Topic 6 - Particle model

Question 1

density formula

Answer 1

density = mass / volume

Question 2

properties of solids

Answer 2

• strong forces of attraction between particles
• particles close together in fixed, regular arrangement
• particles only vibrate about fixed positions

Question 3

properties of liquids

Answer 3

• weaker forces of attraction between particles
• particles close together but can move past each other at low speeds

Question 4

properties of gases

Answer 4

• almost no forces of attraction between particles
• particles far apart and free to move
• particles travel in random directions at high speeds

Question 5

density of different states of matter

Answer 5

• density of solids is generally highest as particles are closest together
• more particles per unit of volume so more mass per unit of volume

Question 6

what is internal energy

Answer 6

the total energy that the particles have in their kinetic and potential energy stores

Question 7

what happens when the system is heated?

Answer 7

• transfers energy to its particles, which means they gain KE and move faster
• increasing the internal energy
• leads to increase in temperature

Question 8

what does the size of the temperature change depend on?

Answer 8

• mass
• what it is made of ( specific heat capacity )
• energy input

Question 9

when does the substance start to change state

Answer 9

• when the particles have enough KE to break the bonds holding them together

Question 10

why does the temp of the substance stay the same during change of state?

Answer 10

• ## all of the energy is used to break the intermolecular bonds rather than raising the KE of the particles

Question 11

why does the mass stay same during change of state?

Answer 11

• physical change rather than chemical
• number of particles doesn’t change : they’re just arranged differently
• mass is conserved

Question 12

specific latent heat

Answer 12

amount of energy needed to change 1 kg of a substance from one state to another without changing temp

Question 13

formula for SLH

Answer 13

energy = SLH * mass

Question 14

Boyle’s Law formula

Answer 14

P1 × V1 = P2 × V2

Question 15

effect of temperature on particle motion in gases

Answer 15

• gas particles constantly moving in random directions
• if you increase temp, you transfer energy into KE of particles
• they move faster and so there are more collisions that exert a greater force

Question 16

gas pressure

Answer 16

• when the gas particles collide with a surface they exert a force on it
• P = F/A
• this means they exert a pressure too

Question 17

effect of increasing temp on pressure

Answer 17

• increase frequency of collisions and the force that is exerted
• this increase pressure if volume is kept constant

Question 18

effect of increasing volume on pressure

Answer 18

• the particles become more spread out
• frequency of collisions decreases
• less force, therefore less pressure
  P and V inversely proportional