Unit 1 - Matter and Energy - Gas Laws - Regents Flashcards
What is the Kinetic Molecular Theory? (3)
- Describes the behaviour of gases
- In terms of motion
- And relationships between gas particles
What does the Kinetic Molecular Theory explain?
Describes relationship of:
- Pressure
- Volume
- Temperature
- Velocity
- Frequency
- Force
between collisions of gas molecules
According to the Kinetic Molecular Theory, what is the volume of gases? (3)
- Gas particles have a negligible volume
- Most of the volume is empty space
- Gas can be compressed very easily because you are just removing a part of the empty space!
According to the Kinetic Molecular Theory, what is the relationship between gas particles? (4)
- Have neither attractive/repelling forces
- They don’t stick to each other OR push each other away
- Allows them to space out & fill up the whole volume
- If there were significant attractive forces, the gas particles would clump together, and the gas wouldn’t behave as freely compared to liquids and solids
According to the Kinetic Molecular Theory, how do you describe the collisions? (3)
- Collisions are Elastic
- No kinetic energy in the closed system is lost
- This helps predict gas behaviour
According to the Kinetic Molecular Theory, how do you describe transfer of energy? (4)
- When two gas particles collide, one slows down while they other speeds up!
- This means that kinetic energy was transferred between the particles
- However, in a closed system, although energy is getting transferred, the total kinetic energy in that system will always stay the same
- This explains why gases maintain a consistent temperature and pressure under stable conditions
Definition of Vacuum (4)
- Empty space
- No particles
- No collisions
- No Pressure
Definition of the Ideal Gas Model (4)
- Model that explains the behaviour of gases based on the KMT
- Low Pressure and High Pressure help represent the Ideal Gas Model
- L Pressure: Indicates less collisions
- H Temp: High KE can overcome attractive forces
HELPFUL: WHERE WOULD A GAS LIKE TO SPEND ITS VACAY? (BEACH HAS HIGHER TEMPERATURE AND LOWER PRESSURE)
What are two things you can do when molecules collide?
- Bounce apart
- React to form something new
Definition of Collision Therory
- In collisions, wiith proper energy and orientation
- Chemical reactions will occur
Definition of Pressure
A force exerted on a specific area
What is the kinetic - molecular view of gas pressure?
More Collisions = More Pressure
The greater amount of collisions means that there is a greater force. Therefore, since pressure is force/area, pressure increases
Standard Unit of Pressure
Pascal (Pa)
Atmospheric Pressure at sea level in KiloPascal
101.3 kiloPascal
Atmospheric Pressure at sea level in Atmospheres
1 Atmosphere
Atmospheric Pressure at sea level in millimeters of mercury
760 mm Hg
Atmospheric Pressure at sea level in Torr
760 Torr
What is the relationship between temperature and velocity?
The greater the average kinetic energy of the molecules, the greater the speed of those molecules
What is the relationship between mass (weight of particles) and the velocity?
The greater the mass, the lower the velocity
Analogy: Heavier molecules move more slowly because they need more energy to reach the same speed as lighter molecules.
Avogrado’s Hypothesis (4)
- Equal volumes of gases
- Same temperature
- Same Pressure
- Equal number of particles
Mnuemonic: S.T.E.V.E.N
Same Temperature, Equal Volume, Equal Number
Definition of Boyle’s Law (5)
- As long a temp. stays the same
- As Volume Decreases
- Pressure Increases
- When one goes up the other goes down
- Smaller volume means more collisions AND MOLECULES ARE EXERTING MORE FORCE AGAINST WALLS
Analogy: If you squeeze a balloon (decrease vol.), the air inside pushes harder against the balloon (increase pressure)
Let the balloon expand (increase the volume) and the pressure inside the balloon decreases.
Definition of Charles’ Law (4)
- If pressure stays the same
- When Temperature Increases
- Volume Increases
- Vice Versa - when one goes up, other goes down
Analogy:
Balloon is heated - expands
Balloon is cooled - contracts
How does pressure influence Charles’ law?
The container must get bigger when heated in order for the pressure to stay the same.
Why does an increase in temperature mean an increase in pressure (4)?
- Higher Temp = Higher KE
- Higher KE = Faster particles
- Faster particles = more collisions with container walls
- More collisions = Higher pressure
WHY will pressure stay the same when the volume increases in Charles’ law? (4)
- When the volume increases
- More room for faster moving particles
- Limits # of collisions
- Keeps pressure the same
When should you check the pressure - before or after?
After
What is the formula for Charles’ law?
Initial Volume/Initial Temperature =
Final Volume / Final Temperature
Definition of the Combined Gas Law (3)
- press. X vol /temp. of a system remains constant (RATIO)
- Combines Boyle’s Law and Charles’s Law
- If you change one factor, the others adjust PROPORTIONALLY to maintain equilibrium
What occurs if there is a fixed volume for gases? (4)
- Typically, if walls are flexible and gases are heated, it’ll expand and push those walls back
- However, if walls are rigid and gases are heated, the gas cannot expand
- So, the pressure will keep building up in that container
- If the pressure gets too high, the container will explode
Definition of Standard Pressure & Temperature (STP) (2)
- Standard conditions for temp. and pressure
- Used as a comparison
Formula for Boyle’s Law
P1V1 = P2V2
Formula for Charles’ Law
V1 / T1 = V2 / T2
