pressure + kinetic model of matter

Question 1

What is pressure? What is the formula for pressure (solid + liquid)?

Answer 1

Pressure is defined as force F acting normally per unit area A. P = f/a for solids, P = hpg for liquids

Question 2

What is Brownian motion?

Answer 2

Brownian motion refers to the random motion of tiny particles suspended in a fluid (smoke in air or pollen in water)

Question 3

How does gas pressure come about?

Answer 3

Gas molecules are in continuous, random motion. They collide with the walls of the container, exerting an average force on the walls. The force per unit area gives rise to pressure.

Question 4

Pressure is _____ proportional to temperature provided V is constant. Explain.

Answer 4

Pressure is _____ proportional to temperature provided V is constant. When temperature increases, the average kinetic energy of the particles increases, the particles move faster and collide with the surface of the walls of the container more frequently and vigorously. Thus, a greater force is exerted on the walls and average force per unit area increases, hence pressure of gas increases.

Question 5

Volume is _____ proportional to pressure provided T is constant. Explain.

Answer 5

Volume is inversely proportional to pressure provided T is constant. When volume decreases, the substance is compressed and the number of particles per unit volume increases. Thus, the particles collide with the container walls more frequently, and a greater force is exerted on the wall, average force per unit area increases and pressure of gas increases. (when T is constant, average kinetic energy of particles is constant)

Question 6

Volume is _____ proportional to temperature provided P is constant. Explain.

Answer 6

Volume is directly proportional to temperature provided P is constant. When temperature increases, average kinetic energy of particles increases, they hence move faster and collide with the walls of the container more frequently and vigorously. Thus, a greater force is exerted on the container wall and average force per unit area increases causing an increase in gas pressure. The increase in gas pressure causes the substance to expand until internal pressure = external pressure.

Question 7

What is Boyle’s law?

Answer 7

p1v1 = p2v2