Week 4 Gases

Question 1

Partial Pressures Definition and Dalton’s Law of Partial Pressures

Answer 1

Partial pressure=Pressure exerted by a single gas component of a mixture if it was on its own
Dalton’s Law od Partial Pressures: The total pressure of a multi component gas mixture is the sum of partial pressure of each component

Question 2

What is the equation for the partiaol pressure of each gas component?
What is the total pressure in terms of the total number of moles
(Use a,b,c)

Answer 2

PA=na(RT/V), PB=nb(RT/V), PC=nc(RT/V)
Ptotal= (na+nb+nc)(RT/V)

Question 3

How do you calculate the mole fraction?

Answer 3

Pa/Ptotal=Xa= na/ntotal

Question 4

How do you find the component of a gas (n) in a gaseous mixtture

Answer 4

Pn=Xn(Ptotal)

Question 5

What is root mean square used to determine, what is the equation

Answer 5

To describe the average particle motion of a single particle in gas samples
urms=((3RT)/(NAm)^1/2 aka sq root
Na=Avogadros number times mass=Molar mass
therefor you can use Molar mass for the denominator

Question 6

In the root mean square equation, what should molar mass be calculated in? What is R? Does chemical identity matter? Why do you square root

Answer 6

R=8.314 J/mol x K
Molar mass in kg/mol
Chemical identity matters
To get the units in m/s instead of m2/s2

Question 7

What is the result of particle mass and temperature on avaerage velocities

Answer 7

Lighter and higher temp results in higher average VELO

Question 8

What is the mean free path, what is the equation λ

Answer 8

What is the mean free path λ is the average distance between collisions
λ=(distance travelled)/number of collisions
It is inversely proportional to pressure (1/P)

Question 9

Diffusion/Effusion/Grahams Law of Effusion/Diffusion

Answer 9

Diffusion: Process by which the particles spread out down a concentration gradient
Effusion: Process of particles escaping into a vaccuum through a pinhole
graham: Rate is inversely proportional to the square root of the molar mass (1/M^1/2)

Question 10

What is the ratio of Effusion Rates

Answer 10

ratea/rate b= square root of Mb/Ma (MOLAR MASS)

Question 11

Real gases have:

Answer 11

Intermolecules forces between atoms and molecules (attractive and repulsive forces)
Atoms and molecules have finite volume albeit small

Question 12

What is the Particle Volume Corrected Gas Law and Why

Answer 12

P(v-nb)=nRT
Real gases have a fomote particle volume (greater than 0) whereas ideal has negligible volume (0)

Question 13

When are corections significant for finite particle volume?

Answer 13

Same number of particles and temperature and at HIGH PRESSURE

Question 14

Note:
At a given temperature
and pressure, volume
of gas also depends on
repulsion or attraction
dominant IMF between
atoms/molecules.

Question 15

What is an example of a negative adjusment to ideal gas Pressure (P)

Answer 15

P=nRT/V-a(n/V)^2
SO
P+a(n/V)^2=nrt/V

Question 16

What happens to the correction factor as molar volume decreases

Answer 16

Correction factor becomes more negative

Question 17

What is corrected pressure/volume

Answer 17

Volume: V-nb
Pressure: P+ a(n/V)^2

Question 18

What is the Van Der Waals equation and what does it correct for?

Answer 18

(P+a(n/V)^2)(V-nb)=nRT
Corrected IMF for first part
2nd part for volume