Technical Science Introduction to Chemistry

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Technical ScienceIntroduction to Chemistry

• States of Matter

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States of Matter

• In this section you will
• Describe the Three States of Matter
• Describe the Factors Affecting Gases
• Relate Temperature, Volume, and Pressure.
• Use the Gas Laws to Solve Problems

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Describe the Three States of Matter
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Home

• If you were to classify the substances in this
  room, how would you do it?

• One method of classification would be to separate
  the substances by state.
• All the substances in this room could be grouped
  into solids, liquids, or gases.

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Describe the Three States of Matter
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• The substances in this room are either solid,
  liquid, or gas.

• What determines the state of a substance?
• The state of any substance can be changed by
  adding or removing heat.

Solid
Liquid
Gas
Solid
Gas
Liquid
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Describe the Three States of Matter
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• There is some important terminology associated
  with changing states.

Gas
Boiling Point
The process of changing from solid to gas is
called Sublimation.The process of changing from
gas to solid is Deposition
The temperature at which a liquid turns into a
gas is called the Boiling Point
The process of changing from solid to liquid is
called Melting.The process of changing from
liquid to solid is Freezing
The temperature at which a solid turns into a
liquid is called the Melting Point
The process of changing from liquid to gas is
called Vaporization.The process of changing
from gas to liquid is Condensation
Liquid
Solid
Melting Point
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Describe the Three States of Matter
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• Match the terminology from the previous slide to
  define water in the situations described below.

• - Water vapor forms droplets on a cold can of
  soda.
• - 100 Celsius - 212 Fahrenheit
• - A pile of snow disappears although the
  temperature is below freezing.
• - The ice cubes in your soda disappear
• 0 Celsius - 32 Fahrenheit
• The surface of the lake solidifies
• The sun evaporates water from a lake

Melting Freezing Condensation Vaporization Sublima
tion Freezing Point Boiling Point
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Describe the Three States of Matter

• What happens to the particles in a substance when
  the state is changed?

• Remember, to change the state of any substance
  you add or remove heat.

Solid
Liquid
Gas
Solid
Gas
Liquid
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Describe the Three States of Matter

• When a solid is heated, the particles gain energy
  and move faster.

• They move further away from each other so the
  substance becomes less dense.
• The forces that hold one particle to another are
  overcome and the particles are free to slide past
  each other. The solid loses its rigidity and
  melts.

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Describe the Three States of Matter

• When a liquid is heated, the particles gain more
  energy and move even faster.

• They move further away from each other so the
  substance becomes even less dense.
• The forces that hold one particle to another are
  completely overcome. They jump from the liquid
  to the gas state and vaporize.

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Describe the Three States of Matter

• As a substance cools the reverse happens.

• The gas particles lose heat, slow down, become
  more dense, and condense into a liquid.

• As the liquid is cooled, the particles continue
  to slow. They move closer together becoming more
  dense which allows for more attraction between
  particles and they solidify.

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Describe the Three States of Matter

• A substance changes state because of the addition
  or removal of heat.

• But the substance itself is not changed when its
  state is changed.
• For example ice, water, and steam are all
  composed of water (H2O) particles. The only
  difference is the amount of heat energy.

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Describe the Three States of Matter
Solids

• In a solid, the particles are locked into
  specific arrangements making them rigid.

• Solids maintain a specific shape and volume
  because there is an attraction between particles.

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Describe the Three States of Matter
Solids

• Since solids maintain a specific shape and
  volume, the container you put them in wont
  matter.

• The solid retained its shape and volume,
  regardless of the container.

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Describe the Three States of Matter
Solids

• We rely heavily on these properties of solids.

• When we build a car or a building or a bridge, we
  want to make sure that it retains its shape and
  wont shrink or expand.

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Describe the Three States of Matter
Liquids

• In a liquid, there is some attraction between
  particles but they are not locked into a
  specific arrangement.
• The particles in a liquid are free to slide past
  one another making them fluid.

• Because liquids are fluid, they have no definite
  shape but their volume remains constant.

