Exam Revision

Question 0

kinetic theory - liquids

Answer 0

• particles in liquids are much closer, however they can constantly change positions
• liquids can not be compressed due to a lack of space between particles
• attractive forces between liquids are fairly weak
• strong enough to keep the liquid particles together and so give the liquid a definite volume

Question 1

Kinetic Theory- volume will change if temp changes

Answer 1

• as the temperature of the gas decreases, the average kinetic energy and the average velocities of the particles will decrease
• therefore, gas particles will collide with the wall less frequently
• this causes the gas pressure inside the container to decrease
• this works both ways, increase temp causes an increase in average kinetic energy of the gases therefore increasing gas pressure inside the container

Question 2

• kinetic theory - solid

Answer 2

• movement of particles are much more restricted than in liquids
  particles in a solid ate closer together in a liquid
• attractive forces in a solid> than that of a liquid
• solids have a fixed shape and volune

Question 3

temperature

Answer 3

• measure of the average kinetic energy of the particles in a substance

Question 4

• heat

Answer 4

• thermal energy

- energy transferred between objects that are at different temperatures

Question 5

changes in state

Answer 5

• PURE substances undergo changes of state at a definitive temperature

Question 6

• evaporation

Answer 6

• all particles of a liquid possess a range f kinetic energies
• some may have more,
• if a particle bear the surface of the liquid has sufficient kinetic energy, it maybbe able to escape from thr attractive forces of its neighbouring particles + become a gass

Question 7

vapour pressure

Answer 7

• liquid is placed in a container, and then sealed, amount of liquid will decrease
• many particles will jump to gaseous state, but then be condensed into liquid state
• evaporation and condensation occurs at the same time
• rate of evap. = rate of conden
• evaporated gases in a closed container causes a pressure
• this pressure is known has vapour pressure of a liquid

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Question 8

boiling point

Answer 8

• bubbles form of steam
• bubbles can only form when the vapour pressure of the water equals the atmospheric pressure exerted at the liquid’s surface
• ## any change in atmospheric pressure, causes a change in boiling point

Question 9

molecule

Answer 9

• small group of atoms strongly bonded together

- eg water

Question 10

covalent bond model

Answer 10

• atoms in a molecule share electrons

- held by electrost