Change of State Flashcards
what are the three states of matter?
solid
liquid
gas
(plasma - don’t need to know/use this one)
what is the arrangement of a solid?
strong forces of attraction hold the particles close together in a regular lattice
uniform, regular arrangement
don’t have much energy, so can oly vibrate about a fixed point
closely packed
strong bonds
can’t be compressed
what is the arrangement of a liquid?
weaker forces of attraction between the particles
irregular, random arrangement
must be touching
slide over each other
more free to move than a solid as they have more energy than solids
can be poured - can take shape of its container
can’t be compressed
what is the arrangement of a gas?
irregular, random arrangement
almost no forces of attractio between the particles
takes shape of its container
particles ofter collide with the walls of its container
particles free to move in any direction - have more energy than particles in liquids and solids
can be compressed
what happens when a solid is heated
this is melting
the particles/molecules gain even more kinetic energy which causes them to vibrate faster until they eventually overcome the strong forces existing between them in a solid state
the forces between the particles/molecules get weaker but they are not broken
the particles/molecules still touch but they have no fixed position
what happes when a liquid is heated
the particles/molecules gain even more kinetic energy which allows them to overcome the strong forces between them in a liquid state
the molecules seperate, have large speeds and experience weak forces
their motion is rapid and random in nature
their motion causes them to randomly collide with other molecules and their container which exerts a pressure
what is the equation for pressure?
pressure = force ÷ area
what happens to the motion of particles when they absorb kinetic energy?
particles vibrate more and more quickly
describe what happens to the vibration, kinetic energy and strong forces in a solid when it melts
particles absorb heat and gain kinetic energy
(thermal energy is converted into kinetic energy)
particles vibrate more and more quickly
the strong bonds start to weaken
the solid starts to lose its regular arrangement
complete this diagram
(note that solid to liquid red arrow should be going other way)
what is the motion of a molecule of gas?
(Brownian motion)
random movement
continuos movement
bump into each other and container
collisions = change indirection or speed of movement
how does gas exert pressure on the walls of its container?
pressure is the force acting per unit area
pressure is measured in N/m2
the particles collide together and against their container
when the particles collide they change direction or speed of movement
when particles collide with the walls of their container they exert a tiny force
greater frequency of collisions = greater pressure
what is the difference between evaportaing and boiling?
evaportaing can take place at tempratures below the boiling point
boiling takes place throughout the liquid at boiling point
what three things does thermal energy do?
it is converted into kinetic energy
it is used to increase the kinetic energy
it is used to break bonds
is melting exothermic or endothermic?
endothermic
is cooling exothermic or endothermic?
exothermic
why does a solid not heat up like x?
thermal energy is being used to break the bonds
what state is A and what is happening
solid
particles are vibrating more
what state is B and what is happening
melting
strong bonds being broken
what state is C and what is happening
liquid
particles are moving about more
what state is D and what is happening
boiling
bonds being broken
what state is E and what is happening
gas
particles are moving about more
what state is A and what is happening
liquid
particles are moving about more
what state is B and what is happening
freezing
strong bonds being made
what state is C and what is happening
solid
particles moving more
what state is D and what is happening
solid
no longer cooling
Is there a rise in temperature during a change in state when bonds?
no - even though energy enters or leaves the system
Particles in liquids move in … directions and at … speeds
Particles in liquids move in random directions and at slow speeds
Particles in gases move in … direction and at … speeds
Particles in gases move in random directions and at high speeds
What is evaporation?
evaporation is when particles escape from a liquid to become gas particles
Particles can evaporate from a liquid at temperatures that are muhc higher/lower than the liquid’s boiling point
Particles near the surface of a liquid can escape and become gas particles if:
… (2 things)
Particles can evaporate from a liquid at temperatures that are muhc lower than the liquid’s boiling point
Particles near the surface of a liquid can escape and become gas particles if:
the particles are travelling in the right direction to escape the liquid
the particles are travelling fast enough (they have enough kinetic energy) to overcome the atractive forces of the other particles in the liquid
Which particles (fast or slow) are most likely to evaporate from the liquid?
What does this so to the average speed of the remaining particles and the temperature of the liquid?
The fastest particles (with the most kinetic energy) are most likely to evaporate from the liquid - so when they do, the average speed and kinetic energy of the remaining particles decreases
This decrease in average particle energy means the temperature of the remaining liquid falls - the liquid cools
What happens when we excercise or get hot?
you sweat when you exercise or get hot
as the water from the sweat on your skin evaporates, it cools you down