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Describe the Three States of Matter
Liquids

• Since liquids are fluid, they will change shape
  to fit their container.

• The liquid changed shape but the volume remained
  constant.

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Describe the Three States of Matter
Liquids

• Hydraulic systems rely on the ability of fluids
  to change shape but retain a constant volume.

• Since a liquid can change shape, it can be pushed
  through pipes, cylinders, and hoses.
• Since the volume of a liquid doesnt change
  (liquid cant be compressed), force can be moved
  from one area to another through liquid in a hose.

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Describe the Three States of Matter
Gases

• In a gas, there is little or no attraction
  between particles because they are relatively far
  apart.
• The particles in a gas are also moving rapidly in
  every direction because they have a lot of energy.

• Because of their high energy and low density,
  gases have no definite shape or volume.

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Describe the Three States of Matter
Gases

• Gases are also fluid, they will change shape to
  fit their container.

• The gas changed shape but it also expanded to
  fill the entire container so its volume changed
  as well.

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Describe the Three States of Matter
Home
Gases

• Solids have constant shape and volumeLiquids
  have constant volume but variable shape.Gases
  have variable shape and volume
• This means gases can be expanded or compressed
  and they can take on the shape of any container
• Because gases are so variable they are affected
  to a great extent by environmental factors like
  Temperature, Volume, and Pressure.
• We will discuss these factors and their affect on
  the behavior of a gas in the following section.

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Describe the Factors Affecting Gases
Home

• We will discuss Temperature, Volume, and Pressure
  and their relationship to the behavior of gases.

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Describe the Factors Affecting Gases
Temperature

• Temperature is a measure of the amount of heat in
  a substance.
• As you heat up a gas the particles move faster
  and further away from each other.

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Describe the Factors Affecting Gases
Volume

• Volume is a measure of the space that a gas
  occupies.
• A given number of gas particles will expand or
  compress to evenly distribute themselves through
  a given volume.

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Describe the Factors Affecting Gases
Pressure

• Pressure is a multidimensional property composed
  of the basic units of force and area.

Force
Pressure
Area

• Pressure is measured in units such as

Pounds
Newtons
Square Inch
Square Meter
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Describe the Factors Affecting Gases
Pressure

• In what situations have you heard the term
  pressure?

• You have had your blood pressure taken when you
  go to the doctor. This is a measure of the force
  with which your blood pushes on the walls of your
  vessels.
• At some point, you have probably measured the air
  pressure in a car or bike tire. A pressure of
  36 lb/in2 means the air is pushing on every
  square inch of tire with a force of 36 pounds.
  

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Describe the Factors Affecting Gases
Pressure

• Your body is currently under pressure from the
  weight of the atmosphere pushing on you.

• Standard atmospheric pressure is 14.7 lb / in2.
• This means that the air around you is pushing on
  every square inch of your body with 14.7 lb of
  force.

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Describe the Factors Affecting Gases
Pressure

• There are a number of different units that may be
  used to measure atmospheric pressure.

Standard Atmospheric Pressure
29.92 in. Hg
760 mm Hg
760 torr
1 atmosphere

• The different units are the result of using
  different measuring instruments.
• If you listen to the weather forecast you also
  know that atmospheric pressure can change. This
  is based, in part, on temperature and elevation.

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Describe the Factors Affecting Gases
Pressure

• You are able to withstand the atmospheric
  pressure because your body evolved to handle it.

• Our bodies are pushing back against the
  atmosphere with an equal 14.7 lb/in2 of pressure.

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Describe the Factors Affecting Gases
Pressure

• What would happen to your body if you were sent
  into space where there is no atmosphere?

• If there is no atmosphere then there is no
  external pressure but our bodies would continue
  to push out at 14.7 lb/in2. With nothing pushing
  back against us our bodies would explode.

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Describe the Factors Affecting Gases
Home
Pressure

• If you pump up a bike tire to 65 lb/in2, What are
  the air particles doing that keeps the tire
  inflated?

