chapter 14 - thermal physics

Question 1

what is the triple point?

Answer 1

the triple point is one specific temperature and pressure where all three phases of matter can exist in thermal equilibrium.

Question 2

what is the zeroth law of thermodynamics?

Answer 2

if two objects are each in thermal equilibrium with a third, then all three are in thermal equilibrium ( if A=B and A=C then B=C

Question 3

how do you covert from degrees Celsius to kelvin

Answer 3

K = C + 273

Question 4

why cant you go negative kelvin?

Answer 4

kelvin only goes down to 0 as you cant have negative kinetic energy.

Question 5

what is the kinetic model?

Answer 5

the kinetic model describes how all substances are made up of atoms or molecules.

Question 6

what is the arrangement of particles in a solid?

Answer 6

atoms are regularly arranged and packed closely together with electrostatic forces of attraction holding them in fixed positions. can vibrate so have kinetic energy.

Question 7

what is the arrangement of particles in a liquid?

Answer 7

they have more kinetic energy than in solids, can change positions and flow past each other. still close together.

Question 8

arrangement of particles in a gas?

Answer 8

more kinetic energy than in a liquid, much further apart from other particles, free to move around as they have negligible electrostatic forces, unless they collide with each other or wall, random speed and direction

Question 9

what is Brownian motion?

Answer 9

Brownian motion is the random, uncontrolled movement of particles in a fluid as they constantly collide with other molecules.

Question 10

what affects the density of a substance?

Answer 10

the spacing between atoms ( closer the particles are the more dense the substance)

Question 11

what is the internal energy of a substance?

Answer 11

the sum of randomly distributed kinetic and potential energies of atoms in a substance.

Question 12

how can you increase the internal energy of a body?

Answer 12

increase temperature - kinetic energy increases resulting in greater internal energy
- when substance changes state electrostatic potential energy increases while KE remains constant.

Question 13

what is the electrostatic potential energy in different states?

Answer 13

solid- electrostatic forces very large- electrostatic potential energy has large negative value
liquid- low negative value
gas- negligible forces therefore potential energy is 0

Question 14

define specific heat capacity?

Answer 14

the energy required per unit mass to change the temperature by 1 K

Question 15

why does it not matter interchanging k and C at large temperatures like a star?

Answer 15

because 273 is so small compared to temperature of a star that the difference is negligible

Question 16

what is the formula for specific heat capacity?

Answer 16

c= energy / ( mass x change in temperature)

Question 17

how to determine specific heat capacity in experiment?

Answer 17

E=PxT = I x V x T measure current and voltage put through electrical heater in certain time periods, measure the mass of substance. use formula c= ( IVT)/ Mass x change in temperature), insulate material so don’t lose heat.

Question 18

define specific latent heat?

Answer 18

energy required to change the phase of mass m of the substance while temperature remains constant.

Question 19

what is formula for specific latent heat?

Answer 19

L= energy/ mass

Question 20

what are the two types of latent heat?

Answer 20

latent heat of fusion- solid to liquid phase

latent heat of vaporisation- liquid to gas phase

Question 21

what is the relationship between the gradient of temperature against time curve and specific heat capacity?

Answer 21

the gradient is inversely proportional to the specific heat capacity ( gradient is steeper, SPC is smaller )