particle model of matter Flashcards
What is density?
Mass per unit volume.
What is the equation for density?
Mass
———
Volume
Why do gases have the lowest density?
~Spacing between the atoms increase by x10
~As the particles have lots of energy to move
~This increases volume
~Which therefore decreases density
What stays the same when evaporating, melting, condensing and freezing?
Mass.
True or false? Are physical changes reversible?
True.
What is internal energy stored in?
Particles (atoms and molecules) within a system.
What are 2 examples of internal energy?
Kinetic energy and potential energy.
What does heating increase?
The internal energy.
What does internal energy do when heated?
Raises the temperature or produces a change of state.
What is specific heat capacity?
The amount of energy required to raise the temperature of 1kg of a substance by 1 degree.
What is the equation for specific heat capacity?
Change in thermal energy= mass x specific heat capacity x temperature change.
What is specific latent heat?
The amount of energy required to change the state of 1kg of a substance without a change in temperature.
What must the substance be before specific latent heat occurs?
At the right temperature to change state first.
What is specific latent heat of fusion?
The energy to melt/freeze.
What is specific latent heat of vaporisation?
The energy to boil/condense.
What is the equation for specific latent heat?
Energy for a change in state= mass x specific latent heat.
In melting and evaporating, energy is…
Absorbed.
In freezing and condensing, energy is…
Released.
What is sublimation?
When a sold goes straight to a gas eg. solid CO2.
The higher the temperature in pressure…
The greater the average kinetic energy as molecules move faster.
What happens when molecules collide with the walls of their container?
They exert a force on them.
What is gas pressure?
The total force exerted by all the molecules in the container of a unit area.
What is the pressure law?
Changing the temperature of a gas held at a constant volume changes the pressure exerted by the gas.
What can pressure changes do to a gas?
Compress or expand it.
What is Boyle’s Law?
Increasing the volume in which a gas is contained (at a constant temperature) can decrease pressure. (due to a reduced number of collisions per unit area)
What is the equation for work done using pressure?
Pressure x volume.
What is work done when increasing the pressure of a gas?
Compressing or expanding the gas (changing the volume).
What are 2 ways of increasing the pressure of a gas?
~Adding more particles to fixed volume
~Keepijg a fixed number or particles but for a smaller volume
