UNIT 5 GASES AND ATMOSPHEREIC CHEMISTRY

Chapter 11 – The Behaviour of Gases

States of Matter and the Kinetic Molecular Theory

Under normal conditions on Earth matter exists in 1 of 3 states:

i)

ii)

iii)

SOLIDS

When a substance is a solid, its particles (atoms, ions or molecules) are ________

_________________________________________________________________

The particles position in the lattice is relatively _______________. The particles

are unable to __________________________________.

The particles are not ________________________________________ (there are

spaces between all particles) but are bound by the _________________________

_________________________________________________________________

All particles are in ________________________________, in solids the particles

can only _____________________. This is called ________________________.

LIQUIDS

In liquids the particles are also bound, that is they _________________________

________________________________________________ (when one moves it

affects the movement of other particles or is restricted by them).

However particles in liquids can _______________________________________

_________________________________________________________________

In terms of motion, liquids move more freely. They can ____________________

___________________________. This is called _________________________.

The also ____________________________.

Because liquid particles move more around more they have a

__________________________________________________________________

Because solids and liquids are restricted in their movement, they are

____________________________________ and have ___________________________.

GASES

Particles in gases are able to move __________________________________.

They can move from _________________________________. This is called

______________________________________. Gases also have

_______________________________________________________________

Gas particles move with a ___________________________. They travel in

______________________ until they ________________ with other particles

and thus have a high _____________________________________.

Gas particles move ________________ than liquids and are

_______________________ by gravity. Gases flow in all directions. This

causes gases to _________________________________________________.

Gases can be _______________________ because of the large ____________

_______________________________________________________________

The particle theory states there is an ______________________________

between all particles. The ______________________ the force, the

___________________________the particles.

Gases –

Liquids –

Solids –

Forces between particles depend on:

1.

2.

Charged Particles

Charged particles (ions) are held together by ___________________________________.

+ve and –ve particles form _____________________. These attractions are

____________________. Therefore these compounds are ___________________.

Polar Molecules

Intermolecular forces exist between neutral particles and neutral and charge particles.

Some molecules are polar (asymmetrical shape), and have a

_________________________. This leads to dipole-dipole forces, which make most

polar substances __________________________________________.

Non-Polar

Non-polar molecules are held together by _____________________________________.

These forces are ____________________ and result in _____________l non-polar

substance being _______________ at room temperature.

As the size of non-polar molecules _____________________though, more dispersion

forces occur and the molecules are more ____________________________________,

resulting in substances that are ____________________________.

Temperature

Temperature is a measure of __________________________________________

__________________________________________________________________

The hotter a substance, the more ________________________ it has, the more

likely ___________________________________________________________

and thus become a gas.

Kinetic Molecular Theory of Gases

The following assumptions are made when working with gases:

1. Gas molecules have almost __________________________________________

so the spaces between them are huge. Therefore most of the _________________

2. There are neither ________________________________ between gas molecules.

3. Gas molecules have ______________________________, move _____________

and in _______________________.

4. When gas molecules collide the collisions are ____________________________

__________________________________________________________________

5. Average kinetic energy is ____________________________________________.

These assumptions allow us to understand the _________________________ because

nearly all gases __________________________________! This all leads to the idea of

an ______________________________ The term ideal gas is used to describe

________________________________________________________________________

Gas Pressure and Volume

When describing gases and pressure, we will usually be assuming a ________________

_____________________ (not open to the atmosphere), where the __________________

________________________________________________

PRESSUE is defined as ____________________________________________________

The SI unit for pressure is the _______________________________________________

Most often _________________________________________ are used for convenience.

For gases, pressure is determined using the ____________________________________.

Each collision between a gas molecule and its container __________________________.

The __________________________ as well as the ______________________________

result in _____________________________________________.

Since the atmosphere is composed of gases, the air ___________________________. A

column of air ______________ above you right now exerts a pressure of

______________________________. This is equivalent to about __________________!

Measuring atmospheric pressure has been done many ways

101.3 kPa is known as _____________________________________________________.

