r
20. Helium filled balloons rise in the air because the density of helium is less than the density of
air.
(a). If air has an average molar mass of29.0 g/mol, what is the density of air at 25.0oC and 755
mmHg?
(l'l1.oU\1L ~ss)
f
d:
= 1<--1_, 1_8 _-1'L_l
~T
(b). What is the density of helium at the same temperature and pressure?
(I..{. 00) (
.J
OL
::
l_ 0,
z:
(.o8J.,)(c29G)
Jl
g,
j
75~('D)
I~ J
~
-
(c). Would a balloon filled with carbon dioxide at the same temperature and pressure rise?
d.
755
('1'1.01) (
z:
)
-( • 0 ~;1/ ) ( ,;z
(l.?q
=
M.
t; f)
.J1t.]
!.f()
-
21. Phosgene is a highly toxic gas made up of carbon, oxygen, and chlorine atoms. Its density at
1.05 atm and 2S.0oC is 4.24 g/L.
(a). What is the molar mass ofphosgene?
d ILT
('I.,) Cf)
-p
=
(. Of.).') ( r>2?J)
I, fJ..J
(b). Phosgene is made up of 12.1% C, 16.2% 0, and 71.7% Cl. What is the molecular formula of
phosgene?
c
0
(~
t
coa,
I
iMI =
/.0/
kn-\PI.Q.ICAL
I~. ~
11,,00
0
~ 1.01
0
--
MASS
Fdbt1vLA
c= ((I~.OI) =- loJ. I
o I (1",00) ;: 1(,. 00
CJ -- ~ (3S.
'70 • f'D
0
z:
t.f ~)
CJ
71.7
35.(j~
;:
~.O ~
CI
0
z
;:
qe.CfI
a
MOLECUlAtt
FOR~()(A
( cae}, 1
-.

10th Sci. Kan -2014;pdf

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