P3- Particle Model of Matter Flashcards
Describe the three states of matter?
Solid: strong forces of attraction hold particles together in a fixed, regular arrangement and particles can only vibrate around their positions. Density is generally the highest in this state as the particles are the closest together.
Liquid: weaker forces of attraction between particles- the particles are close together but can move past one another, and form irregular arrangements and have more energy than particles in solid and move in random directions at low speeds- less dense.
Gas: almost no forces of attraction between particles and they have more energy in liquids and solids and theyre free to move and travel in random directions at high speeds- less dense than liquids.
How to find density of a liquid?
1) Place a measuring cylinder on a balance and zero the balance.
2) Pour 10ml of liquid into meas cylinder and record liquid’s mass.
3) Pour another 10ml into the measuring cylinder, repeating the process until the cylinder is full and record the total vol and mass each time.
4) Use formulae- density= mass/vol
5) Take an average of calculated densities
What is internal energy?
Why is internal energy a total energy of KE and GPE?
What happens when the system is heated? What does it lead to?
Why does a change of state occur?
The internal energy of a system is the total energy that its particles have in their kinetic and potential energy stores
-Total internal energy because particles in a system vibrate or move around as they have energy in KE stores and they have energy in their PE stores due to their positions.
. Heating the system transfers energy to its particles as they gain energy in their KE stores and move faster, increasing internal energy. It leads to a change in temp or a change in state
-Change of state occurs if the substance is heated enough and the particles will have enough energy in the KE stores to break the bonds hoolding them together.
What’s happening when a substance is melting or boiling?
Energy is being put in which increases the internal energy but the energy is being used to break intermolecular bonds rather than raise the temperature, resulting in flat spots on the graph where energy is being transferred by heating but not being used to change the temp.
The temp only increases once all the intermolecular forces have overcome to change state.
What’s happening when a substance is condensing or freezing?
-Bonds are forming between particles which releases energy and that means internal energy decreases but the temp does not go down until all the substance have turned to liquid due to consensing or a solid from freezing.
Define specific latent heat?
slh between solid and liquid? slh for liquid to gas?
formulae?
the SLH of a substance is the amount of energy needed to change 1kg of it from one state to another without change in temp.
slh of fusion from a solid to a liquid.
slh of vaporization from a liquid to a gas.
energy= mass x slh
What happens if temp of a gas increases?
-Particles in a gas are constantly moving with random directions and speeds and if you increase the temp of a gas, transfer energy into the KE stores as the temp of a gas is related to the average energy in the KE stores of the particles in the gas. The higher the temp, higher the average speed.
How is pressure created in gas? What happens in a sealed container?
How is pressure increased?
What happens if temp is constant and volume is increased?
Formulae ^
As gas particles move in high speeds, they collide regularly which exerts a force on an object they collide with. In a sealed container, the outward gas pressure is the total force exerted by all of the particles in the gas on a unit area of the container walls.
Faster particles and more frequent collisions both lead to an increase in net force and so gas pressre. Increasing temp increases the speed and so the pressure.
Temp is constant and volume is increased, particles are more spread out and pressure decreases as they collide with the walls less frequently.
Pv= constant
How can a change in pressure cause a change in vol?
The pressure of a gas causes a net outwards force at right angles to the surface of its container. There is also a net force on the outside of the container due to the pressure of the gas around it. If the container can easily change it’s size( eg a balloon) than any changes in these pressures will cause the container to compress of expand, due to overall force.
What happens if a helium balloon is released?
It rises, atmospheric pressure decreases with height so the pressure outside the balloon decreases which causes the balloon to expand until the pressure inside drops to the same as atmospheric pressure.
How can gas temp be increased alternatively?
Givee an example?
Doing work on a gas increases its internal energy- increases temp
Doing work on a gas mechanically eg with a bike pump. The gas applies pressure to the plunger of the pump and so exerts a force on it. Work has to be done against the force to push down the plunger and this transfers energy to the KE stores of the gas particles, increasing its temp. If the pump is connected to a tyre, it will get warmer
