Particles up to level 6 Flashcards
Explain what density is
What is the equation for density
Density is the mass per unit volume of a substance. This means it tells us how packed together the particles are
The equation for density is:
How do you calculate the volume of a regular solid and use this to find the density?
To find the volume of a regular solid you need to measure the length, breadth and depth and multiply them together.
Then you find the mass on a set of mass scales and find the density by using the formula density = mass/volume
How do you measure the volume of an irregular solid and use this to find the density of the object?
To find the density of an irregular object you need to use a displacement can. You fill the can with water, drop the object into the water and measure the volume of water that comes out of the can.
You then measure the mass on a mass balance and use the equation density = mass/volume to find the density of the object.
What are the conditions requred for something to float?
For an objet to float it needs to be less dense than the liquid that it is in.
What are the properties of a solid
Fixed shape
Dense
Cannot be compressed
Hard
What are the properties of a liquid?
Can flow
Takes the shape of its container
Dense
Cannot be compressed
What are the properties of a gas?
Can flow
Low density
Takes the shape of its container
Easily compressed
What are the changes of state labelled A-F in this diagram
A = Freezing
B = Melting
C = condensing
D = Evaporating/boiling
E = Deposition
F = Sublimation
How are the particles arranged in a solid?
How do the particles relate to its properties?
The particles in a solid are arranged close together in a regular order and are attached by strong bonds
Solids cannot flow becuase the particles are held together by the bonds between them. It is dense becuase the particles are all touching.
How are the particles arrange in a liquid?
How does the particle arrangement relate to it’s function?
The particles in a liquid are arranged in an irregular pattern but they are still touching. They are held together by weak intermolecular bonds.
Becuase the particles can move past each other, a liquid can flow and take the shape of its container. It is dense and cannot be easily compressed because the particles are close together
How are the particles arranged in a gas?
Explain how the particle arrangment of a gas relates to its properties
The particles in a gas are arranged so that they are randomly placed and are very far apart
A gas can flow becuase the particles can move past each other, this means it also takes the shape of its container. Gasses are not dense because there are spaces between the particles and can be easiliy compressed becuase these spaces can be made smaller
What is internal energy?
|nternal energy is the total energy of the particles of a substance
What is internal kinetic energy?
How do we detect internal kinetic energy?
Internal kinetic energy is the movement energy of the particles in a substance
The internal kinetic energy of a substance determines its temperature. The higher the internal kinetic energy the higher the temperature
What is the internal potential energy of a substance?
How do you change internal potential energy?
Internal potential energy is the energy of the particles becuase of their position and arrangement
Particles have more internal potential energy when they are further apart, or more disorganised. When they change state from solid to liquid (melt) or from liquid to gas (boil/evaporate) they gain internal potential energy. When they change state from gas to liquid (condense) or from liquid to solid (freeze), they loose internal potential energy.
Define the term ‘melting point’
Melting point is the temperature at which a substance changes state between a solid and a liquid. If the temperature is above the melting point it is a liquid, and if the temperature is below the meltion point it is a solid.
Define the term ‘boiling point’
The boiling point is the temperature that the substance changes from a liquid to a gas. When a substance is below the boiling point it is a liquid and when it is above the boiling point it is a gas
What is ‘latent heat’?
How do you calculate the latent heat of a substance when it changes state?
Latent heat is the energy required to change state. While something is changing state it does not change its temperature. This is becuase the energy is transferring into or away form the internal potential energy store and not the internal kinetic energy store.
To calculate the latent heat you use this formula:
E = mL
E = energy (latent heat) (J - Joules)
m = mass (kg - kilograms)
L = specific latent heat (J/kg - Joules per kilogram)
There are two different types of latent heat. If something is melting or freezing you need to use the specific latent heat of fusion. If something is boiling or condensing you need to use the specific latent heat of vaporisation
What happens to the internal energy of a substance when it is heated?
When a substance is heated the internal energy increases.
In which changes of state does internal potential energy increase and in which changes of state does it decrease?
When a substance melts or boils the internal potential energy increases. This is becuase the particles get further apart.
When a substance freezes or condenses the internal potential energy decreases. This is becuase the particles get closer together.
Explain how you find the melting and boiling points of a substance from this graph?
To find the melting point of the substance you read the temperature where the graph is horizontal at point B (-60oC in the diagram)
To find the boiling point you read the temperature where the graph is horizontal at point D (60oC in the diagram)
For section A of the diagram explain:
(a) What you would see happening
(b) The change of energy that is occuring
(a) The substance is a solid and it’s temperature is rising
(b) The internal kinetic energy of the substance is increasing
For section B of the diagram explain:
(a) What you would see happening
(b) The change of energy that is occuring
(a) The substance is changing state. The temperature remains constant
(b) The internal potential energy of the substance is increasing
For section C of the diagram explain:
(a) What you would see happening
(b) The change of energy that is occuring
(a) The substance is a liquid and the temperature is increasing
(b) The internal kinetic energy of the substance is increasing
For section D of the diagram explain:
(a) What you would see happening
(b) The change of energy that is occuring
(a) The substance is boiling and the temperature remains constant
(b) The internal potential energy of the substance is increasing
For section E of the diagram explain:
(a) What you would see happening
(b) The change of energy that is occuring
(a) The substance is a gas and the temperature is increasing
(b) The internal kinetic energy is increasing
What are the energy changes of each body when a block of ice is placed in water?
Energy is transferred from the internal energy store of the water to the internal energy store of the block of ice
Initially this means that internal kinetic energy from the water is transferred to internal kinetic energy of the block: The ice warms up and the water cools down. After a while, however, the ice reaches the melting point and changes state into a liquid. At this point the temperature stops rising as energy from the internal kinetic energy store of the water is now being transferred into the internal potential energy store of the ice.
What happens to the pressure of a gas in a sealed container when it is heated?
When the gas is heated the temperature goes up, this causes the pressure to go up as the particles of the gas are colliding harder with the walls of the container
What causes gas pressure?
Gas pressure is caused by the particles in a gas colliding with the walls of the container they are in.
This produces a force on the wall of the container, and when this force is over an area then it is a pressure.
What happens to the motion of the particles in a gas when they are heated?
When a gas is heated the particles move about faster. This is becuase there is an increase in the internal kinetic energy of the gas.
Describe what Browian motion is
Brownian motion is the motion of particles in random directions and at random speeds because of collisions between the particles in a gas or liquid
Describe Boyles law
What is the equation for Boyles law?
Sketch a graph showing boyles law
Boyles law states that the pressure of a gas at a constant volume is inversely proportional to the temperature
The equation for Boyle’s law is:
P x V = constant
P = pressure (Pa - pascals)
V = Volume (m3 - Meters cubed)
The graph for Boyle’s law is:
What is the relationship between the temperature and the internal kinetic energy of a substance?
As internal kinetic energy increases the temperature of the gas increases
Describe what happens to the pressure of the gas that comes out of a spray can
When the gas comes out of the spray can it is no longer in a fixed container and is allowed to expand. This means that the pressure goes down becuase pressure is inversely proportional to volume.
Explain why the temperature of a gas increases when it is compressed quickly
When you compress a gas quickly you are using a force to push the particles towards each other. This speeds them up so the internal kinetic energy increases, which increases the temperature.
This energy transfer occurs becuase energy = force x distance
