Unit 13 Notes: Gases
Kinetic Molecular Theory -Assumes IDEAL conditions
- mix easily
Have
All particles have the same average
Particles in a REAL gas
Have tneir
own { D[U-N\ (
rr-ttfaf ,|
,
each other
Gas behavior is most ideal
-
Low pressures
High temperatures
ln non-polar atoms/molecules
Characteristics of Gases
cases
IVDAI^f{
o.." -P\ird s
to fill any container
rlr.
Have very low
can
P+
oe CAfnDY eSSeC
----------:-,,
*,ja
;,"r* D'Sus'on""
EtPusion
h anolher
Diffusion
. rhe SfflG-LL€ C
.
".e..;;;;
G$p'sr,,er1)
P{-utsr.'
Undergo
o
v.
Spao
6rL)
the particles, the
they diffuse
Effusion
Temperature: nr-wnvs
r= oC +
usr K€
Zn3
L\
I
N
"L
=
WHEN WORKING WITH GASES!
Y-,
- 213
Pressure: Created when
Pressure =
Measuring Pressure
rometer
Manometer
Units
Ba
r
IOI
.
3
a
KPa-
' +t D --+13
t--Ihese
cx(
e
uLL e-e,;-a+
torr
lr^th olh.er
a
to
.
I a+.rn
t.{.a ys\
?LoO
Ir
o
.
STP
.
-
.
Temperature:
Pressure:
la*m of
O'C or Z73Y
lOt.
Pressure Conversions
.
]
pp^
The average atmospheric pressure in Denver, CO, is 0.830 atm. Express this pressure in mmHg and kPa
tr30.8
i t o-+m
.
i
Convert 300.7 kPa into
.
mmHs
34:.+ t<?al+LoOmmUq
.ror3.-1apa'
) LZSrt
I
l^-lg-l
o.S3oartrt rot.3KPa
o.83o
tot.3KPa
i I ahn
Bq.oB rPa
kpa
psi lOo.?k?a
tBcl
t4.?ps,
Itor.gxPa-
_
-_
,. PSi ]
t2
m l--. L Cm'
rCoOmL = \L
You must be able to convertl
ard
lrnL=lcrn3
Alwals checK
IT'STHE LAW! GAS LAWS!
Boyle's Law
?rt
Formulalt'Jl
=
\Dt^f o.nSN e( +P
ncg-ke. Strre \I
Ir'alches +he
re.\atronSh\P tl
h,.
Relationship
conrt-t-tremDe(At,tfe-
*
MaS\
Example: Dlvers get "the bends" if they come up too fast because gas in their blood expands, forming bubbles in their
blood. lf a diver has 0.05 L of gas in his blood under a pressure of 250 atm, then rises instantaneously to a depth where
his blood has a pressure of 50.0 atm, what will the volume of Bas in his blood be?
cgoxg9=E=tl
"l-=(
5o'o
zsoa+rn Pz = 5D Da+m
\r=o.o5L
P, =
Charles'Law
\1
vl
Relationship
-
conrtunt
\ Yi Z-
lDrrac\ t t
M*:l
r,
coue({ f
'C+oK
MaSS +'QresSL,,.(e-
Example: Some students believe that teachers are full of hot air. lf I inhale 2.2 liters ofBas at
and it heats to a temperature of 380 C in my lungs, what is the new volume of the gas?
\j , --
T,
ir--z
LZL
=lB+ 213--2at
6
Tz=38+273=3llK
z.L
a
temperature of 180C
zqt =!a
3tt
.=
Gav-Lussac's Law
Formula
n"rutionrr,ip
?)z
1
W
-f '
T)'1( f e}
1'z-
Tt
P
Constant
Example: lf a gas in a closed container is pressurized from 15.0 atmospheres to 16.0 atmospheres and its original
temperature was 25.0 "C, what would the final temperature of the gas be?
lJr=t.Uatrn
P, = la Alnl
J,
= 2b+773= ZqZY,T" =
-;_---''_r
lt! --ltu.5
tL
tb
2qb
(
K
Dalton's Law of
,or^'rM
u.nt*
Remember! Vf e
I
Example: Blast furnaces give offmany unpleasantand unhealthyBases. lf thetotal air pressure is 0.99 atm, the partial
pressure of carbon dioxide is 0.05 atm, and the partial pressure of hydrogen sulfide is 0.02 atm, what is the partial
pressure ofthe remaininB air?
