p3 Flashcards
what kind of a change is a change of state
physical change
what changes when state changes
density and energy
what is internal energy
internal energy is the total energy a particle in a system has and is made up of potential and kinetic energy
what two things can happen when internal energy is increased
- temperature of a substance is raised
or - change of state produced
what is specific latent heat
specific latent heat is the amount of energy needed per kilogram of a substance to change from one state to another without changing its temperature
specific latent heat of _______ covers freezing and melting
fusion
specific latent heat of _______ covers evaporation and condensation
vaporisation
what is the equation for specific latent heat
specific latent heat = energy / mass
specific latent heat - L ( J/kg )
energy - E ( J )
mass - m ( kg )
what is pressure
pressure involves collisions between particles and walls of their container
how will increasing temperature affect the pressure exerted by a gas in a container? (4)
- particles gain kinetic energy
- force exerted by each particle on the walls is larger
- higher rate collisions between other particles and walls of container
- pressure increases
if temperature stays constant how do you work out pressure
pV = constant
p - pressure ( Pa )
V - volume ( m^3 )
explain why the pressure exerted by the helium inside a ballon would increase when temperature increases but mass and volume stays constant? (4)
- particles have a higher mean kinetic energy
- so increased number of collisions with walls of the balloon per second
- so greater forces are exerted in collisions between particles and balloon walls.
- so greater force exerted on the same area
explain how the internal energy of water changes as it is heated from 20°C to 25°C
- mean kinetic energy of particles increases
- which increases the internal energy of the water
a student measured the mass of boiling water that was turned into steam in five minutes.
explain how the student could use this information to estimate the power output of the bunsen burner in watts.
work out energy transferred to water using E = mL
power output = energy transferred/time
power output = mL / time
use a time of a 300 seconds
explain how the evaporation of a liquid causes the temperature of the remaining liquid to decrease (3)
- particles with more energy
- leave the surface of the liquid
- which reduces the average kinetic energy of the remaining particles
