unit 4 gases and atmosphereic...
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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)