Cornell Notes- Ch. 10 & 12 SC.doc

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7 8 9 10 11 KMT through heating

and cooling a gas

Demos for discussion

HW: WS #1

The Gas Laws

CW: WS#2

HW: Boyle’s Law Lab

Combined through Scuba

HW: WS #3

Liquids and Solids

HW: WS #4

Molar Volume of a Gas

Lab-Due Tues

12 13 14 15 16

In Class: Begin Ch 10 and 12 review sheet

Chapter 10 and 12

review

Chapter 10 _{& 12 TEST}

States of Matter & Gas Laws- Chapters 10 & 12

10.1 The Kinetic Theory

Kinetic Theory of Gases- valid only at extremely ____________________________ 1. A gas is composed of particles, usually molecules or atoms

• _____________________________ • Insignificant volume

• ___________________ each other

2. The particles in a gas move ___________________________________________. 3. All collisions are perfectly _____ _________________.

Kinetic Energy

• When a gas is heated, it absorbs thermal energy. Some of this is converted to ______ ___________________________________________ the motion of particles.

• As a substance moves from solid to gas the KE increases

• Average KE of a gas is proportional to the _________________ temperature. • Particles at 200K have _____________ the KE of particles at 100K.

The Kelvin temperature scale is used because 0K (absolute zero) is the temperature at ____ ____________________________________________.

Gas Pressure

– results from the _______________________________________ with objects.

• Atmospheric pressure-___________________________________________________

• Are atmospheric pressures higher or lower in the mountains? _______________ Why? _____________________________________________________________________. Barometer- ____________________________________________________________. SI unit of pressure _________________

Standard atmospheric pressure = __________ kilopascals (kPa) or 1 atm 1 mm Hg = pressure needed to support a column of mercury 1 mm high

STP = __________________________________________

1 atm = _________________ = ________________ = _________________

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12.1 Variables That Describe a Gas Kinetic Molecular Theory (KMT)

States that:

• Gases are composed of particles that are considered to be _________________ with little ____________.

• These particles are spaced far apart from one another and are in constant ____________. • They collide in a perfectly _____________ manner so that energy is never lost.

Compressibility – a measure of how much the volume of matter decreases under pressure.

P = ___________________ V = ___________________ T = ___________________ n = ___________________

12.2 The Effect of Adding or Removing Gas In a System

Adding gas  increases # of particles  increases # of collisions  increases pressure Removing gas  decreases # of particles  decreases # of collisions  decreases pressure

 The number of particles of gas and pressure are _________________ related.  If you double the number of particles you will double the pressure.

The Effect of Changing the Size of the Container

 An increase in volume  a _________ in pressure

 A decrease in volume  an increase in pressure

 Volume and Pressure are _____________ related.

 If you cut the volume in half = pressure doubles

o Compressing a gas increases its pressure.

o Expanding a gas decreases its pressure.

The Effect of Heating or Cooling a Gas

Heating  increases KE  increases # of collisions  __________________ pressure Cooling  decreases KE  decreases # of collisions  _________________ pressure

 Kelvin temperature and pressure are directly related.

 If youdouble the Kelvin temp  double pressure

What would have more internal pressure? A balloon containing 2 mol He or a balloon containing 5 mol He?

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12.3 The Gas Laws

1. Boyle’s Law for Pressure-Volume Changes

 For a given mass of gas at constant temperature, the volume of the gas varies inversely with pressure.

 We “Boyle” Peas and Vegetables!

P

1

V

1

= P

2

V

2

or P

1

=

V

2

P

2

= V

1

Example:

A gas is collected in a 242 mL container. The pressure of the gas in the container is measured and determined to be 87.6 kPa. What is the volume of this gas at 101.3 kPa? Assume the temperature is constant.

2. Charles’ Law for Temperature-Volume Changes

 The volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant. **Temperature must be in Kelvin!**

 A Charlie Brown Christmas is on TV

V

1

= V

2

or V

1

T

2

= T

1

V

2

T

1

T

2

Example:

A sample of gas at 15o_{C and 1 atm has a volume of 2.58 L. What volume will this gas occupy at}

38o_{C and 1 atm?}

3. Gay-Lussac’s Law for Temperature-Pressure Changes

 The pressure of a gas is directly proportional to the Kelvin temperature if the volume is kept constant. **Temperature must be in Kelvin!**

P

1

= P

2

or P

1

T

2

= T

1

P

2

T

1

T

2

Example:

A 2.00 L flask contains helium gas at a pressure of 685 torr and a temperature of 0o_{C. What}

would be the pressure in a flask if the temperature is increased to 150.o_C?

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4. The Combined Gas Law

 By canceling out terms remaining constant, we can derive Boyle’s, Charles’, and Gay-Lussac’s laws.



“

Peas and Vegetables on the Table”

P

1

V

1

= P

2

V

2

T

1

T

2

Example:

If a helium-filled balloon has a volume of 3.40 L at 25.0o_{C and 120.0 kPa, what is its volume at}

STP?