Relationship Between Pressure and Volume

When we refer to the volume of a gas, we are really taking about __________________

______________________________________________________________________

The definition of the volume of a gas is:

-

Perform Investigation 11-A on pg 430 to determine the relationship between P and V.

The experiment you did was first completed by the Irishman ______________________.

He used glass tubing and mercury to discover:

- the volume of a given amount of gas, at a constant temperature, ___________

_______________________________________________________________

- This is known as ____________________________________________

Boyle found this relationship was ________________________________________.

It works like this:

- as Pressure _____________________________________________________.

- As pressure , molecules ________________________. As volume , the gas

molecules __________________________ before _____________________,

which leads to _______________________________________ (more force)

which is an increase in __________________________________.

- Using the mathematical symbols:

- If the volume ____________________ – pressure is ___________________

- If the pressure ___________________ – volume is ____________________

We can get rid of the proportionality sign from above if we replace it with a constant.

What was the ____________________________________ on your graph? This is k for

your gas at a particular temperature.

So….

OR

k is a _________________________ so if you keep the _______________________ the

same, then __________________________for the initial conditions and

___________________________________for the final conditions OR:

Ex 1. If 8.25L of hydrogen is placed in a balloon at room temperature and standard

atmospheric pressure and is then submerged in a pool of water that is also room

temperature such that its pressure increases to 110.2 kPa, what is the final volume of the

balloon?

Ex 2. A 65mL sample of gas at 600 mm Hg is compressed to 4 atm. What is the new

volume of gas?

Gases and Temperature Changes

Recall that temperature is directly related to the kinetic energy of particles. ___________

________________________________________________________________________

Around the beginning of the 19th

century a French scientist name _____________

_____________ made a discovery that related ____________________________.

He found that all gases change their volume ______________________________

__________________________________________________________________

This worked for ______________ if _________________________ was constant

If you increase the temperature of a gas from __________________, its volume

_____________________________ _________________ of its original volume

If you decrease the temperature from ________________, its volume __________

__________________________________________________________________

Then came something REALLY BIG.

Based on his data, Charles reasoned that if you __________________ the

temperature of any gas _____________________ its volume would change by

___________________ its original volume.

THIS MEANS THE ________________________________________________!

Try Investigation 11-B on pg. 488 of your text.

Absolute Zero

Charles found no matter __________________________, every time he _____________

the lines on his graph, they all passed through ____________________.

The Scotsman _________________________ saw the significance in this. He reasoned

that at __________________ molecular motion __________________, kinetic energy

would ____________ and the volume of the gas _____________________________.

This lead to Kelvin developing the __________________________________.

Kelvin called __________________________________ and assigned it a value of ____.

From there, for every ____________________ the Kelvin scale increased ___________.

This scale works well because there are ______________________________.

Gas chemistry always works in degrees Kelvin

Charles’ Law

Charles’ Law states that ___________________________________________________

______________________________________________________________________.

Following the same logic as with Boyle’s Law we find that:

Ex 1. A balloon of He gas has a volume of 250cm3 and a temperature of 22.4

oC. If the

balloon is heated to 35.5oC, what will the volume of the He gas become?

Ex. 2. A 2L Pepsi bottle is filled with air at 21oC and placed in the freezer over night.

The next day the bottle is removed and has decreased in volume to 1.73L. What is the

temperature of the freezer?

Gay-Lussac’s Law

Most gases are stored in containers that are __________________________________.

So if the volume of a gas is really _________________________ (which cannot change),

then if the ____________________ of the gas changes the ________________________.

Joseph Louis Gay-Lussac discovered the relationship between _____________________

on a fixed volume of gas.

Gay-Lussac’s Law states:

________________________________________________________________________

_______________________________________________________________________.

Once again by introducing a constant, we can come up with:

Ex. 1. The fire extinguisher in your house may be designed to withstand 25 atm of

pressure. The pressure gauge on the extinguisher reads 1519.5 kPa at 22oC. If a fire in

your house heated the extinguisher to 95oC would the extinguisher explode?

