section 1 ABC Flashcards
need to practice solubility curves
what are the three states of matter?
solid, liquid, gas
what does each state depend on? what does this factor depend on?
how strong the forces of attraction are between the particles of the material. this depends on material, temperature, pressure
describe the arrangement of forces within a solid.
- in solids, there are strong forces of attraction between particles which hold them close together in fixed positions to form very regular lattice arrangments
- the particles don’t move from their positions, so all solids keep a definite shape and volume, and don’t flow like liquids
- the particles vibrate more about their positions and the hotter the solid becomes, the more they vibrate (causing the solids to expand slightly when heated)
describe the arrangement of forces within a liquid.
in liquids, there is a weak force of attraction between the particles. they’re randomly arranged and free to move past each other, but they tend to stick closely together
2. liquids have a definite volume but don’t keep a definite shape and will flow to fill the bottom of a container
3. the particles are constantly moving with random motion. the hotter the liquid gets, the faster they move. this causes the liquid to expand lightly when heated
describe the arrangement of forces within a gas.
- in gases, the forces of attraction between particles are very weak and they’re free to move and are far apart. the particles in gases travel in straight lines.
- gases don’t keep a definite volume or shape and will always fill any container
- the particles move constantly in random motion. the hotter the gas gets, the faster they move. Gases either expand when heated or their pressure increases
what is the name for a gas going to a liquid?
condensing (condensation)
name for liquid to gas?
evaporation
liquid to solid name?
freezing
solid to liquid name?
melting
solid to gas name?
sublimation (subliming)
what happens if a solid is heated?
When a solid is heated, its particles gain more energy.
This makes the particles vibrate more (aka faster), which weakens the forces that hold the solid together. this makes the solid expand
at a certain temp, the particles have enough energy to break free from their positions as the forces of attraction are no longer strong enough to hold them together.
this is called melting and the solid turns into a liquid
why does energy have other be supplied when converting something from a solid to a liquid?
this is because the particles in a liquid have more kinetic energy than particles in a solid so energy has to be supplied in tho convert the solid into a liquid
what happens from solid to liquid?
the liquid is cooled. the particles will move around more slowly until they move so slowly that the forces of attraction between them will hold them in a fixed position and the particles pack more closely together in a solid.
the liquid freezes, forming a solid.
the temp at which this occurs it the freezing point
what happens when a liquid is heated?
the particles get more energy. this makes them move faster which weakens and breaks the bonds holding the liquid together
at a certain temp, the particles have enough energy to break their bonds.
at this point, the liquid is evaporating the the liquid turns into a gas
what is boiling?
it occurs when a liquid is heated so strongly that the particles are moving fast enough to overcome all forces of attraction between them
the stronger the forces of attraction between the particles, the higher the boiling point of the liquid.
this is because more energy is needed to overcome these forces of attraction
what is evaporation?
in any liquid or gas, the average speed of particles varies with temp. but at each temp, some particles will be moving faster than the average particle and others more slowly.
some very fast particles at the surface of the liquid will have enough energy to overcome the forces of attraction between the particles and they will break away to form a gas.
note: here you don’t see any bubbling, it just slowly disappears. it the liquid is in a container,so evaporation and condensation will occur because the particles collide with the surface of the liquid aswell
when can evaporation occur?
at any temp. e.g., puddles evaporated at 5 degrees not at their boiling point which is 100 degrees
what is gas to solid called?
deposition
how would you be able to tell the physical state of a substance by knowing its boiling/melting point?
below melting - solid
above melting - liquid
below boiling - liquid
above boiling - gas
what is diffusion?
Diffusion is the random movement of particles from a region of their high concentration to a region of their low concentration down the concentration gradient.
FORMAL DEFINITION:
Diffusion is the spreading out of particles form where they are at a high concentration to where they are at a low concentration
describe a practical to see diffusion.
get a beaker of water and place potassium manganate (VII) at the bottom
- the purple colour slowly spreads to fill the beaker
- the particles are diffusing out among the water particles
- it is the random motion of particles in a liquid that causes the purple colour to eventually spread out through water
note this can take days because the particles in a liquid move more slowly than particles in a gas
describe a practical to show that particles of different gases travel at different speeds
- aqueous ammonia (NH3) gives off ammonia gas. HCl gives off hydrogen chloride gas
- get a glass of tube and put a piece of cotton wool soaked in concentrated ammonia solution on one end and a source of cotton wool soaked in concentrated hydrochloric acid on the other end. close each side with a bung
- both particles diffuse along the tube
- a ring of solid ammonium chloride forms where they meet. this ring takes time to form and appears closer to the hydrochloric acid end.
- this is because ammonia particles are lighter and therefore move faster
and therefore travel further in the same amount of time
how else can you show the diffusion of a gas?
- you can put bromine in the first half od a glass jar. bromine is a brown strongly smelling gas
- fill the other half with air and separate the gases with a glass plate
- when the remove the plate, you’ll see the brown bromine gas slowly diffuse through the air
- the random motion means that the bromine will eventually diffuse right through the air
what is a solute?
a substance that dissolves in a solvent
what is a solvent?
the liquid in which a solute dissolves.
what is a solution?
the mixture of the dissolved solute and the solvent it is dissolved in
what is a saturated solution?
A saturated solution is one in which no more solid can dissolve in the liquid at a given temperature.
(must be some undissolved solid present to make it saturated)
what happens in a solution?
the attractive forces in the solute are being broken. at the same time, new attractive forces are being formed between the solvent particles and the solute particles.