Chapter 15 - Gas Laws

Question 1

What is a Mol ?

Answer 1

The SI unit of measurement for the amount of substance.
One mole is equal to the amount of a substance which contains as many atoms as there are in 12g of carbon-12

Question 2

What is the value of the Avogadro constant?

Answer 2

6.02x10^23

Question 3

What assumptions are made about ideal gasses?

Answer 3

Atoms or mollecules have random directions and speeds
Atoms or mollecules take up a negligable volume
The collisions are all completely elastic
Time of colisions is negligable compared to time between
Electrostatic forces between are neglegable except during collisions

Question 4

What changes when an atom collides with a container wall?

Answer 4

Velocity changes but speed does not

Question 5

What is an ideal gas?

Answer 5

It is a gas which obeys all 3 of the gas laws

Question 6

What is the equation of state?

Answer 6

pV = nRT

Question 7

What is Boyle’s law?

Answer 7

Pressure and volume of gas are inversly proportional at constant temperature

Question 8

What is Charles’ law?

Answer 8

The volume fixed mass gas is directly proportional to its absolute temperature at a constant pressure.

Question 9

Define the quantities in the equation PV = nRT

Answer 9

P - pressure
V - volume
n - number of moles
R - gas constant
T - absolute temperature

Question 10

What is the Boltzman constant?

Answer 10

The gas constant for one molecule of gas

Question 11

The gas constant R is measured per what?

Answer 11

R is the constant per mole of gas

Question 12

How can Newtons laws be used to explain pressure of an ideal gas?

Answer 12

• According to Newtons 1st law the particles move with constant velocity unitl they collide with a wall of the container or another particle
• When the particles collide with the walls according to Newtons 3rd law they exert a force on the wall and the wall exerts and equal and opposite force
• As there is a significant number of particles and their motion is random the collisions will be spread across the surfaces of the container

Question 13

What assumptions are made about particels in an ideal gas?

Answer 13

• The particles move raondomly
• The volume of the particles is negligable
• The collisions of the particles are perfectly elastic
• The duration of collisions is negligable compared to the time between collisions
• The volume of particles is negligable compared to the volume of the gas

Question 14

How do you calculate the root mean squared speed?

Answer 14

It is the square root of the mean of the squared speeds

Question 15

What does the shape of a speed distribution graph depend on?

Answer 15

The temperature

Question 16

What happens to the speed distribution graph as the temperature increses?

Answer 16

• Average speed increases
• Maximum speed increases
• Curve becomes more spread out

Question 17

Why may some gas particles have different kinetic energy within a gas?

Answer 17

The particles are constantly colliding and transfering energy so some will have more than others