chapter 14 the particle model Flashcards
use kinetic theory model to explain the different states of matter
solids are close together in a regular pattern, they vibrate in a fixed position, have a fixed shape because their particles cannot move from place to place, they cannot be compressed or squashed because the particles are close together and have no space to move into.
Liquids- close together random, move around each other, flow and take shape of their container, cannot be compressed or squashed as they particles are close together and have no space to move into.
Gases- far apart, random, move quickly in any direction, they flow and completely fill their container, they can be compressed or squashed because the particles are far apart and have space to move into.
what is the density equation
m
P = _
v
describe what happens when substances melt, freeze, evaporate, boil, condense or sublimate
their mass is conserved and that these physical changes differ from some chemical changes because the material recovers its original properties if the change is reversed.
what is specific heat capacity
the amount of energy needed to change the temperature of 1kg of the substance by 1*C. Different substances have different specific heat capacities, eg water- 4181 J/kg whereas oxygen is 918 J/kg
what is specific latent heat capacity
How much heat energy is needed to change state of 1kg of a substance. It takes more energy to evaporate 1kg of a substance than it does to melt 1kg of the same substance.
what is the change in thermal energy equation
changing temperature equation
mass x specific latent heat capacity x change in temperature
what is the thermal energy for a change of state equation
changing state equation
Q= mass x specific latent heat
explain the pressure of gas
for gases, the kinetic theory model explains that gas pressure is caused by the collisions between he particles and their container. This is called outwards pressure and is usually greater than normal atmospheric pressure outside the container
describe the term absolute zero
There is no upper limit, but the lowest temperature possible is -273*C. Almost all matter is solid and the vibrations of particles are very small. The temperature cannot go any lower. The theoretical temperature at which particles would stop moving is called absolute zero.
how to convert between kelvin and celsius scales
C—-K = + 273
K—-C = -273
explain pressure of gas on container walls
The effect of collisions with the container is to produce a net force acting on the container walls. This net force acts at right angles to the container walls, which is detected as gas pressure. This pressure can be measured using a pressure gauge
What is Boyle’s law
decreasing the volume of a gas increases the pressure of the gas. Because the volume has decreased, the particles will collide more frequently with the walls of the container. Each time they collide with the walls they exert a force on them. More collisions means more force so the pressure will increase.
why is pressure of a gas inversely proportional to its volume
when volume decreases the pressure increases
what equation would we use to calculate pressure or volume for gases of fixed mass at constant temperatures
P1 x V1 = P2 x V2
explain why doing work on a gas can increase its temperature, including a bicycle pump
A change in gas volume will cause a change in pressure. For example, the pressure increases as you pump up a bike tyre. More gas particles get squashed into the tyre, so more of them collide with the walls of the tyre each second.
