effusion and real gases. announcements: tutor review session from 5-7 tonight in dbh 1100 added...

Effusion and Real Gases

•Announcements:• Tutor Review Session from 5-7 tonight in DBH 1100

• Added additional gas law questions to “sample exam” questions. Posted on website

• Studying for the final

• video questions (level 1), in class worksheets (level 1-3), mastering homework (level 1-5), sample midterm questions(level 1-5), sample final questions(level 1-5)

• Office hours next week. (see calendar)

• Mine RH 214: Monday 10-11:30, Monday 2-3:00, Tuesday 3-4

• Pauls 3rd floor NSI : Tuesday 12-1

• Survey question comment: if you are still having problems with geometry, hybridization, chapter 5, 8 ect…. Please please come see me in office hours, we don’t have enough class time to go back and do this but Paul and I can help you in office hours!

Remember back 5 rows of even side

are no seating zones

Visit: https://checkin.ics.uci.edu/ Word of the day: doneLearningCatalytics: session ID:62286353

https://checkin.ics.uci.edu/

SURVEY QUESTIONS.

• Choosing R:• Things involving energy, 8.314 or Things involving volume and pressure

0.0821

• Don’t bother with the other 15 or so versions, just stick with these two and convert other units to match.

• How do you know which number to plug in for R1 and R2, and M1 and M2 (and my addition to this: what about T1 and T2?)• Make sure they match and it doesn’t matter! If it helps you can label

them a/b instead of 1/2

• Light molecule= fast rate= short time

• Heavy molecule= slow rate= long time

• Ratio a to b of 1.2: a=1.2, b=1



SURVEY QUESTIONS.

• Do we get gas conversions on the exam? Do we get a and b for the Van der Waals equation on the exam? • Of course, you know I wouldn’t make you memorize such things.

• Whats your favorite color on the electromagnetic spectrum. • Around 510-515nm ish.

• Survey question comment: if you are still having problems with geometry, hybridization, chapter 5, 8 ect…. Please please come see me in office hours, we don’t have enough class time to go back and do this but Paul and I can help you in office hours!



Review: Kinetic Molecular Theory of Gases

Which of the following is true?

• The average speed of gas molecules decreases with decreasing temperature.

• The kinetic energy of a molecule cannot determine its speed.

• There are gas molecules that move slower than the average.

• All the gas molecules in a sample cannot have the same kinetic energy.

• The average kinetic energy of gas molecules decreases with decreasing temperature. Visit: https://checkin.ics.uci.edu/

Word of the day: doneLearningCatalytics: session ID:62286353


Effusion: Process of escaping through tiny holes, (often into an empty container, although not always).

Diffusion: Movement of molecules (typically in liquid or gas) from area of high to low concentration through larger openings. For each circumstance say if the gas is effusing, diffusing or neither:

Picture A)

Picture B)

Movement of helium particles through a balloon causing it to deflate over time.

Movement of helium particles into the air when the mouth of a balloon is opened.

Enriching isotopes by using the difference in rms speeds to separate different mass molecules.

Perfume molecules spread from a spay on one side of the room to the other.

A)

B)

Diffusion

Effusion

Effusion

Effusion

Diffusion

Diffusion



For an Oxygen and Bromine gas mixture which molecules have the larger:

• Mass?

• Greatest average velocity?

• Rate of effusion?

• Partial Pressure?

Bromine

Oxygen

Same

Oxygen



CONCEPT: KINETIC MOLECULAR THEORY EFFUSION:

• Without doing any calculations, put the following in order of increasing rate of effusion and time of effusion. Molecular masses are in parenthesis.

• Ne (20.18 g/mol), C3H8 (44.11), He (4.00) and NO2 (46.01)high mass equals slow (aka low rate, long time): low mass equals fast (aka high rate, short time)

Rate:NO2, C3H8, Ne, He

Time:He , Ne, C3H8, NO2



CALCULATIONS: KINETIC MOLECULAR THEORY

• What is the molar mass of a compound that takes 2.7 times as long to

effuse through a porous plug as it did for the same amount of XeF2 at

the same temperature and pressure?

Hint:



Real vs. Ideal Gas

• Under what types of pressure do gases behave ideally?

• Under what type of temperatures do gases behave ideally?

• We originally defined ideal gases with as series of requirements. These included, no volume, elastic collisions, and they do not interact. Match these requirements with the conditions above.

• We haven’t learned about how to tell if molecules interact with each other yet (it is in 1B), however, would a molecule that strongly interacts with other molecules be more or less ideal?

Low pressure

High temperatures

No volume: Low pressure means volume of atoms are a lower percent of the total volume.

No interactions: High temperatures mean molecules are moving quickly and lots of kinetic energy, interact less.

Less ideal.

Talking about together



REAL GAS EXAMPLE (we may not have time for this one the

real gas material, depending on the speed of the class we may finish this up on

Friday.)

• Calculate the pressure exerted by 1.00 mol of C2H6 behaving

as an ideal gas and a Van der Waals gas when it is at 1) 273.15K in 22.414L and also 2) at 1000. K in 0.100L. Think about what these answers tell you.

Ideal Gas Law

Van Der Waals Gas

Rearranged for P

Conditions 1a=4.562b=0.0638





Friday.)

• Calculate the pressure exerted by 1.00 mol of C2H6

behaving as an ideal gas and a Van der Waals gas when it is at 1) 273.15 in 22.414L and also 2) at 1000. K in 0.100L. Think about what these answers tell you.

Rearranged for P

Ideal Gas Law

Van Der Waals Gas

Conditions 2Visit: https://checkin.ics.uci.edu/

Word of the day: doneLearningCatalytics: session ID:62286353




Friday.)

• Calculate the pressure exerted by 1.00 mol of C2H6

behaving as an ideal gas and a Van der Waals gas when it is at 1) 273.15 in 22.414L and also 2) at 1000. K in 0.100L. Think about what these answers tell you.

Ideal Gas Law

Van Der Waals Gas

Summary

Difference 0.006atm 989atm

Condition 1Atmospheric like

Condition 2High Pressure

At atmospheric pressures gases act ideally. At high pressures they do not. (Note: high temperatures in general actually make a gas act more ideally if still at a low

pressure, however if the high temperatures increase the pressure then the change in pressure causes gases to act non-ideally.)



effusion and real gases. announcements: tutor review session from 5-7 tonight in dbh 1100 added...

Documents

average speed of gas

session id

movement of molecules

gas conversions

office hours

survey questions

perfume molecules

additional gas law questions