• Gas particles are constantly moving in every
  direction. As they collide with the inner walls
  of the tire they exert a force on the inside of
  tire. The sum of the forces of all those
  collisions is what accounts for the pressure that
  keeps the tire inflated.

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Relate Temperature, Volume, and Pressure
Home

• In this section, you will explore the
  relationship between Temperature, Volume, and
  Pressure

• In other words if we change one factor, what
  will happen to the other?

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Relate Temperature, Volume, and Pressure
Temperature and Volume

• As you increase the temperature of a gas the
  particles move further away from each other.
• This means that the volume will increase when the
  temperature increases and volume decreases when
  temperature decreases.

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Relate Temperature, Volume, and Pressure
Temperature and Volume

• As the temperature increases and the gas
  particles move further away from each other, the
  gas becomes less dense.
• This is what makes a hot air balloon fly.
• The air in the balloon is warmer and therefore
  less dense.
• Since the air in the balloon is less dense than
  the surrounding air, the balloon will rise and
  floaton cooler denser air.

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Relate Temperature, Volume, and Pressure
Temperature and Pressure

• As the temperature in an enclosed container
  increases and the gas particles move faster they
  hit the walls of the container with more force.
• This means that the pressure inside the container
  will increase when temperature increases.

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Relate Temperature, Volume, and Pressure
Temperature and Pressure

• As the temperature in a container increases, the
  gas particles move faster and the pressure
  increases.
• This is the principle behind a pressure cooker.
• As the heat increases inside the sealed pot, the
  pressure also increases.
• The food cooks faster because of the increased
  pressure.

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Relate Temperature, Volume, and Pressure
Pressure and Volume

• As the pressure on a gas increases, the space the
  gas occupies is decreased.
• This means that the volume will decrease when
  pressure increases and volume will increase when
  pressure decreases.

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Relate Temperature, Volume, and Pressure
Pressure and Volume

• As the pressure on a gas increases, the space the
  gas occupies decreases.
• If you bought a tank of propane gas to use with
  your gas grill, the gas would be under pressure.
• Putting a gas under pressure can decrease its
  volume. This means that you can store more
  propane particles in the same amount of space.

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Relate Temperature, Volume, and Pressure
Review

• The factors Temperature and Volume are directly
  related because as one increases the other
  increases and if one decreases the other
  decreases.
• Temperature and Pressure are also directly
  related because they go up and down together.
• Pressure and Volume are indirectly related
  because as one increases the other decreases.

Temperature ____ Volume ____Temperature ____
Pressure ____Pressure ____ Volume ____
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Relate Temperature, Volume, and Pressure
Home

• The relationships you just studied are often
  called the Gas Laws because they govern the
  behavior of gases.

• Complete the statements below to summarize the
  Gas Laws

decreases
decreases
If Temperature ___________ then Volume
____________
If Temperature ___________ then Pressure
____________
decreases
decreases
If Pressure ___________ then Volume ____________
decreases
increases
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Use the Gas Laws to Solve Problems
Home

• The relationships described by the Gas Laws can
  be used to calculate temperatures, volumes and
  pressures.

• The following is an example of the type of
  problem you will solve.
• 4 liters of air is heated from 0C until its
  volume reaches 4.5 liters. What is the final
  temperature?
• However, before you start calculating there are
  some things you must know.

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Use the Gas Laws to Solve Problems
Ex. 4 liters of air is heated from 0C until its
volume reaches 4.5 liters. Whats the final
temp?
?You must remember the relationships between
Temperature, Volume, Pressure
Temperature ____ Volume ____Temperature
____ Pressure ____Pressure ____ Volume
____
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Use the Gas Laws to Solve Problems
273 K
liters
Ex. 4 liters of air is heated from 0C
until its volume reaches 4.5 liters. Whats the
final temp?
liters.
Volume Any volume unit (liters, ft3, etc) is
suitable as long as you are consistent from
beginning to end

• You will need to determine appropriate units of
  measure for each factor. Temperature, Pressure,
  and Volume.

