study of gas and study guide

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~ Honors Chemistry

Learning ObjectivesUnit 8 Test

Gases

1. J(now the mathematic expressions for and understand the relationships within all relevant

gas laws. Be sure to specify which conditions, if any, are held constant.

(a) Boyle's Law f\\l , ~ ~2.. \ J 2. w\'\t"\t- n . -T c,s~ ne\t- ? ~_f\ DSt:.. C(:)\\~"\c\..\r\..TI \'Z.

\}O\Uffit ~ ().h~CJ\\J~~ --\t\'f\~ t Q\L ci\f~e."\ \\...~\t':\Ntc~..

(c) Gay-Lussac's Law .f.L - = - - ?z.w\Jt'\t ~~'(\ CL,t. . ~Q\~'t().S\-t.T. \z.

y\e~G\ t ~NJ'::.Cl\0 'I t-\tn,?

c,st- d.\RC::"'I\ '-\ n : \ \J . . . - te :d , .

Cd) Avogadro sLaw ~}"C- \1 - :2 - wYle:\t.. ? ~" u..\t f"()"~--\.US'IlnI n '2 . . \ , ;

\!D\\X'\\t ''l, , - \ - ~L T Y.-::l

,. .(h) Dalton's Law of partial pressures

(i) Graham's Law of EffusioniDiffusion \\C)\C)S ~~ ~

rna\es.r n1JSS A .

2. Be able to perform Celsius to J(e1vin temperature conversions.

e.g. K =C + 21"~

e.g. In gas law problems, the temperature should always be in which unit? I ( ,e : \'\j\\\

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3. Be able to recall standard state pressure and temperature conditions/or gases. ~r\?=- \. aG~ (Joe

4. Be able to sketch and interpret graphs of Charles' and Boyle's Laws.

e.g. Sketch a graph of V versus T assuming constant pressure and moles of gas. At what value

does the line you have drawn intercept the X-axis? What is the significance of this value?

At -z . . e , c ; '0::\'\)\n O --\ . \ .f i

e\\e\~~ lena\" \0"~ 't\'\~ ~(:t b~twe.t\

\'~\-t\ t-\e~ ~C)~ - \ - \ 2 ) zt,o

~\"c.ttct~

Te"f>~\)\t. l\:..)5. Be able to peiform calculations related to each of the gas laws.

e.g. What pressure, in units of torr.....would a sample of Xenon gas exert ifit were compressed

from 4001 mL to 3002 mL at constant temperature, given that the initial pressure was 750.1 atm?

150\ Ck.tm. -::. 5.1 D\y., \c ? 1-0\\

(5.,a\ X.\cr 1-cr,\ l\CO\l'r\L') = - YL (~'L. ~L)

\ \ = '1 . . " : . . '1 . . 5 '1C O ' f. . \ 05

to,{"]#e.g. An almost empty aerosol can has an internal pressure of 1.030 atm when the temperature is

.\Y~ 2S.00C, What would be the pressure in the can On kPa) ifit were placed in an incinerator fordisposal, \Yhich would have the effect of raising the temperature inside the can to 1500.oC? Why

is the incineration of aerosol cans not recommended?

L0~a o:l\"'f\ - = . \ O~ .0 '? J L~

(\O~ ,a~ \r -..V~') _ P2.

2~~ K \J''?J \.(..-7)'P2- -- \.0\ U . q ~\'~~,

kh\:. ~a0

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'--') e.g. The average velocity of carboni dioxide molecules at room temperature is 409 m/s. What is

" " c : : : t ' " the molar mass of a gas whose molecules travel at 322 mls under the same conditions? ~ r ~ I - - - - - -~ C ) c ; ft\I~_ .: : : . n f t n - " $ ) 8 _

4-,0\\ 'r "--7\\"'1">0.:;:,~ 'B - = - / \ . ( ) \ W~

e.g. Calculate the pressure inside a tube, given that the tube's volume is 5.0 L, its temperature is ~

23C, and it contains 0.010 mg of hydrogen gas. btO\D""'~t\z..(. \ ~ ] ' rr O L ~"-\0 0 \. ~~ '\ '\...'D\\.o~

P (5 ,0 L)'= ' (4."lo~\\) tl\OL\a,Cj~L.\"'-25\1o K-') .

\ p - = - 2.'\\v : \05cd~-~

e.g. Calculate the molar volume (i.e. the volume of 1.0 mole) of an ideal gas at 1.0 atm and

25C.

lLDCd\'T\ ') \j ~ l " d~()l~ O,Q~:)2.\Jl2.~b \(..')

