changes of state

Question 1

what is the strength of forces between particles determined by? (3)

Answer 1

1. the material ( which determines type of bond and the structure)
2. temperature
3. pressure

Question 2

arrangement, movement and relative energy of SOLIDS

Answer 2

• strong forces of attraction so solids are held tightly together
• low energy
• only vibrate on the spot
• expand when heated because particles are vibrating more

Question 3

arrangement, movement and relative energy of GASES

Answer 3

• weak forces of attraction between particles so particles are free to move
• very far apart
• more energy than liquids and solids

Question 4

arrangement, movement and relative energy of LIQUIDS

Answer 4

• weaker forces of attraction than solids
• stick closely together but free to move past each other
• more energy than solids but less than gases

Question 5

solid to liquid (and its energy change)

Answer 5

melting - heat taken in because energy is needed to break bonds holding together as a solid

Question 6

liquid to gas (and its energy change)

Answer 6

boiling - heat taken in because energy is needed to break bonds holding together as a liquid

Question 7

gas to liquid (and its energy change)

Answer 7

condensation - heat given out as particles bond together in the liquid

Question 8

liquid to solid

Answer 8

freezing - - heat given out as particles bond together in the solid

Question 9

what is evaporation (and how is it different to boiling)?

Answer 9

• also a change of state from liquid to gas
• can happen at a much lower temperature than the boiling point
• particles in the liquid have a variety of energies so SOME at the surface have enough energy to overcome the forces between the particles to become a gas
• in boiling ALL of the particlees have eough energy to overcome forces of attraction and become gases

Question 10

why do cooling/heating graph have flat sections?

Answer 10

the energy is being used to overcome the force of attraction instead of to raise the temperature so as the substance changes state the temperature remains constant

Question 11

solid to gas

Answer 11

sublimation

Question 12

what will impurities in a substance do to its melting point?

Answer 12

decrease

Question 13

what will impurities in a substance do to its boiling point?

Answer 13

increase

Question 14

what is the effect of temp on solubility of solids?

Answer 14

solubility increases as temp increases

Question 15

what is the effect of temp on solubility of gases?

Answer 15

solubility decreases as temp increases

Question 16

kinetic theory (3 main points)

Answer 16

1. all matter made from invisible, moving particles
2. move all the time, the higher the temp the higher they move
3. heavier particles move more slowly than light ones at a given temp