Gases NotesName______
Period______Date______
12.1 A. Physical Properties:
1. Gases have ______. The density is much smaller than ______or
______, but they have mass.
2. Gases can be ______. Very easy to reduce the ______
of a gas. Example: ______
3. Gases completely ______their containers.
4. Gases can ______through each other rapidly. Example the
______of food smells and perfume.
5. Gases exert ______.
6. The ______of a gas depends upon ______.
High Temp. = ______pressure, low temp. = ______pressure.
B. Kinectic - Molecular Theory:
1. Gases are ______particles that have ______. These particles are
usually molecules, except for the ______.
2. The particles in gases are separated by relatively ______distances.
3. The particles in gases are in constant rapid ______(random).
4. Gases exert pressure because their particles frequently ______
with the walls of their ______and each other.
5. Collisions of gas particles are perfectly ______.
6. Temperature of a gas is simply a measure of the ______energy of
the gas particles. High temp. = ______K.E., Low temp. = ______K. E.
7. Gas particles exert no ______on one another. Attractive forces are so
______between particles they are assumed to be ______.
C. Measuring Gases:
1. The following 4 variables will be used to do gas calculations:
______- amount of a gas, it is measured in ______
______- volume of a gas, it is measured in ______
“STP” = Standard Temperature & Pressure:
______- Standard Temperature:______oC = ______K
Taken in oC converted to Kelvin (K) T(K) =
Ex #1) 22°C = ______K 100.°C = ______K
-27.3°C = ______K -273°C = ______K
______- Standard Pressure: can be measured using the following units:
(sea level pressure)
______atm (atmospheres) ______mm Hg
______Pa (Pascals)______torr
______kPa (kilopascals)______lb/in2 (psi)
Ex #2) Convert 1.026 atm to kPa:
Ex #3) Convert 98,500 Pa to mm Hg:
2. Atmospheric pressure is the pressure exerted by the ______in the atmosphere.
This pressure varies with altitude and ______
3. Atmospheric pressure is measured with a ______. This is a glass tube
sealed at one end and filled with Hg.
12.2 The Gas Laws
A. Boyle’s Law: Pressure - Volume Relationship. The pressure & volume of a sample of
gas at constant ______are ______proportional to each
other.
Ex #4) A gas has a volume of 300. mL under a pressure of 740. mm of mercury. If the temperature
remains constant, calculate the volume when under a pressure of 750. mm.
B. Charles’ Law: Temperature - Volume Relationship. At constant ______
the volume of a fixed amount of gas is ______proportional to its absolute
______.
* Temperatures must be in Kelvin!!
K = oC + ______
Ex #5) What is the Celsius temperature of 68.20 mL of methane, if it occupies a volume of
0.02200 L at 50.0 oC?
C. Avogadro’s Law: Amount - Volume Relationship. Equal ______of gases at
the same ______and ______contain an
______number of particles.
1 mole gas = ______= 6.02 x 1023 particles at STP (273 K & 1 atm)
Therefore because of Avogadro’s Law if these three gases are at the same temperature and pressure,
they must take up the same ______.
D. Dalton’s Law of Partial Pressures: The sum of the partial ______
of all the components in a gas mixture is equal to the total ______
of the gas mixture.
Ex #6) A flask contains a mixture of oxygen, argon, and carbon dioxide with partial pressures
of 745 torr, 0.278 atm, and 391 torr respectively. What is the total pressure in the
flask?
Ex #7) The total pressure of a mixture of helium and neon is 498 mm Hg. If helium is 20.0 % of the mixture, what is the partial pressure of helium?
E. The Combined Gas Law: “Choyles” This law can be used to determine how changing two
variables at a time affects a ______variable.
Ex #8) A gas occupies 72.0 mL at 25 oC and 198 kPa. Convert these to standard conditions.
What is the new volume?
P1 =P2 =
V1 =V2 =
T1 =T2=
12.3
A.The Ideal Gas Law
Although no “ideal gas” exists, this law can be used to explain the ______
of ______gases under ordinary conditions.
P = ______
V = ______
n = ______
R = ______
universal gas constant
T = ______
B. Ideal Gas Law & The Kinetic – Molecular Theory:
- Under normal conditions (temperature & pressure) gases behave ______.
n ____P ____ (more gas, ______)
PV = nRT T ____P ____(moves faster, ______)
V ____P ____(smaller volume, ______)
- Gases at ______and ______do NOT behave
ideally. As you decrease the volume of a gas, the ______of the particles themselves
______. The Kinectic-Molecular Theory & Ideal Gas Law
assume that gas particles have ______of their own.
- Second, the ______which are very ______when
the particles are moving fast, become larger as they ______.
Ex #9) How many grams of carbon dioxide occupy a volume of 36.9 mL at 158 kPa and 72 °C?
C. Lifting Power of Gases:
- Uses a gas “______” than air (smaller ______mass.)
Ex) The Hindenburg used ______
Ex) Today’s blimps use ______
- Hot Air balloons heat air to lower its ______.
- Effusion is the movement of gas atoms or molecules through a hole so ______they
move one particle at a time. Smaller particles effuse ______than larger particles.
Ex) → →
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