Particle Model of Matter Flashcards
What is the equation for density? What are its units?
density = mass / volume
units are: kg/m^3 or g/cm^3
What is the arrangement and closeness of particles in a solid, liquid and gas?
Solids:
Regular arrangement
Paricles are very close together
Liquids:
Random arrangement
Particles are close together - mostly touching, and there’s no space for another particle
Gases:
Random arrangement
Particles are far apart (large compared to others), not touching; plenty of space between them
What is the motion, forces and properties of particles in a solid, liquid and gas?
Solids:
Motion - vibrating around fixed positions
Forces - strong
Properties - rigid, incompressible, dense
Liquid:
Motion - moving a bit + still touching other particles (but not vibrating)
Forces - less strong/weak
Propertires - not rigid, can flow; incompressible; less dense
Gas:
Motion - random directions at a range of speeds; colliding with each other and container walls (not vibrating)
Forces - none or very weak
Properties - fill their container; compressible; very low density
Draw a model of a solid, liquid and a gas.
Required practical 5.
What is the difference between a chemical change and a physical change?
In a physical change, the material recovers its physical properties if the change is reversed.
What are the different changes of state?
Solid to liquid: melting
Liquid to gas: boiling
Gas to liquid: condensing
Liquid to solid: freezing
Solid to gas: subliming
Gas to solid: depostion
True or false - boiling 1kg of water produces 1kg of steam.
TRUE! Boiling 1kg of water produces 1kg of steam, a gas. Gases have mass just like liquids and solids - if you boil water and none of it is left in the kettle, the water particles have not been destroyed.
Is there a difference between “freezing point” and “melting point”?
No - for example, at 0 degrees, water can exist as either a solid or liquid.
Does freezing mean being cold?
FREEZING DOES NOT MEAN COLD - wax freezes at 80 degrees, which we don’t consider cold.
What is internal energy?
Energy is stored in a system by the particles (atoms and molecules) that make up the system. This is called internal energy.
Internal energy is the total kinetic and potential energy of all the particles (atoms and molecules) that make up a system.
How does heating change the energy stored within the system?
Heating changes the energy stored in a system by increasing the energy of the particles that make up that system. This either raises the temperature of the system (increases kinetic energy - energy of random thermal motion) or produces a change of state (increases potential energy).W
What does the change in temperature of a system depend on?
If the temperature of a system increases, the increase in temperature depends on: the mass of the substance heated
the type of material
the energy input to the system
What equation links to temperature changes in a system?
changes in thermal energy = mass * specific heat capacity * temperature change
What is the specific heat capacity of a substance?
Specific heat capacity of a substance is the amount of energy required to raise the temperature of 1kg of a substance by 1 degree celsius
What is latent heat?
Latent heat is the energy needed for a substance to change state. When a change of state occurs, the energy supplied changes the energy stored (internal energy) but not the temperature.
What is the specific latent heat of Fusion?
The Specific Latent Heat of Fusion is the energy required to change 1kg of a substancne from the solid state to the liquid state without changing its temperature.
What is the specific latent heat of Vaporisation?
Specific Latent Heat of Vaporisation is the energy required to change 1kg of a substance from a liquid state to a gaseous state without changing its temperature.
What is the equation for the energy required to melt and boil?
Energy required to melt:
E = M x L
energy for a change in state = mass x specific latent heat of fusion
Energy required to boil:
E = M x L
energy for a change in state = mass x specifc latent heat of vaporisation
What happens to temperature of a substance as energy increases? (heating curve)
As energy of a solid increases, the vibration KE of the particles increases. Once a certain temperature is reached, the solid melts, as bonds between the particles in a solid are melting. KE is not changing due to no change in temperature.
Once the entire substance is a liquid, temperature increases again as there is an increased KE of particles.
When a certain temperature is reached, the liquid vaporises. Whilst the substance is a mixture of liquids and gases, the bonds between the particles are being broken in the liquid. Energy is still being gained, though it’s not KE (it’s PE).
Once the substance is entirely a gas, the temperature increases again as there is an increased KE of particles.
Energy (or time) has been increasing the entire time.
What happens to internal energy, thermal energy and potential energy as energy in a substance increases?
Temperature: increases/rises when it’s not changing state.
Internal energy: always rises as it is the total of KE + PE
Thermal energy: rises when it’s not changing state
Potential energy: Potential energy rises when it is changing state.
Potential energy is due to breaking and making bonds, kinetic energy is due to random thermal motion
What is a cooling curve?
The opposite of a heating curve
What is the difference between specific heat capacity and specific latent heat?
Specifc heat capacity determines the energy needed to change temperature, whilst specific latent heat is the energy needed to change state.
What is temperature?
Temperature measures the average kinetic energy per particle of random thermal motion of the particle in an object (aka the average KE of the molecules)