Pressure Any pressure unit (torr, lb/in2, etc)
is suitable as long as you are consistent from
beginning to end.
Temperature When solving gas law problems all
temperatures MUST be in KelvinK C 273
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Use the Gas Laws to Solve Problems
Ex. 4 liters of air is heated from 273 K until
its volume reaches 4.5 liters. Whats the final
temp?
? You will need to distinguish between the
initial and the final conditions stated in the
problem
V1 4 liters
V2 4.5 liters
T2 ?
T1 273 K
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Use the Gas Laws to Solve Problems
Ex. Air at standard temperature and pressure
occupies a volume of 8 liters. What will the
volume be if the pressure is doubled and the temp
goes to 298 K ?
Standard Temperature Standard Temperature 273
K Remember, temperature is always in Kelvin.
? Sometimes problems will make reference to
standard temperature and pressure. You need to
know the values associated with these standards
Standard Pressure Standard Pressure 1
atmosphere 760 mm Hg 760 torr 14.7
lb/in2 Remember, pressure can be in any units as
long as you stay consistent from the initial to
the final conditions.
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Use the Gas Laws to Solve Problems

• 4 liters of air is heated from 0C until its
  volume reaches 4.5 liters. What is the final
  temperature?

Step 3 Start your calculation with the initial
condition that has no pair. Set the problem up
as a conversion factor.
Step 4 Determine the correct position for the
remaining pairs of factors. Which one goes on
top and which one goes on the bottom.
Step 5 Perform the calculation.
Step 1 Identify and record the initial and
final conditions.
Step 2 Check for appropriate units of measure.

Now, lets actually solve some problems.
4 liters
4.5 liters
V1
V2
T2
307 K
T1
0 C
273 K
Temp must be in Kelvin. K C 273 0C 273 K
There is an initial temperature but no final
temperature. So start with the 273 K
In this problem the volume is going UP from 4
liters to 4.5 liters
Ask yourself, What will happen to the temp if
the volume goes up? The temperature will go up
as well.
The final temperature must get bigger. So, we
will put the larger volume on top and the smaller
on the bottom
273 K
4.5 l
307 K

4 l
1
273 x 4.5 ? 4 307
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Use the Gas Laws to Solve Problems

• A car tire is inflated to 36 lb/in2 on a 90F
  day. If the temp drops to 0 F, what would the
  pressure be?

Step 3 Start your calculation with the initial
condition that has no pair. Set the problem up
as a conversion factor.
Step 4 Determine the correct position for the
remaining pairs of factors. Which one goes on
top and which one goes on the bottom.
Step 5 Perform the calculation.
Step 1 Identify and record the initial and
final conditions.
Step 2 Check for appropriate units of measure.

90 F
0 F
T1
T2
305 K
255 K
P2
30 lb/in2
P1
36 lb/in2
Temp must be in Kelvin. C 5/9(F 32) K C
27390 F 305 K 0 F 255 K
There is an initial pressure but no final
pressure. So start with the 36 lb/in2
In this problem, the temperature is going DOWN
from 305 K to 255 K
Ask yourself, What happens to the pressure if
the temp goes down? The pressure will go down
as well.
The final pressure must get smaller. So, we
will put the smaller temp on top and the larger
on the bottom.
36 lb/in2
255 K
30 lb/in2

305 K
1
36 x 255 ? 305 30
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Use the Gas Laws to Solve Problems

• A bike tire has a volume of 46 in3 and is
  inflated to 65 lb/in2 . If the volume increased
  to 60 in3, what would happen to the pressure?

Step 3 Start your calculation with the initial
condition that has no pair. Set the problem up
as a conversion factor.
Step 4 Determine the correct position for the
remaining pairs of factors. Which one goes on
top and which one goes on the bottom.
Step 5 Perform the calculation.
Step 1 Identify and record the initial and
final conditions.
Step 2 Check for appropriate units of measure.

