Phys - Kinetic & Thermal

Question 1

NISCER

Answer 1

Negligible volume
Intermolecular forces
Straight lines
Constant motion
Elastic collisions
Random distributed energy & motion

Question 2

Zeroth Law of Thermodynamics

Answer 2

Temperature is transitive

Question 3

First Law of Thermodynamics

Answer 3

In a closed system, energy remains constant.

U = Q - W

Question 4

Second Law of Thermodynamics

Answer 4

Heat flows from hot to cold, all systems move towards homogeneity.

Question 5

Third Law of Thermodynamics

Answer 5

As the temperature of a system approaches zero, its entropy also approaches zero.

Question 6

Molar Mass

Answer 6

System to measure mass where 1mol = number of atoms in 12g of C-12 = 6.02x10^23

Molar mass of C-12 is 12gmol^-1

Question 7

Relationship between V & p (boyles)

Answer 7

1/V ∝ p

p1V1 = p2V2

Question 8

Relationship between V & T (charlie)

Answer 8

V ∝ T

V1/T1 = V2/T2

Question 9

Relationship between p & T (gay)

Answer 9

p ∝ T

p1/T1 = p2/T2

Question 10

Deriving pV = 1/3 Nmc^2

Answer 10

1. Draw container and label all side lengths & mass and velocity of a particle
2. Momentum change & time taken between the same wall collision
3. Find pV
4. Velocity can be in any direction, so find c = sqrt(vx^2 + vy^2 + vz^2)
5. On average, only 1/3 particles will travel in one plane.

pV = 1/3 Nmc^2

Question 11

How Gas Exerts A Pressure

Answer 11

A gas particle collides with a wall of its container and a force is exerted on the particle by the wall, causing it to bounce back into the container. Due to N3L, an equal and opposite force is exerted on the wall of the container and a pressure is felt per unit area.

Question 12

Physical Processes of Variables / Increase in Temperature

Answer 12

Molecules move randomly
Collisions become more frequent when heat is supplied
Fixed volume causes increase in internal energy
Work done is zero
U = kT, so temperature increases

Question 13

Physical Processes of Variables / Increase in Pressure

Answer 13

Molecules collide with walls exerting force
Pressure is the force on walls per unit area
P = kT, pressure increases
Mean pressure due to many collisions increases

Question 14

Physical Processes of Variables / Increase in Volume

Answer 14

Molecules move randomly
As heat flows into the system, molecules collide with walls more frequently
Momentum of molecules increases
N2L, F = rate of change of momentum when colliding with wall
N3L, force on walls equal and opposite to force exerted on molecules by walls
More force on collisions, volume increases