particle model of matter (p3) Flashcards
describe the arrangements of solids, liquids and gases:
solid: vibrate around a fixed point, regular pattern, very close together, high density (apart from polystyrene)
liquid: close together, no regular pattern, move around each other, high density
gas: particles far apart, no pattern, moving rapidly, low density
describe the density of a material:
- the mass for the given volume
e.g. bricks are high density as they have a high mass packed into their volume
what stores of energy do particles have in a material?
- potential energy (intermolecular forces and chemical bonds)
- kinetic energy
how do you calculate internal energy (the energy stored in a system by particles)?
potential energy + kinetic energy
what else is increased when we heat a material (e.g. heat a solid to a liquid by melting it)?
we increase the internal energy, as the kinetic energy increases (the particles move more energetically until they have enough energy to escape from their intermolecular bonds). liquid particles have more kinetic energy than solid particles, therefore kinetic energy increases.
what is the process called when a solid turns directly into a gas?
sublimation
are changes of state physical or chemical?
they’re physical, as if we reverse the change, the material recovers its original properties
describe evaporation:
when a liquid turns into a gas, but only on the surface of the liquid. only the particles on the surface have enough energy to evaporate.
what is the definition of specific heat capacity?
the amount of energy required to raise the temperature of 1kg of a substance by 1 degree celsius.
what is the latent heat of a substance?
the specific latent heat of a substance is the amount of energy required to change the state of one kilogram of a substance with no change in its temperature
what is the specific latent heat of fusion?
the energy required to change 1kg of a substance from a solid to a liquid with no temperature change
what is the specific latent heat of vaporisation?
the amount of energy required to change 1kg of a substance from a liquid to a vapour with no temperature change
describe gas pressure:
gas pressure is due to the particles of a gas colliding with the walls of its container, which exerts a pressure. by increasing the number of collisions each second or increasing the energy of each collision, we can increase the pressure (increase the temp. of the gas)
- pressure is measured in pascals (Pa)
how do particles collide with the container walls?
they collide at right angles to the walls, causing the gas pressure. by increasing the size of the container, we can reduce the gas pressure, as particles must now travel further to collide with the walls.
what is the correlation between the gas pressure and the volume?
they’re inversely proportional. if the volume increases, the gas pressure decreases, as they’re both constants.
