particle model of matter Flashcards
Describe the features of the particle model for a solid.
solid
- strong forces of attraction between particles
- fixed, regular pattern of particles
- particles vibrate in fixed positions
Describe the features of the particle model for a liquid.
liquid
- weaker forces of attraction between particles
- particles are close to each other, but in an irregular pattern so they have enough room so slide over each other
- particles move in random directions at low speeds
Describe the features of the particle model for a gas.
gas
- near to no forces of attraction between particles
- particles have the most energy (kinetic)
- particles are free to move in random directions at high speeds; constant random motion
What is density?
Density is the mass of an object that occupies 1m^3. The more particles in a given volume, the higher the density.
How do you calculate density?
density (kg/m^3) = mass (kg) / volume (m^3)
What is internal energy?
Internal energy is the total energy stored in a system by the particles. It is the sum of kinetic energy and potential energy.
What is potential energy? (in terms of particles)
Potential energy is the strength of the intermolecular forces, or how far apart the particles are.
What happens to the mass of an object during changes of state?
During changes of state, the mass is conserved; there are only physical changes, no chemical changes.
What is it called when a solid immediately changes state to a gas?
When a solid changes state directly to a gas, it is called sublimation.
How does heating an object affect the internal energy?
Heating an object increases the internal energy. The kinetic energy is increased during heating and potential energy is increased during changes of state.
What happens to the particles and temperature when melting occurs?
melting
- solid to liquid
- potential energy increases (as it is a change of state)
- kinetic energy stays the same
- internal energy increases
- temperature of substance stays the same
What happens to the particles and temperature when a liquid is heated?
heating liquid
- not a change of state
- potential energy stays the same
- kinetic energy increases
- internal energy increases
- temperature of substance increases
What happens to the particles and temperature when a liquid is boiled?
boiling liquid
- liquid to gas
- potential energy increases (as it is a change of state)
- kinetic energy stays the same
- internal energy increases
- temperature of substance stays the same
What happens to the particles and temperature when a gas is cooled?
cooled gas
- not a change of state
- potential energy stays the same
- kinetic energy decreases
- internal energy decreases
- temperature of substance decreases
What happens to the particles and temperature when condensation occurs?
condensation
- gas to liquid
- potential energy decreases (as it is a change of state)
- kinetic energy stays the same
- internal energy decreases
- temperature of substance stays the same
What happens to the particles and temperature when a liquid is cooled?
cooled liquid
- not a change of state
- potential energy stays the same
- kinetic energy decreases
- internal energy decreases
- temperature of substance decreases
What happens to the particles and temperature when freezing occurs?
freezing
- liquid to solid
- potential energy decreases (as it is a change of state)
- kinetic energy stays the same
- internal energy decreases
- temperature of substance stays the same
What is specific latent heat? Give the units.
Specific latent heat is the energy required to change the state of 1kg of a substance without raising the temperature. It is given in J/kg.
What is specific latent heat of fusion?
Specific latent heat of fusion is the energy required to change the state of 1kg of a solid to a liquid without raising the temperature. It is given in J/kg.
What is specific latent heat of vaporisation?
Specific latent heat of vaporisation is the energy required to change the state of 1kg of a liquid to a gas without raising the temperature. It is given in J/kg.
How does temperature relate to the particle motion in gases?
As the temperature increases, the particles have more energy transferred to their kinetic stores, so there is an increase in speed in a constant, random motion.
What is the pressure of a gas due to?
The pressure of a gas is due to the particles colliding with the walls of the container and each other.
How can the pressure of a gas be increased?
The pressure of a gas can be increased by increasing the number of collisions (so decrease the volume of the container) or by increasing the energy of collisions (so increase the temperature).
Give the equation that links the pressure in gases and volume.
pressure (Pa) x volume (m^3) = a constant number (if the temperature is constant)
In which direction is the pressure in gases exerted?
Particle collisions in gases cause a force at right angles to the walls of the container.
What effect does doing work on a gas have? Why?
Doing work on a gas increases the internal energy as the force that you exert is transferred to the particles stores, increasing the temperature as well.