\ 'J~ 2A.5 ~}~< -

l'I e.g. A 0.109-gram sample of a pure gaseous compound occupies 112-mL at 100.C and 750 torr.

P What is the molecular weight of the compound? \ \ \Q. \\2 L ~1~ ~ 0,~ \r.Q ' \e.g. The average velocity of ammonia (NH3) mo!ceules is at room temperature is 658 mIs. Howfast would hydrogen sulfide hastravel under these same conditions?

\Cde"z.~ - = - \-"1.0'0\ C \: ..-\ - - . .----:=..---_-~--\lo5'b "'Is 34 ,0/\0 , ---'7 I\Cjjt.\-I,o, 4\05 Is 1

e.g. Ethylene dibromide (molecular weight = 188 g/mol) is a volatile liquid with a boiling point

of 109C at 1.00 atm pressure. What is the density of this gas under these conditions in grams

per liter~ ~


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e.g. An unknown gas containing only carbon and hydrogen was found to contain 85.63% carbon

by mass. At STP, the density of the gas is 2.50 giL. Determine the empirical AND molecular

formulas for this compound.

< 05.\.o~ ~ ~ -7 ..,.\3 \nO\ c : . , -7\

\ L \ . '~'l ~ \-\-7 \-1 , 'll.o n-o\...\-\--7 '2 - _

(Loa M m ~ L\.JD L ') '=, \\ lO\CJn::. ().04'1"'\ rnol ~L L 2 . ' 6 0\"\' " 0 - = - \ l.~'0 " t ! " - - ]

\\ mOL\-.j~ )

6. Perform calculations related to mixtures of gases.

e.g. Air contains 02, N2, C02, and trace amounts of other gases. What is the partial pressure

of oxygen gas at 101.320 kPa if:

PN2 =79.10 kPa Pe02 = 0.040 kPa Pothers= 0.94 kPa

\""", '" \DI.~20 '< -P tA . ~ "1 "t.\0 l:.Pck TO. 0


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e.g. A 3.40-L tank contains 480.0 grams of oxygen gas and 80.00 grams of helium gas at

2S.00C.

(a) What is the partial pressure of oxygen gas?

1 -e o .o 't 02. - = : . . \ ~ . 00moL 0:L . .

P o ~ C ? > , ~ \ ) L ') ~ (\5. 00 tnct.~ D ,Ot:{l. \X L~'t) i)-7\PDL'::. \DI .9 OC1l1')_._

(c) What is the total pressure inside the tank if the temperature is decreased from 2S.00C to

I5.aaOC?

8To-r::' \D-, q -t \ ~ 0 ," o:.h-n. - - = - 2.'5 \. b < X X m.

(2.'5\ .b Cdm') - = - . ?2- -7 \- - f ' - " --::..-2-:~-3-~-L\-~-i-tn-'12.~'O - Le~\C. . z. . \7. Perform calculations relating molar volume, gas stoichiometry, and the gas laws.

e.g. Small quantities of hydrogen gas can be prepared in the laboratory by reacting zinc with

hydrochloric acid according to the following unbalanced equation.

_'_Zn(s) + ~HCl(aq) -7 _\_ZnC}z(aq) + _\_H2(g)

In such an experiment, 454 mL of hydrogen gas were collected via water displacement at 23.0C.

The total pressure of the gas sample was 712 mmHg. The vapor pressure of water at 23.0C is

19.8 mmHg.

(a) Ifthis reaction typically has an 85% yield, how many grams of zinc were required to produce

this quantity of hydrogen gas? ~ 'V,.


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e.g. A 22.0-gram sample of impure sodium chlorate was heated until decomposition was

complete according to the following unbalanced equation.

~NaCI03(s) ~ ~NaCl(s) + ~02(g)

Assuming 100% yield, what volume does the collected oxygen occupy if the reaction was carried

out at STP?

22..Q CL~o...\..\.()~('. rcd.~\.9oY3 < 1"0 1. 01.. '\{-~~~~, \ "'-r to.') '1- 02,t't)

4,22. LClz.(~~LL{)D l~~~~'t\~~Ji6J "" 3'0.\ % ~ ~ \ ) : , Cpu

Ole our-\"\'-\-. - = b < 0 4 \ % = . ) ( \00 ':::.\ ~'D.~ o l d\" " - ~ 55-CO \

The following will be PROVIDED for you on the test:

1.00 atm = 760. mmHg = 760. torr = 1.01 x 105 Pa = 1.01 x 105 N/m2

Universal gas constant (R) = 0.0821 L'atmimol'K

***Be sure to review and study all relevant notes, quizzes, and labs.

Honors Chemistry 2011-2012 6

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