P1.2 - Change of State Flashcards
define density
mass per unit volume
what is the equation for density?
density = mass(kg)/ volume (m3)
what three factors does density depend on?
- mass of material
- particle arrangement
- volume
explain why the density of a substance in that the solid state is greater than the density of the same substance in the liquid state
- there are more particles in the same volume (solid)
- and so the mass is greater
in a liquid, there are less particles in the same volume
so the mass is less
(leading to a higher density)
why do substances in different matters have different densities?
they have different arrangement of particles
define temperature
the average kinetic energy per particles
is temperature a measure of heat energy?
no, particles do not know heat energy, only kinetic
why does your hand not burn if a spark lands on you?
- the mass of the sparkler is very small
- the total energy stored by all the particles is small
- energy is so little, does not burn you
what does the energy in a thermal store depend on?
- the arrangement of the particles
- how fast they are vibrating or moving
what does the energy needed to raise the temperature of an object depend on?
- type of material
- the mass of the material
- temp rise
what is specific latent heat?
the energy transferred when 1kg of a substance changes state
what equation is required to calculate the change in thermal energy?
mass (kg) x specific heat capacity (j/kg C) x change in temperature (C)
what does specific heat capacity show?
the amount of energy needed to increase the temperature of 1kg of the substance by 1oC
why is water good to use in radiators?
because it has a high specific heat capacity, making it resistant to temperature change (so would have a lot of energy to transfer)
- almost 4200J/kg
why are saucepans made with low specific heat capacities?
- as they need to heat up quickly to heat the food
where does the energy from tropical storms come from?
- water vapour condensing and transferring energy to its surroundings
explain why there is no temperature increase while water is boiling
- energy transferred is used to break attractive forces between the water molecules
- internal energy is increasing but temp is not
what is the specific latent heat of fusion?
(melting)
- the energy transferred when 1kg of a substance changes from the solid state to the liquid state (or vise versa)
WITHOUT CHANGING TEMPERATURE
what is the specific latent heat of vaporisation?
the energy transferred when 1kg of a substance changes from liquid to gas WITHOUT CHANGING TEMPERATURE
what is the equation to calculate the thermal store for a change in state?
energy store (J) = mass (kg) x specific latent heat (J/kg)
what are the similarities and differences between specific latent heat and specific heat capacity?
- they both involve energy changes for 1kg of a substance
- latent heat is about change in state
- heat capacity is about change of temperature
what is the law of displacement?
an object completely submerged in a fluid will replace an amount of fluid of its own volume
what is the force that keeps an object afloat?
upthrust
what is the equation to calculate specific heat capacity?
change in internal energy / mass x change in temperature