46 in3
60 in3
V1
V2
P2
50 lb/in2
P1
65 lb/in2
in3 are units of volume and they are consistent
from initial to final.lb/in2 are units of
pressure
There is an initial pressure but no final
pressure. So start with the 65 lb/in2
In this problem, the volume is going UP from 46
in3 to 60in3
The final pressure must get smaller. So, we
will put the smaller volume on top and the larger
on the bottom.
Ask yourself, What happens to the pressure if
the volume goes up? The pressure will go down.
65 lb/in2
46 in3
50 lb/in2

60 in3
1
65 x 46 ? 60 50
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Use the Gas Laws to Solve Problems

• Air at standard temp and pressure occupies a
  volume of 8 liters. What will the volume be if
  the pressure is doubled and the temp goes to 25
  C ?

Step 3 Start your calculation with the initial
condition that has no pair. Set the problem up
as a conversion factor.
Step 4 Determine the correct position for the
remaining pairs of factors. Which one goes on
top and which one goes on the bottom.
Step 5 Perform the calculation.
Step 1 Identify and record the initial and
final conditions.
Step 2 Check for appropriate units of measure.

T1
273 K
T2
25 C
298 K
P1 x 2
P1
760 torr
P2
1520 torr
8 liters
V1
4.4 liters
V2
The final volume must get smaller.So, we will
put the smaller pressure on top and the larger on
the bottom.
T2 must be in Kelvin 25 C 298 K The other
units are appropriate and consistent from
beginning to end.
In this problem, there are 2 changes.The
pressure is going up as well from 760 torr to
1520 torr
Ask yourself, What happens to the volume if the
pressure goes up?The volume goes down.
There is an initial volume but no final volume.
So start with the 8 liters.
In this problem, the temperature is going UP
from 273 K to 298 K
The final volume must get bigger. So, we will
put the bigger temp on top and the smaller on the
bottom.
Ask yourself, What happens to the volume if the
temp goes up? The volume will go up.
Standard Temp 273 KStandard Pressure 760 torr
8 liters
298 K
760 torr

4.4 liters
273 K
1520 torr
1
8 x 298 ? 273 x 760 ? 1520 4.4
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Use the Gas Laws to Solve Problems
Practice
The following slides will present one or two
practice problems of each type. Try them on your
own before you click for the answers
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Use the Gas Laws to Solve Problems

• Air at 260 K has a pressure of 750 mm of Hg. If
  the temperature increases to 292 K, what is the
  new pressure?

292 K
750 mm Hg
842 mm Hg
260 K
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Use the Gas Laws to Solve Problems

• 10 liters of air is at 770 torr. What is the
  volume if the pressure drops to 730 torr?

770 torr
10 liters
10.5 liters
730 torr
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Use the Gas Laws to Solve Problems

• 2 cubic feet of gas is at 30 C. What will its
  volume be if the temperature drops to 15 C?

288 K
2 ft3
1.9 ft3
303 K
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Use the Gas Laws to Solve Problems

• Propane in a 2 ft3 tank is under 150 lb/in2 of
  pressure. If the tank became dented so the
  volume dropped to 1.8 ft3, what would happen to
  the pressure?

2 ft3
150 lb/in2
167 lb/in2
1.8 ft3
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Use the Gas Laws to Solve Problems

• A quantity of air is at standard temperature and
  pressure. If the pressure is decreased to 0.75
  atmospheres, what is the new temperature?

0.75 atm
273 K
205 K
1 atm
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Use the Gas Laws to Solve Problems

• 5 liters of gas at 41 F increases to volume of
  5.5 liters. What is the new temperature in F?

5.5 liters
305.8 K 91 F
41 F 278 K
5 liters
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Use the Gas Laws to Solve Problems
Home

• Air at standard temperature and pressure occupies
  a volume of 15 liters. What will the volume be
  if the temperature decreases to -10 C and the
  pressure drops to 740 torr.

263 K
760 torr
15 liters
14.8 liters
273 K
740 torr
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Technical Science Introduction to Chemistry

• You have Completed
• States of Matter