SP14: the particle model Flashcards
arrangement of particles in a solid:
-tightly packed in a regular arrangement
-vibrate about a fixed position
forces between particles in a solid:
strong
can solids keep their shape?
yes
can solids be compressed?
no
arrangement of particles in a liquid:
-particles are tightly packed but free to move past each other
-randomly arranged
-freely move around and last each other
-sit close together
can liquids keep their shape?
no
can liquids be compressed?
no
arrangement of particles in a gas:
-randomly arranged
-move quickly in all directions
-tar apart
forces between particles in a gas:
weak
can gases keep their shape?
no
can gases be compressed?
yes
density = mass/volume units
density in
mass in kg/g
volume in cm^3
when does something float?
if it is less dense than water
does hot water float on room temperature water & why?
yes as it is less dense than room temperature water
does cold water float on room temperature water & why?
no, it is less dense than room temperature water
steps of using a eureka can for irregular objects
- fill the displacement can/eureka can until the water is level with the bottom of the pipe
- place a measuring cylinder under the pipe ready to collect the displaced water
- carefully drop the object into the can and wait until no more water runs into the cylinder
- measure the volume of the displaced water
how to calculate the density of a cube
- use a ruler to measure the length (1), width (w) and height (h) of a steel cube
- calculate the volume of the cube using (I × w × h)
- place the metal cube on the balance and measure its mass
- use the measurements to calculate the density of the metal
how to calculate the density of a sphere
- use vernier callipers to measure the diameter of the sphere
- calculate the volume of the sphere using (4/3(pi)r^3)
- place the metal sphere on the balance and measure its mass
- use the measurements to calculate the density of the sphere
how to calculate the density of an irregular object
- place the object on the balance and measure its mass
- fill the displacement can/eureka can until the water is level with the bottom of the pipe
- place a measuring cylinder under the pipe ready to collect the displaced water
- carefully drop the object into the can and wait until no more water runs into the cylinder
- measure the volume of the displaced water
- use the measurements to calculate the density of the stone
how to calculate the density of a liquid
- place the measuring cylinder on the balance and measure its mass
- pour the water into the measuring cylinder
- use the measurements to calculate the density of the water
melting
solid to liquid
evaporation
liquid to gas
sublimation
solid to gas
condensation
gas to liquid
freezing
liquid to solid
what type of process is boiling?
an active process that takes energy
what type of process is evaporation?
a passive process, the liquid will slowly absorb energy from the surrounding area so that some of its particles will gain enough energy to escape the liquid
does mass change when state changes?
no
why are changes in state called physical changes?
the process can be reversed which is different to the changes seen in a chemical reaction, which cannot be reversed so easily
when a material is heated or cooled, two changes may happen to the particles within the material:
1.
-chemical bonds between the particles may form, break or stretch
-there is a change in the chemical potential store of energy in the material
2.
-particles within the material gain or lose speed
-there is a change in the thermal store of energy within the material
what happens to particles when they are heated?
particles speed up, vibrate more and gain