2.1.7 kinetic theory

Question 1

the ideal gas equation

Answer 1

pV = nRT or pV = NKT

Question 2

if we have N molecules, then the number of moles is:

Answer 2

n - N / NA

Question 3

what is conserved in an elastic collision

Answer 3

• momentum
• KE
• total E

Question 4

boyles law

Answer 4

the pressure of a fixed mass of a gas is inversely proportional to the volume at a constant temp

Question 5

charles law

Answer 5

vol of a fixed mass of a gas is proportional to its absolute T, provided p is constant

Question 6

pressure law

Answer 6

the pressure of a fixed mass of gas is proportional to its absolute T, provided v is constant

Question 7

combining the laws provided we have a fixed mass

Answer 7

pV/ T = constant

Question 8

assumptions around the KE theory of gas

Answer 8

• the molecules exert negligible forces on each other except when colliding. they move in straight lines between collisions
• collisions between molecules are elastic
• the molecules themselves occupy negligible vol compared with the vol of the container

Question 9

mean KE of one atom of an ideal gas

Answer 9

1/2mc^2 = 3/2kT

Question 10

a cylinder, fitted with a pressure gauge, contains an ideal gas and is stored in a cold room. when the cylinder is moved to a warmer room the pressure increases. explain in terms of the KE why increased pressure is expected

Answer 10

• heat (energy) transferred to gas from warmer air outside the mean KE of gas molecules increase
• moment of molecules increases
• more collisions per second
• each collision (with container walls) transfers more momentum
• force per unit area on container wall increases