P6 Molecules And Matter Flashcards
Which two quantities do you need to measure to find the density of a solid or liquid?
mass and volume
What happens to the particles in a substance if its temperature is increased?
they move faster and the energy in their kinetic energy store increases
Why are changes of state physical changes?
no new substances are produced and the substance will have the same properties as before if the change
is reversed
Why is the mass of a substance conserved when it changes state?
the number of particles does not change
What is the internal energy of a substance?
the total kinetic energy and potential energy of all the particles in the substance
Why does a graph showing the change in temperature as a substance cools have a flat section when the substance is changing state?
the energy transferred during a change in state causes a change in the internal energy of the substance
What is the name given to the energy transferred when a substance changes state?
latent heat
What is the specific latent heat of a substance?
the energy required to change the state of one kilogram of that substance with no change in temperature
What is the specific latent heat of fusion of a substance?
the energy required to change one kilogram of the substance from solid to liquid at its melting point, without changing its temperature
What is the specific latent heat of vaporisation of a substance?
the energy required to change one kilogram of the substance from liquid to vapour at its boiling point, without changing its temperature
On a graph of temperature against time for a substance being heated up or cooled down, what do the flat (horizontal) sections show?
the time when the substance is changing state and the temperature is not changing
What property of a gas is related to the average kinetic energy of its particles?
temperature
What causes the pressure of a gas on a surface?
the force of the gas particles hitting the surface
Give two reasons why the pressure of a gas in a sealed container increases if its temperature is increased.
the molecules move faster so they hit the surfaces with more force and the number of impacts per second increases, so the total force of the impacts increases
Give two reasons why the temperature of a gas increases if it is compressed quickly.
the force applied to compress the gas results in work being done to the gas, and the energy gained by the gas is not transferred quickly enough to the surroundings
