Topic 3 Paricle Model Of Matter Flashcards
Why do solids usually have a very high density?
Particles are packed closely together-lot of mass for their volume
Why do liquids usually have a high density?
Particles are close together-lot of mass for their volume
Why do gases have a low density?
Particles are very far apart-small mass for their volume
What is internal energy?
The total kinetic energy and potential energy of all the particles that make up a system
What is sublimation?
When a solid turns directly to a gas
What does the density of an object depend on?
What it’s made of and how it’s particles are arranged
How are the particles in a dense material arranged?
Packed tightly together
Why do gases usually have low densities?
Almost no forces of attraction between particles (particles not close together)
What happens if you reverse a change of state?
Substance return to its original form and original properties
What is conserved in a change of state?
Mass
What is internal energy?
Total kinetic energy and potential energy of all particles that make up system
How does heating change the energy stored within a system?
Transfers energy to its particles, gain energy in kinetic stores and move faster, increases internal energy
What are the 2 possible outcomes of heating a system?
Raises temperature or change in state
What are the 3 things that a change in temperature of a system depends on?
Mass of substance heated
What it’s made of (specific heat capacity)
Energy input
When will a change in state occur?
Particles have enough energy in kinetic stores to break bonds
What is the energy needed to change the state of a substance called?
Latent heat
What is specific latent heat of a substance?
Amount of energy needed to change state of 1kg of substance without changing its temp
What is specific latent heat for cooling?
Energy released by change in state
What is the specific latent heat different for?
Different materials and for changing between different states
What is the specific latent heat of changing between a solid and a liquid (melting or freezing) called?
Specific latent heat of fusion
What is the specific latent heat for changing between a liquid and a gas (evaporating/boiling/condensing) called?
Specific latent heat of vaporisation
What is the formula for specific latent heat?
Energy = mass x SLH
What are the units for specific latent heat?
J/kg
What is happening when a substance is melting or boiling?
Increased internal energy used for breaking bonds between particles (not raising temp)
What is happening when a substance is condensing or freezing?
Bonds forming between particles, releases energy, internal energy decreases
When a substance is condensing or freezing, what does the temperature not go down until?
All substance turned to liquid/solid
What happens if you increase the temperature of a gas?
Transfer energy to kinetic energy stores of particles, average speed of particles increases
What is the temperature of a gas related to?
Average energy in kinetic energy stores of particles
What do gas particles do when they collide with something?
exert a force- pressure
What is the outward gas pressure in a sealed container?
Total force exerted by all particles in gas on unit area of container walls
Why does increasing the temperature of a gas increase the pressure (if volume kept constant)?
Faster particles, more frequent collisions, increase in net force
What happens if the volume of a gas is increased and the temperature kept constant?
Particle more spread out, hit container walls less often, gas pressure decreases
What is the relationship between pressure and volume?
Inversely proportional
What is the relationship between pressure and volume for a gas of fixed mass at constant temperature?
pV = constant
What does the pressure of a gas cause?
Net outwards force at right angles to surface of its container
Why is there also a force on the outside of a container?
Pressure of gas around it
If a container can easily change its size what can a change in pressure cause?
Container to compress or expand due to overall force
What is an example of a container that can be compressed or expanded?
Helium balloon
What does doing work (transfer of energy by a force) on a gas do?
Increases its internal energy, increases its temperature
Why does doing work on a gas using a bike pump lead to an increase in temperature of the gas?
Gas applies pressure to plunger of pump, exerts force on it, work has to be done against force to push down plunger, transfers energy to kinetic stores gas particles
