View by Category

Loading...

PPT – Gases Lecture III PowerPoint presentation | free to download - id: 80bf5f-NGE5M

The Adobe Flash plugin is needed to view this content

About This Presentation

Write a Comment

User Comments (0)

Transcript and Presenter's Notes

Gases Lecture III

- The Ideal Gas Law and Daltons Law of Partial

Pressures

The Ideal Gas Law

Is there a relationship between the following

variables?

pressure

volume

YES

number of moles

temperature

they all have an affect on one another

the ideal gas law allows us to quantify this

relationship by providing us an equation to

evaluate the effects of one variable on another

In equation form, the ideal gas law looks like

this

PVnRT

P is pressure in atmospheres

V is volume in liters

n is the number of moles of all gases present

T is the temperature in Kelvin

R is the ideal gas constant

- R 0.0821 atm x L/mol x K

Heres a problem using this equation

What pressure, in atmospheres, is exerted by

0.450 mol of nitrogen gas in a 6.10 L container

at standard temperature?

1. Identify the variables

n0.450 mol V6.10 L T273 K R 0.0821 atm x

L/mol x K

2. Rearrange the equation

PVnRT

PnRT/V

3. Solve the problem

P(0.450 mol)(0.0821)(273 K)/(6.10 L)

P1.65 atm

My lungs hold 6.30 L of air at normal body

temperature (37 oC) and standard pressure.

Assuming that air is made up of 20.9 oxygen, how

many oxygen molecules are in my lungs after I

take a breath?

1. Identify the variables

V6.30 L T310 K P1.00 atm R0.0821 atm x L/mol

x K

2. Solve the equation

PVnRT

nPV/RT

3. Solve the equation

n(1.00 atm)(6.30 L)/(0.0821 atm x L/mol x K)(310

K)

n0.2475 mol

4. Apply the percentage

- n is the number of molecules of any gas, so each

gas contributes the same to the total volume and

pressure, regardless of molar mass

moles of oxygen0.2475 mol x 20.9

moles of oxygen0.05173 mol

5. Convert to molecules

0.05173 mol

X

6.022 x 1023 molecules

1 mol

3.12 x 1022 molecules

Daltons Law of Partial Pressures

- partial pressure is defined as the pressure of

each individual gas in a mixture

- remember ideal gases all behave the same way

- Daltons law of partial pressures states that the

total pressure of a mixture of gases is equal to

the sum of the partial pressures of the gases in

the mixture

In an equation, it looks like this. . .

PtotalP1P2P3. . .

barometer

Poxygen0.12 atm

bulb with gas

Pnitrogen0.12 atm

Ptotal0.24 atm

What does the pressure of a gas depend on?

Primarily the number of moles of gas present

The greater the number of moles of a particular

gas present in a sample, the greater that gas

contributes to the total pressure of the sample

- if a gas makes up 3/5 of a sample, it accounts

for 3/5 of the total pressure - if a gas makes up 64 of a sample, it accounts

for 64 of the total pressure

the percentages and fractions refer to the number

of moles, not the mass

IMPORTANT

lets try an example

A 4.8 g sample of gas containing only nitrogen

and oxygen contains 3.1 g of O2. The gas is

sealed in a container and exerts a pressure of

940 mm Hg. What is the partial pressure of each

gas in the container?

1. Find the number of moles of each gas

molmass(g)/molar mass

mol O2(3.1 g)/(32.00g/mol)

0.09688 mol O2

mol N2(1.7 g)/(28.02g/mol)

0.06067 mol N2

2. Determine the mole fraction of each gas

mole fractionmoles of individual gas

total moles of gas

total moles of gas 0.09688 mol O2 0.06067 mol N2

0.15755 mol

mole fraction O20.09688 mol/0.15755 mol

0.6149

mole fraction N20.06067 mol/0.15755 mol

0.3851

3. Multiply total pressure by the mole fraction

to determine partial pressure of each gas

Poxygen940 mm Hg x 0.6149

578 mm Hg

Pnitrogen940 mm Hg x 0.3851

362 mm Hg

check 578 mm Hg 362 mm Hg 940 mm Hg

- When chemists want to collect a gas, they often

do it with a technique known as water

displacement - the reaction you are about to see makes hydrogen

gas

H2O is present due to slight evaporation

reaction vessel

What factor could increase the amount of

evaporated H2O?

temperature

the greater the temperature, the greater the

number of water molecules present above the water

What will this do to the partial pressure of H2O?

Increased temperature will increase the partial

pressure of H2O

this can be observed in chart 8 in the appendix

of your book

The gas inside the water displacement chamber is

at equilibrium with the gas outside the chamber

in other words, the gas inside is at the same

pressure as the gas outside (Patm)

the atmospheric pressure is the same as the total

pressure inside the chamber

PatmPgasPwater

Helium gas is collected over water at 25 oC.

What is the partial pressure of the helium if the

atmospheric pressure outside the water collection

bottle is 765 mm Hg?

1. Find the pressure of water at that temperature

2. Rearrange the equation

PatmPgasPwater

PgasPatm-Pwater

3. Solve the equation

Pgas765 mm Hg 23.8 mm Hg

741.2 mm Hg

About PowerShow.com

PowerShow.com is a leading presentation/slideshow sharing website. Whether your application is business, how-to, education, medicine, school, church, sales, marketing, online training or just for fun, PowerShow.com is a great resource. And, best of all, most of its cool features are free and easy to use.

You can use PowerShow.com to find and download example online PowerPoint ppt presentations on just about any topic you can imagine so you can learn how to improve your own slides and presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

You can use PowerShow.com to find and download example online PowerPoint ppt presentations on just about any topic you can imagine so you can learn how to improve your own slides and presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

presentations for free. Or use it to find and download high-quality how-to PowerPoint ppt presentations with illustrated or animated slides that will teach you how to do something new, also for free. Or use it to upload your own PowerPoint slides so you can share them with your teachers, class, students, bosses, employees, customers, potential investors or the world. Or use it to create really cool photo slideshows - with 2D and 3D transitions, animation, and your choice of music - that you can share with your Facebook friends or Google+ circles. That's all free as well!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

For a small fee you can get the industry's best online privacy or publicly promote your presentations and slide shows with top rankings. But aside from that it's free. We'll even convert your presentations and slide shows into the universal Flash format with all their original multimedia glory, including animation, 2D and 3D transition effects, embedded music or other audio, or even video embedded in slides. All for free. Most of the presentations and slideshows on PowerShow.com are free to view, many are even free to download. (You can choose whether to allow people to download your original PowerPoint presentations and photo slideshows for a fee or free or not at all.) Check out PowerShow.com today - for FREE. There is truly something for everyone!

Recommended

«

/ »

Page of

«

/ »

Promoted Presentations

Related Presentations

Page of

Home About Us Terms and Conditions Privacy Policy Contact Us Send Us Feedback

Copyright 2017 CrystalGraphics, Inc. — All rights Reserved. PowerShow.com is a trademark of CrystalGraphics, Inc.

Copyright 2017 CrystalGraphics, Inc. — All rights Reserved. PowerShow.com is a trademark of CrystalGraphics, Inc.

The PowerPoint PPT presentation: "Gases Lecture III" is the property of its rightful owner.

Do you have PowerPoint slides to share? If so, share your PPT presentation slides online with PowerShow.com. It's FREE!