Can you come up with a safety device that would stop any container from exploding

when heated?

Combined Gas Law Calculations

To solve many gas related problems __________________________________________.

Putting everything together results in the ______________________________________.

If looks like this:

Using this law you can calculate situations in which 3 variables change at the same time.

Ex. 1. At Mr. Dickson’s birthday party he tied balloons to his car. That particular day,

the weather changed as a warm low-pressure front moved in that had a temperature of –

4oC and a pressure of 100.7 kPa. The original temperature was –15oC and the pressure

was 103 kPa. What happened to the volume of the 3.9L balloons?

Ex. 2. A 10.0L sample of gas is collected at 175oC and 200 kPa. What pressure must be

applied to this gas sample to reduce its volume to 2.0L at 25oC?

Dalton’s Law of Partial Pressures

Often when dealing with gasses, you are dealing with ____________________________

like the air you breath. How is pressure affected ___________________________?

John Dalton asked this very question, and through experiments with air, found that the air

was ______________________________. He found that the amount of _____________

________________________________________. He found that by starting with dry air,

when ever he added water vapour the _________________________________________.

This led to __________________________________________________, which states:

________________________________________________________________________

________________________________________________________________________

Ex 1. A gas mixture of N2 and CO2 is at a pressure of 1.00 atm and a temperature of 5oC.

If 30% of the mixture is N2 what is the partial pressure of CO2?

Chapter 12 Exploring Gas Laws

The Ideal Gas Law

As Gay-Lussac worked with volumes of gases he discovered the following:

- When 1 Volume of gas was added to 2 Volumes of gas he ended up with

_______________________________________________

- __________________________________________________________

- __________________________________________________________

At the same time Dalton was studying the ____________________________________

in chemical reactions.

Based on each other’s observations they ______________________________________.

Law of Combining Volumes: (Gay-Lussac)

________________________________________________________________________

________________________________________________________________________

Law of Multiple Proportions: (Dalton)

________________________________________________________________________

________________________________________________________________________

These 2 ideas where combined by __________________________________________

He related the _______________ of a gas to the ________________________________.

Using ____________________________________ found that the

____________________ and the __________________________ of gases are the same!

This lead to _____________________________ HYPOTHESIS:

________________________________________________________________________

_______________________________________________________________________.

This in turn led to ______________________________________

What this means is that __________________________________ the same __________

_________________________________________ at the same temperature and pressure.

Before we move on there a couple of terms that need introductions:

MOLAR VOLUME – _____________________________________________________

STANDARD TEMPERATURE AND PRESSURE (STP)

This is defined as the average _______________________________________________

_______________________________________________________________________

STANDARD AMBIENT TEMPERATURE AND PRESSURE (SATP)

These are normal living conditions, defined as __________________________________

A 1.30L container has a mass of 4.73g. N2 gas is added to the container until a pressure

of 98.0 kPa at 22oC is reached. Together they have a mass of 6.18g. Calculate the molar

volume of N2 gas at STP.

Try the Molar Volume of Gases THOUGHT LAB on pg. 477.

From the Lab you should have discovered that ______________ (at the same T and P)

has ___________________________________.

At STP the _____________________________________________________________

Ex. 1. What is the volume of 5.4 mol of nitrogen dioxide at STP?

Ex 2. Suppose you have 35L of ammonia gas at STP.

a. How many moles are present?

b. What is the mass (in g) of the gas?

c. How many molecules of gas are present?

Real vs. Ideal Gases

Ideal gases have a V = 22.4L at STP. The volumes of real gases are _______________

___________________________________________. At _______________________

____________________________________________, gases ____________________

ideally. _______________________________ become more important as gas particles

get ______________________.

There is an easier way

By combining the _______________________ with ______________________ we can

make gas problems easier to solve.

Here we go!

The Combined Gas Law says V T/P and Avogadro’s Law says V n so….