A flask contains 1.4L of an ideal gas at 50.0o_{C and 1.44atm of pressure. If the gas is compressed}

to 0.7L and the temperature is raised to 100.0o_{C what will be the new pressure in the container?}

12.4 Real vs. Ideal Gases

Ideal gases

 Follow the gas laws at all conditions of temperature and pressure.  Ideal gases _________________________

o Real gases can be liquefied and sometimes solidified; ideal gases cannot.

o Gases are like students in the summer. They behave most ideally at high temperature and low pressure.

The Ideal Gas Law

 Allows us to include the amount of gas (moles) in our calculations.

_____________________ “

P

u

v

N

e

rt

”

P = pressure in atm V = volume in L

n = # of moles R = ideal gas constant = 0.0821

T = temperature in ___________

Example:

A 5.0 L flask contains 0.60 g O2 at a temperature of 22oC. What is the pressure (in atm) inside the flask?

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Avogadro’s Hypothesis

 Equal volumes of gases at the same temperature and pressure contain equal numbers of particles.  At STP 1 mol of particles of any gas, regardless of size of the particles, occupies ________. Dalton’s Law of Partial Pressure

 At constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures.

P

total

= _____________________________

Example:

Determine the total pressure of a gas mixture that contains nitrogen and oxygen if the partial pressure of the nitrogen is 725 mm Hg and the partial pressure of the oxygen is 426 mm Hg.

Gases are often collected by water displacement.

 The total of the gas pressure plus the water vapor pressure is equal to the atmospheric pressure.  When we work a problem like this we must always look up and subtract the water vapor pressure

to get the gas pressure.

Example:

A sample of N2 gas is collected by the downward displacement of water from an inverted bottle. What

is the partial pressure of the N2 gas at 20.0oC, if the atmospheric pressure is 752 mm Hg? The water

vapor pressure is 17.5 mm Hg at 20.0o_C.

Scuba Science

 SCUBA = Self Contained _______________________________ Apparatus o At the surface, pressure is 1 atm. It increases 1 atm for every 10 m

underwater. At 30 m, the pressure is 4 atm. At 40m, pressure of 5 atm would not allow you to inflate your lungs to breathe.

o Scuba gear increases the _______________________________________ as you descend, allowing normal breathing.

o If a diver ascends without exhaling, the increase in lung volume could cause the lungs to rupture. From 40m (5 atm) to the surface (1 atm), would cause the lungs to increase in volume ____________________!

o Divers may also experience “the bends”, a condition in which nitrogen dissolves in the blood at high pressures and then comes out as bubbles as the pressure is decreased,

__________________________.

10.2 The Nature of Liquids

• Liquids and solids are ____________________ states of matter • Liquids and gases ________________________________.

• Particles of a liquid are held together by _____________________ attractive forces.

State Changes

 __________________ -process by which a liquid changes to a gas or vapor.

• __________________- when gas molecules escape from the surface of a liquid.

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• Vaporization in open container

• As temperature increases, more molecules achieve enough energy to escape • _______________________is a cooling process (ex. Sweating)

• Highest energy (hottest) particles escape, leaving the cooler ones behind

Molecules at the surface are attracted to less molecules than are molecules in the interior. **Remember: must have enough energy to break the attractive forces for the liquid to vaporize. So, molecules with ____________________________will vaporize into a gas first

 ___________________ -Pressure produced in a ________________ container by vapor particles colliding with the walls

 As ____________________ increases, vapor pressure ___________________.

 Dynamic Equilibrium: ______________________________________________________

Boiling Point

• The temperature at which the vp of the liquid equals the external or atmospheric pressure. Normal bp = ________________________________________________________ • Mountains = _________ ___________ bp (Denver’s bp is 95ºC)

• Pressure cooker = _________ ____________ bp (bp above 100ºC)

• The temperature of a liquid _______________________________________________

10 Nature of Solids

Melting Point (MP)

– The temperature at which a __________changes into a ___ _________ – Vibrations are strong enough to overcome attractions forces

– Melting point = ___________________

– Ionic solids = ___________________ melting points (strong attractive forces) – Molecular solids = _______________ melting points (weak attractive forces)

Crystal

• Most __________________ are crystalline

• Atoms, ions, or molecules are arranged in an orderly, repeating, 3-D pattern called a ____ ____________________________

• ____ ____________- smallest group of particles within a crystal that retains the geometric shape of the crystal

• ______ ______- are two or more different forms of the same element in the same physical state. Carbon has ________ _______ allotropes.

Why does sweating cool you off?

What is the boiling point of water?

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These 4 Carbon allotropes are:

• _______ ________

– _____________________________________________________ – Dense

– Hard – Crystalline

• _____________________ – Loosely packed

– __________________________________

– __________________________________________________ – Crystalline

• __________________

– Includes Buckminsterfullerene (Buckyballs), a 60 carbon sphere • ____________

– Amorphous carbon (non-crystalline form)

• Other examples of Amorphous solids : ______________________________________