Chapt. 9: Kinetic Model of Matter

Question 1

What is the arrangement of particles in a solid?

Answer 1

• Closely packed together in a regular pattern, occupying minimal space
• Large number of particles per unit volume
  -> Hence solids have highest densities

Question 2

What is the particle movement of a solid?

Answer 2

• they vibrate about their fixed positions, held tgt by very strong attractive forces between particles
  -> Hence solids have fixed volume and shapes

Question 3

What is the arrangement of particles of a liquid?

Answer 3

• Randomly arranged, with particles slightly farther apart than in solids
• Slightly smaller number of particles per unit vol. compared to solids
  -> Hence, liquids have relatively high densities

Question 4

What is the movement of particles in a liquid?

Answer 4

• Particles are free to move about within the liquid and slide past one another. There are attractive forces between the particles.
  -> Hence, liquids have fixed volumes, but not fixed shapes.

Question 5

What is the arrangement of particles in a gas?

Answer 5

• Randomly arranged and very far apart from one another
• Small number of particles per unit volume
  -> Hence, gases have very low densities

Question 6

What is the movement of particles in a gas?

Answer 6

• Very little attraction between particles, move arnd randomly at high speeds and occupy any available space
  -> Hence, gases have no fixed vol and shape, and can be easily compressed.

Question 7

What is the pressure of gas due to?

Answer 7

• When air molecule collides with the inner wall of the container, a force is exerted by the particle on the wall.
• By Newton’s 3rd Law of motion, a force, equal in magnitude but opposite in direction, will be exerted by the wall on the molecule.
• As these collisions btw air molecules and the wall are numerous, this will result in an average force being exerted by the molecules on the wall.
• As pressure = Force/Area, hence the pressure of the gas is due to the collisions of the gas molecules with the walls of the container.

Question 8

What is the effect of temperature on the movement of particles?

Answer 8

• When the temperature of the gas increase, this causes the average KE of the air molecules to increase as well.
• Gas molecules will have a higher avg speed at higher temperatures.
• The faster-moving gas molecules will bombard the other gas molecules more vigorously and frequently, causing the other gas molecules to move faster and change direction more frequently.

Question 9

What is the relationship between the pressure and temperature of a gas?

Answer 9

• When the object is moving, this causes the container to be heated, hence the temperature of the air in the container will also rise.
• Using the kinetic model of gases, a rise in the temperature of the air will cause an increase in the avg speed of the air molecules.
• The air molecules bombard the inner surface of the container more vigorously and more frequently.
• The avg force per collision between the air moles and the wall of the tyre increases, and since the volume of the gas remains constant, the pressure inside the container will increase.

TL;DR: Pressure is directly proportional to temperature. [Volume remains constant]

Question 10

What is the relationship between the pressure and volume of a gas?

Answer 10

• Using the kinetic model of gases, a decrease in the volume of the gas means that the number of gas molecules per unit volume increases.
• Gas molecules will collide more frequently with the inner surface of the container, resulting in a greater avg force.
• As pressure = Force/Area, hence the gas pressure will increase.

TL;DR: Pressure is inversely proportional to the volume. [Temperature remains constant]

Question 11

What is the relationship between the volume and temperature of a gas?

Answer 11

• Using the kinetic model of gases, a rise in the temp of a gas will result in the avg speed of the gas molecules.
• The heated gas molecules will collide more vigorously and more frequently with the inner surface of the flask.
• As gas pressure increases, and when it exceeds atp, a net upward force acts on the container, keeping the pressure constant.
• As the vol of the container increases, this will result in the pressure of the gas decreasing.

TL;DR: Volume is directly proportional to the temperature. [Pressure remains constant.]