Topic 3- Density and states of matter Flashcards
What is density?
The measure of compactness of a substance
Describe the arrangement of particles in a solid
- strong forces of attraction hold particles close together
- fixed, regular arrangement
- Particles don’t move much and vibrate about fixed positions
Describe the arrangement of particles in a liquid
- Weaker forces of attraction between particles in a liquid
- Partices are close together but can move past eachother
- They move random directions at low speeds
Describe the arrangement of particles in a gas
- almost no forces of attraction between the particles
- more energy than liquids or solids
- free to move and travell in random directions at high speeds
What is the internal energy of a system?
The internal energy of a system is the total energy that particles have in their kinetic and potential energy stores.
Why are gasses compressable?
The particles in a gas are very spread out and therefore by compressing a gas you are simply reducing the distance between particles.
What is internal energy?
The sum of all the individual kinetic and potential energy stores of the particles.
When changing state, when does potential energy increase?
As particles become further apart (during changing states)
When changing state, when does kinetic energy increase?
As particles vibrate more / move faster (when the temperature increases)
What is temperature a measure of?
The average kinetic energy of the particles in a substance.
What is the average kinetic energy of a substance at zero Kelvin?
zero
What is 0 Kelvin in degrees Celsius?
-273°C
What is specific heat capacity?
Specific heat capacity is the amount of energy required to raise the temperature of one kilogram of a substance by 1°C.
What unit is used to measure specific heat capacity?
J / Kg / °C.
What is the equation for power?
Power = energy / time
What is the latent heat of fusion?
The latent heat of fusion is the energy required to change 1kg of a substance from a solid to a liquid without changing the temperature.
What is the latent heat of vaporisation?
The latent heat of vaporisation is the energy required to change 1kg of a substance from a liquid to a gas without changing the temperature.
What is the equation for latent heat?
Latent heat= Energy supplied to change state / mass
L = Q / M
What is the unit used to measure latent heat?
J/kg
What is the equation for pressure?
Pressure = Force / Area
P = F / A
What is the unit for pressure?
N/cm^2 or Pascals (N/m^2)
What is Pascals equal to?
N/m^2
What is the equation for density?
Density = mass / volume e = M / v
What is the unit for density?
Often given in g/cm^3 but needs to be in g/m^3 before using in other formula.
Explain what happens when a gas particle hits the walls of its container.
- Gas particle hits the wall of its container.
- It changes direction, therefore accelerates.
- Therefore the particle has had a force exerted on it by the container.
- Therefore by Newton III the particle exerts an equal and opposite force on the container.
- Therefore as P=F/A, a pressure is exerted on the container.
What does how high air pressure is, depend on?
Air pressure depends on the speed of the particles and the number of collisions per second (frequency of collisions.)
Why does the pressure of a gas increase when the temperature increases?
Temperature is the measure of kinetic energy of the particles. If the particles have more kinetic energy, speed increases causing more frequent collisions. The gas particles exert a greater force on the box because they exert greater forces in collisions therefore increasing pressure.
What is the equation for Boyle’s law?
Pressure = constant / volume (P=K/V)
Pressure and volume are inversely proportional-
- increasing volume will result in a decrease in pressure
- decreasing volume will result in an increase in pressure
What happens when you compress a gas?
- Compressing a gas causes you to do work on it (force to move a piston to push on the gas.)
- Work done = energy transferred to thermal store of gas.
What will happen to a baloon if the atmospheric pressure around the balloon decreases?
The balloon will expand until the pressure inside drops to the same as the atmospheric pressure.