O.a,a.&r.fn --
D.O541m
t
C.OZatnn
* ?,
Combined Gas Law
lr-10nS
Allows for
Formula
?,',ri-i-.
=
P.\J,
or
D,\, --rlr
,.V'
.T,
Example: A gas balloon has a volume of 106.0 liters when the temperature is 45.0 "C and the pressure is 740.0 mm Hg.
What will its volume be at 20.0'C and 780 .0 mm Hg pressure?
'i, = lo\-o.o'--f-, = +a + z+7 =3lBK
P,
-- ?40.0 rnnnl\g
ft*dro',)
3tx
s, =
\2 = 2b +znT' 293
7.
Pz '?8o'o cnm[3
@',,)
=TrLaLl
243
ldeal Gas Law
Combines all variables!
.-\,
Formura
Values for
P\ = nh
R:
O.OSZL
ges
t,
n= nno\eS
U@
8.31!(@
R=
62.4
cJrms<- corrzc+ K va\ue
L6;Td)
mol.K
mol.K
Example: How many moles of chlorine gas would occupy
temperature of
cor\slan+1= Irre\r/ in
a
volume of 35.5
L
at a pressure of 100.0 kPa and
\=355L
--rlt<
l,-;.t
P = lco vrPa
-t-=
(
IOO*
After determining the number of moles, calculate the number of grams of chlorine
l.4D\Af M ASS
i. 15 mo t Cl.
1.
=
Problems:
\
variattes
0\uCng
P , -- 99.o x?a
v, = o.3L
2.
llgctr
I I mor (,\.
-
is@j9
The volume of a gas at 99.0 tea
civen
molclz
zaZ=313Yr
= $'3\
Mixed Example
a
100. oC?
6Conve,(+
=
contained in this container?
Bt barcr.+6
L
lf the pressure is increased to 188 kPa, what will be the new volume?
. * PfzSS\,t(e
?. = tBB Oa.
\"
(Cl2)
(elofo a) = (tQlY\) =6 rssa
,6q- vdz
-
Z
A Bas sample at 40'C occupies a volume of 2.32
Gas Law
L. lf the temperature
is raised
to 75"C, what will the volume be,
assuming the pressure remains constant?
o.rrr* ChAf\A
T, = 40 +La3 = 3\b -f_--+3*z+3 -- Ag z.az I
Given va riables I
I
V,=Z'32L
3.
ar
\-=2.
\t
3qa
A gas in a sealed container has a pressure of 125 kPa at a temperature of 30.0"C. lf the pressure
is increased
crven
P.
*rr
inthecontainer
to 201 kPa, what is the new temperature?
variaoles? lSSL[(e
\25
t6
+
*-IZi fiP
P. = zol K?a
xQa
83-
u.rl.* Ga\- Lussarls
3ob
tz5
b5
zo\
-rz
=@\
4.
A helium-filled balloon at sea level has a volume of 2.1 L at 0.998 atm and 36'C. lf it is released and rises to an
elevation at which the pressure is 0.900 atm and the temperature is 28"C, what will be the new volume of the
balloon?
Given variables
'J,=2.
Gas Laur
lL
\)y='?.
'f
T, =3u +La7=)6fl
?
variables
, =2.$ +Z'1j=3Ol
u",
a
to.t\atm
= I .U8o.ttn
lf the pressure exerted by a gas at 25'C in
a
volume of 0.044
L is
Gas Law
'*T-
rden
(
:r\
= J.gr cr.*m
K = O.OBZI
to.BxD-'rnot
22.00 g of CO2 has a volume of 50.00
gas?