Because all gases behave alike, we can find R for 1 mole of gas at STP.

R is called the _________________________________________________________

Putting this all together we get the _________________________________________

When using the Ideal Gas Law always:

1. Convert _______________________________________________

2. Convert _______________________________________________

3. Convert _______________________________________________

4. Convert _______________________________________________

Ex. 1 Find the molar volume of a gas at SATP.

Ex. 2. 6.00L of CO2 in a container holds 2.17 mol at 300 kPa. What is the temperature in

the container.

Ex. 3. Calculate the volume of 8.00g of He gas at a pressure of 500 torr and a

temperature of –120oC.

Ex 4. Laughing gas is stored in cylinders that are 140cm high with a 23cm diameter. The

pressure of the gas is 50 kPa and its temperature is 21oC. How many grams of N2O are in

the cylinder?

Applications of the Ideal Gas Law

Your lungs hold air, and work based on _________________________. When you

breathe in your ___________________________ and your

________________________. This expands the ______________________of your

chest. Boyle’s Law says that the ______________________ in your chest should

___________________. This results in _____________________________ inside your

body, compared to outside, and

________________________________________________________________. When

you breathe out the opposite is true. Your chest _______________________________

and therefore ____________________________________________ of the gas inside.

How many molecules of O2 can you fit into your lungs at one time?

To find molecules of O2 we need:

To find Volume we will measure your lung capacity:

Tidal Volume:

Inspiratory reserve volume:

Expiratory reserve volume:

Vital capacity:

Residual volume:

Total lung Capacity:

Density of Gases

Density of a gas is similar to the density of a solid or liquid.

Units for density of a gas are _________________

Ex. 1 Find the density of N2 gas in g/L at 21oC and 104kPa.

Molar Mass of Gases

You can find the molar mass ______________ of a _____________________ or

compound the same way you have for any other element or compound.

Ex. 1. You have a 3.283g of a gas you think is an element from the noble gases. The

sample occupies 500ml at 45oC and 132.2kPa. What is the molar mass of the gas and

what noble gas is it?

Ex. 2. The year is 3030 and an archaeologist comes across an ancient village. While

digging he punctures a container and a gas leaks out. Upon analysis, the gas is found to

contain 81.68% carbon and 18.32% hydrogen. He also finds that a 4.13g sample takes up

1.25L at 1520mm Hg and 52oC. What is the molecular formula for the gas?

Gas Law Stoichiometry

Many chemical reactions involve gases. If the ___________________ are gases and you

need to know the number of _____________ involved you will use the ______________.

If ________ the reactants and the products are ___________ than you can use _________

___________________________________________ with mole ratios to solve problems.

To solve gas stoichiometry problems:

1.

2.

3.

4.

5.

Ex. 1. Combining oxygen gas and hydrogen gas produces water vapour. Suppose that

15.0L of oxygen gas reacts with hydrogen gas at STP. What volume of water vapour is

produced and what volume of hydrogen is consumed?

Ex. 2. Iron reacts with sulfuric acid to produce a gas. What volume of gas is produced

with excess sulfuric acid reacts with 22.0g of iron at 23oC and 99.6kPa?

Water Vapour Pressure during experiments

Many gases are ______________________________________________ by allowing

them to ___________________________. The problem is that ________________

molecules __________ with the gas sample. To account for this you must ___________

_______________________________________________________________________.

A student reacts zinc metal with excess dilute hydrochloric acid and produces H2 gas.

They used 0.255g of metal. What volume of “dry” H2 gas do they collect over water at

22oC and 101.1kPa?

(You will need to look up the partial pressure of water vapour in table 12.3 on pg. 507)

Gases as Reactants

You can also solve problems when gas is a reactant.

Ex. 1. Oxygen reacts with iron to produce 172g of iron (III) oxide, at 102.4kPa and 26oC.

How many litres of oxygen are consumed?

Make sure you do your “hitlist” questions for chapter 12!!!