7 psi

: g-ÿ

"2]]ÿ

>N

;2%

:;:IN

:{

Practice problems:

aaÿ aÿ3How much is 75°C in Kelvin?

., : { :

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