particle model of matter Flashcards
what is the definition of density
the mass per unit volume of material
state the different states of matter in order (Least to most) of density of atoms
least dense: gas
middle: liquid
most dense: solid
describe the particle arrangement of a solid
tightly packed in a regular arrangement
particles can only vibrate on the spot
describe the particle arrangement of a liquid
close together
but with an irregular arrangement
they can flow over each other
describe the particle arrangement of a gas
separated, with no regular movement
particles can move freely
what is always conserved when a substance undergoes a change of state
mass
how does a chance of state differ from a chemical change
in a change of state, the material can return to having its previous properties if the change is reversed
what is sublimation
when a solid changes into a gas without passing through a liquid state
what is evaporation
when a liquid changes into a gas state
what is the opposite of evaporation
condensation
what is the internal energy of a substance
the energy stored by the particles
the sum of the total kinetic and potential energies that make up the system
how does heating affect the energy of a substance
heating transfers energy to the substance
it increases the energy of the particles that make up the substance
what 2 things can heating a substance do
- raise the temp
- change the state of the substance
what 3 factors determine the temp change of a system
- mass of substance being heated
- type of material
- energy inputted into the system
define specific heat capacity
the amount of energy needed to increase the temp of 1kg of a substance by 1 degrees
describe how the internal energy and temperature of a substance Changs when a change of state occurs
the internal energy of the substance will be increased or decreased
the temperature of the substance will remain constant
define specific latent heat
the amount of energy needed to change the state of 1kg of a substance with no change in temperature
state the equation for the energy required to change state
energy to change state = mass x specific latent heat
what is specific latent heat of fusion?
the energy required to change 1kg of a substance from solid state to liquid state without a change in temperature
what is the specific latent heat of vaporisation
the energy required to change 1kg of a substance from a liquid state to a gas state (vapour) without a change in temperature
describe the motion of molecules in a gas
they are in a constant random motion
what factors affects the average kinetic energy of gas molecules
the temperature of the substance
the higher the temperature the higher the average kinetic energy of the molecules
what effect does increasing temperature have on the pressure of a gas when held at a constant volume?
pressure of the gas will increase as temperature increases
why does pressure increase as temperature increases (constant volume)
kinetic energy of molecules increase
collisions between molecules becomes more frequent
greater rate of change of momentum
greater force and therefore pressure
describe the force that the pressure of a gas exerts on the walls of its container
the net force at right angles to the containers surface
the force increases as pressure increases
explain how increasing the volume of a gas results in a decrease of pressure
- molecules become more spread out and so time between collisions increase
- this reduces rate of collisions
- rate of change of momentum decreases, and so force exerted on container decreases, resulting in a lower pressure
what can be said about the product of pressure and volume for a fixed mass of gas at a constant temp?
being constant
what is the unit used for pressure
pascal
what increases when you do work on a gas?
- the internal energy of the gad
- this can also lead to an increase of temperature
why does the temp of air inside a bike pump increase when it is pumped?
- work is done on a gas when it is compressed
- doing work on a gas increases its internal energy, so also increases the average kinetic energy of the molecules
- temp increases with an increase of average kinetic energy