O@n{e-rl
L
and a pressure of 0.8210 atm. What must be the temperature of the
+o mo\
Given variables
Gas Law
zz.wgCO-,\ I moLQe = o.5o mo\
MDlo.f
--'
.44.otqC-O,
)
"
C-D,
"qr.r
ZZqL = lrnol
To convert moles of A
to llters of A:
You may need to convert groms
It,tffi2S
of gaseswill contain the same
nLuvs,rr" ZZ.Q
ar\4o (mur)t
-7-
To convert liters A to moles of A:
VD
-
egu50)*=Ei
(o.:of,o.oez)) 1--
h: O.SOmtl
R , o.o8zl
Avogadro's Principle
Atequal temperature and pressure,
ldea{
?. r). 9zlOaltrr
V=50L
N,-\oSS
Formura
- 5.s+=b-.a.l-
ro.ll
3.81 atm, how many molesofgas are present?
1)
u.
o
.
r.* DaLtOn-\
+ 3.89a+m' 1 p v
ri"btes]1tr16B*\,lg*$!-T= 75 +L13 = Z9O I(
V = o.oqq L
cir"n
7
_
Amixtureof three gases A, B, and C, is at a total pressure of 6.11 atm. The partial pressure of gasAis1.68atm;
that ofgas B is 3.89 atm. What is the partial pressure ofgas C?
Given
6.
M
P, 'O,qo+*
P, = og98a*m
5.
.eeB)(z.r)
i
*
or
At\)[fS
f On.latnS 'l rnbl
22.4'-
, \ rn0\
3rv<n(L)l lmol
. ZZ.q L
to
moles
or moles to
grams! gjVen (g) I rru\
I D\4( MasS (3)
gaS
atgg
sa{*p ?"^(t)]Wd-
1.
9r{cn ( L)
Problems:
Example
Whatisthevotumeof32molesofargonsar?
2.
'
3.
"
*
" ^;
':a'd
fi
4.
L __ +l(r.B L
, tnn+ft'
ZZ.r.{
*'i
ffi
!l"x:*=
=,]eY
Izi.qu 3mot
19!ea_;
I i"{il
ol CO.
i1i1
i
A sample of gas occupies 2.00
moles is increased to 10.0?
Se+
3Zpas+4.f1
L
with 5.00 moles present. What would happen to the volume if the num ber of
lCmot
!mot
up(}o-?(opo(hbn!
Ll
tno\es doutb\€. = rlu\tttn4
x
;--1
'.4L
dor,.bte5
What happened to the number of moles In a sample that originally occupied 500 mL with 2.50 moles and then
occupied 750 mL?
mot
poportron
2.5
*
o.b
CrOSS cru.Lfrp\rf
x
L
3.+er'-.,o\
o.aaL
:
Gas StoichiometrY
use fn gffif \ ent S i
2-aL, * ZHNor,.o, > -4 ltruo, +
-Hz
of hydrogen gas forms at STP, what volume of nitric acid was used?
Convert votume of A to votume of o,
1.
lf 45.60
L
43.UoL
2.
l-lzL
+t\u = q t.z L INO3
/ru*lz-
How many moles of hydrogen gas are made from 2.0
L
of nitric acid?
Z o L+tNos
ZZ,4
3.
LJlZ
\l
zz.4eHNo,\ I L +t
t
b3.oL3l-lNo3
4.
= o .o45
rnol
*12
5 g of nitric acid?
How many liters of hydrogen
lz.5qHl.lO"l
flust like using the mole ratio)
I mo
t
|l).l!3
z L +{NO3
- Z.1b L llz-
Balance the chemical equatlon and use it to solve for the following problems:
*NHrrgr *
a.
l_oao
)
+
-[H.o,r,
What volume of 02 8as is required to produce 34.0 Liters of NO?
34,ouNol 5LOzb.
iruo,
What volume of
Hu
= qLO.
O is produced from 2.0 moles of Oz?
z mol oz l zz.r-li-ozl g LtlzD _- 53.?t/ L
, lrnol oL 'aLoL
How ma ny grams of water are produced from 0.5
of oxygen gas?
fi"o
^ ,tr-t
^
o.6LO,-ito r-l.t/;\ \ mo\ A,O_)Lb_9!zO = u'1o1 4.o
lr^or-{-lro
@i
L