CH2 KINETIC PARTICLE THEORY Flashcards
What is matter?
A substance that has mass and volume.
What is the kinetic particle theory?
All matter is made of TINY PARTICLES and these particles are in CONSTANT RANDOM motion, COLLIDING with one another.
Describe the particulate characteristics for a solid.
- closely packed in an orderly manner
- held together by very strong forces of attraction
- vibrate about their fixed positions
- posses very low kinetic energy
Describe the particulate characteristics for a liquid
- closely packed in a disorderly manner
- held together by strong forces of attraction
- slide past one another freely
- posses low kinetic energy
Describe the particulate characteristics for a gas.
- far apart and arranged in a disorderly manner
- held together by weak forces of attraction
- move quickly and randomly
- possess high kinetic energy
When a substance changes in state, is this a physical or chemical change?
State changes are PHYSICAL changes as no new products are formed.
Describe the change in the arrangement of particles in a solid as it melts.
- Solid is heated. More T.E is converted to K.E. and the particles vibrate faster about their fixed positions
- Particles overcome forces of attraction between them and move further apart.
- Particles now slide past one another. Solid has melted into a liquid.
Why does melting/boiling/sublimation occur at a fixed temperature?
Energy from heating is used to overcome forces of attraction between the particles. Hence, the particles do not continue to gain K.E.
When state change occurs, do the particles continue to gain K.E.?
No
Describe the change in the arrangement of particles in a liquid as it boils.
- Liquid gains heat. More T.E is converted to K.E. and particles slide past one another faster.
- Particles overcome the strong forces between them and move further apart.
- Particles now move quickly and randomly. Liquid has boiled to form gas.
Describe the change in the arrangement of particles in a liquid as it freezes.
- Particles lose K.E and slide past one another more slowly
- Forces of attraction between particles become stronger and particles move closer to one another
- All particles vibrate about their fixed and orderly positions. Liquid has frozen into solid.
Describe the change in the arrangement of particles in a gas as it condenses.
- The particles lose K.E. and move more slowly
- Forces of attraction form between particles and the particles move closer together
- All particles slide past each. Gas has condensed into liquid.
Why does freezing/condensation happen at a fixed temperature?
heat lost during cooling is = heat released by the particles when they take up a more orderly arrangement
What are the differences between boiling and evaporation?
B: fast process E: slow process
B: bubbles are observed
E: no visible change
B: occurs throughout the whole liquid
E: occurs only at the exposed surface of the liquid
B: occurs at a fixed temperature
E: occurs at any temperature BELOW the boiling point
B: Source of energy needed
E: Energy supplied by the surroundings
What is sublimation?
The change from solid to gas without melting.
What are some substances that sublime?
Iodine, chloride, ammonium, dry ice
What is vapour deposition?
The change from gas to solid without condensation.
Why are gases, such as oxygen and nitrogen, stored as liquids when being transported?
- volume of the substances decreases significantly when in liquid state
- require less storage space
- transportation more efficient
Why do delivery companies use dry ice instead of ice cubes to keep frozen food cool during transport?
- The dry ice sublimates at a lower temperature than the melting point of ice cubes > it will keep food colder
- Unlike ice packs made from frozen water, dry ice evaporates into carbon dioxide and does not result in a liquid mess.
What is diffusion?
The NET MOVEMENT of particles from a region of HIGHER concentration to LOWER concentration, DOWN a concentration gradient, until equilibrium is reached.
What factors affect the rate of diffusion? Explain.
- Temperature
At higher temperatures, more T.E is converted to K.E. > able to move faster > increased rate of diffusion. - Particle mass
Particles with a larger mass require more K.E. to move at the same speed as lighter particles.
As K.E decreases, the rate of diffusion ______.
decreases
Explain why it is dangerous to keep dry ice in a sealed container at room temperature.
At room temp, dry ice sublimes into gaseous carbon dioxide. This causes a great increase in carbon dioxide increasing the pressure in the container. The container may explode.
