A 482 moles of N 2 B 553 moles of N 2 C 602 moles of N 2 D 964 moles of N 2 Dalton s Law of Partial Pressure Continued So what if we said n total n 1 n 2 n ID: 932347
Download Presentation The PPT/PDF document "Warm-Up 12/14/2016 How many moles of nit..." is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Warm-Up 12/14/2016
How many moles of nitrogen are in 135 L of nitrogen gas at Standard Temperature and Pressure(STP)?
A) 4.82 moles of N
2
B
)
5.53 moles of N
2
C) 6.02 moles of N
2
D) 9.64 moles of N
2
Slide2Dalton’
s Law of Partial Pressure Continued
So what if we said:
n
total
= n
1
+ n
2
+ n
3
+ ….
If each of the gases obeys the ideal gas equation, we can write :
P
1
= n
1
(RT/V) , P
2
=n
2
(RT/V), P
3
= n
3
(RT/V)
P
total
= ( n
1
+ n
2
+ n
3
+ ….) (RT/V) =
n
total
(RT/V)
Slide3Practice
A gaseous mixture made from 6.00 g O
2
and 9.00 g CH
4
is placed in a 15.0 L vessel at 0˚ C. What is the partial pressure of each gas, and what is the total pressure in the vessel
Slide4Practice
What is the total pressure exerted by a mixture of 2.00 grams of H
2
and 8.00 grams of N
2
at 273 K in a 10.0 L vessel?
Slide5Collection of Gas by
Water Displacement
Gases are often collected
by bubbling
them through water
This is known as
“
collecting a gas by water displacement
”
The total pressure is equal to the gas
’
s pressure plus the pressure of the water vapor
P
total
=
P
gas
+
P
water
vapor(H2O)
Slide6Slide7Example Problem
A quantity of gas is collected over water at 8°C in a 353 cm
3
vessel. The manometer indicates a pressure of 84.5
kPa
. What is the pressure of the gas if the vapor pressure of water at 8°C is 1.1
kPa
?
Slide8Example # 2
A 450 cm
3
sample of hydrogen is collect over water at 12
o
C. The pressure of the hydrogen and water vapor mixture is 78.5
kPa
. What is the partial pressure of the dry hydrogen gas? Water vapor pressure at 12 ° C is 10.52
kPa
Slide9Graham
’
s Law
Diffusion
is the random scattering of gas molecules
It is the
mixing
of gas molecules
Diffusion occurs when molecules migrate from areas of
high concentration
to areas of
low concentration
Example: If a bottle of ammonia is open, you will soon smell the ammonia due to the diffusion of gaseous ammonia particles
Slide10Graham
’
s Law Continued
Graham determined a law that
allows for the rate
of effusion to be measured
Effusion
occurs when gas molecules escape from a small hole in the gas
’
s container
Graham found that the rate of effusion of a gas is
inversely proportional to the square root of its molar mass
Slide11Diffusion and Effusion
Slide12Graham
’
s Law Continued
The
larger
a particle
’
s mass,
the slower
the particle will
effuse
Graham
’
s Law is:
Rate B
molar mass
gas A
Rate A
molar mass
gas B
=
Slide13Example #1
What is the relative rate of diffusion of Helium to Neon?
Ans) 2.24
Interpretation: Helium particles will diffuse 2.24 times faster than Neon particles
Slide14Additional Examples
3.
Compute the relative rate of diffusion of argon to radon
4. Compute the relative rate of diffusion of helium to argon
Ans 3) 2.36
Ans 4) 3.16
Slide15Practice
A sealed can with an internal pressure of 721
Torr
at 25 ˚C is thrown into an incinerator operating at 755˚C. What will be the pressure inside the heated can, assuming that container remains intact during incineration?
Slide16Practice
How many molecules are in a gas that has a pressure of 6
kPa
, a volume of 5 L, and a temperature of 127°C?
Slide17Practice
What is the volume of 1.00 mole of a gas at
stadard
temperature and pressure?
Slide18Practice
A 113 L sample of helium at 27˚C is cooled at constant to -78.0˚C. Calculate the new volume of the helium.
Slide19Practice
What volume of He is occupied by 2.35
mol
of He at 25˚C and a pressure of 0.980
atm
?