Chem chp 2 Flashcards
What is the definition of matter?
Matter is a substance that has mass and occupies space. All living and non-living things are matter.
What state is dry ice considered to be in?
Solid
What are the three main states of matter?
Solid, liquid and gas
State the particle arrangements for the 3 states of matter
Solid-packed in close and orderly manner
Liquid-closely packed in disorderly manner
Gas- very far apart in disorderly manner
State the attractive forces between particles of the 3 states of matter
Solid- Very strong
Liquid-Less strong
Gas-Very weak
State the kinetic energy of particles of the 3 states of matter
Solid- very low
Liquid- low
Gas- high
What is the particle movement of solids?
Vibrate and rotate about fixed positions
What is the particle movement of liquids?
Slide past one another freely throughout the liquid
What is the particle movement of gases?
Move quickly and randomly in any direction
Define transition temperatures
Transition temperatures are the specific temperatures where heating or cooling of a substance results in ** changes of state** instead of changes in temperatures.
What is temperature?
The measure of the average kinetic energy of particles in a substance.
What happens during changes of state (energy-wise)?
Temperature remains constant as the avg KE of particles does not change.
Thermal energy->CPE and vice versa
Describe melting
KE gained->particles in solid vibrate and move faster when heated
sufficient energy
->overcome forces of attraction holding them in their fixed positions and move around one another randomly.
Describe freezing
Particles in liquid slow down
Thermal energy lost to surroundings when liquid is cooling->KE decreases
Particles eventually settle into fixed positions in an orderly arrangement
Solid is formed
Describe expansion
Solid heated at temps below boiling pt-> cannot spread out freely, strongly attracted
Vibrate more quickly, but with wider spacing
Describe contraction
When solid is cooled, thermal energy is transferred from the particles to the surroundings
Particles possess less kinetic energy
->vibrate slower and closer
Define evaporation
The process by which a liquid changes to a gas at temperatures lower than its boiling point.
Define boiling
The process by which s liquid changes to a gas throughout the liquid at the boiling point of the substance.
Describe evaporation
At surface of liquid (in contact with air)-> enough KE to overcome attractive forces
‘Escapes’ liquid as vapor
At what temperature does evaporation occur
At all temperatures
Where in the liquid does evaporation occur?
At the surface, when only some particles have enough energy to escape as a gas
Describe boiling
CLUE: talk ab energy transfer and forces of attraction
thermal energy transferred (at boiling pt.)-> gain KE->Particles in liquid move faster
gain sufficient energy->completely overcome forces of attraction holding them tgt
What are the differences between evaporation and boiling?
where it occurs-> on surface (evaporation) vs throughout entire liquid (boiling)
what temp it occurs at-> any temp (evaporation) vs only at boiling pt (boiling)
speed-> slow process (evaporation) vs fast process (boiling)
Define condensation
The process by which a gas changes to a liquid
Describe condensation
Gas is cooled, KE-> thermal energy transferred to surroundings
Spacing between particles reduces when cooling->volume of gas decreases
gas contracts until particles come close enough form a liquid
When does condensaion occur?
When water vapour touches a cold surface
What does liquifying gases do?
Shrinks volume of substance by a significant amount, makes it easy for storage
Define sublimation
The process by which a solid changes directly to a gas without going through the liquid state.
Define vapour disposition
The process by which a gas changes directly to a solid without going through the liquid state
Describe sublimation
Thermal energy from surroundings ->more KE
Particles at surface of solid have enough **KE **to break away from solid and escape as gas
Describe vapour disposition
Particles in gas cool until they slow down and arrange themselves directly into solid state
What is the effect on molecular mass on diffusion?
greater Rmm, particles move slower and rate of diffusion is slower
smaller Rmm, particles move faster and rate of diffusion is faster
