particles Flashcards
what does soluble mean?
a substance that can dissolve
what does insoluble mean?
a substance that cannot dissolve
what is a solute?
a substance that dissolves (usually a solid)
what is a solvent?
a substance that the solute dissolves in (usually a liquid)
what does saturated mean?
a mixture in which no more solute can dissolve
what is a solution?
a mixture of a solvent and a solute
what is a suspention?
an insoluble solid in a liquid
what does dissociate mean?
particles separate and they are no longer touching
this usually happens when a substance dissolves
what is solubility measured in?
grams per 100 cm cubed
describe the relationship between solubility and temperature
when a solid dissolves, its particles dissociate. this process requires lots of energy due to the strong forces between particles
at higher temps, the forces are weaker, so MORE particles dissociate
higher temps = higher solubility
what happens to the solubility of gases when temp increases?
SOLUBILITY DECREASES
the particles spread out further at higher temps, as they spread out it is harder to remain dissolved in the liquid
what is the general method for measuring solubility?
- measure x amount of solvent in measuring cylinder
- add excess solid and allow to dissolve (heat to speed up, water evaporates and solubility increases)
- filter and collect residue (y)
- x - y = solubility
what is a second method of measuring solubility?
- record mass of conical flask (144.1g)
- measure 25cm cubed of water into the flask
- re record the mass (168.26g)
- add excess solid and leave it to dissolve
- use water bath to maintain temp at 20 degrees C
- filter mixture (water remains on filter paper)
what can distillation be used to separate?
any solid from a liquid
if the solid is insoluble filtering is much easier but soluble solids in liquids are harder
distillation is used when the solvent is required, for example desalination
when 2 liquids are mixed together, when can distillation also be used?
liquids are miscible (form one FASE)
liquids have different bpts
what is distillation with 2 liquids called?
fractional distillation
how are immiscible liquids separated?
using a separating funnel
how are miscible liquids separated?
fractional distillation (different boiling points=
chromatography (different solubilities)
describe the full method for chromatography
- place 2cm^3 of solvent in a beaker
- draw a pencil line 2.5cm from bottom of paper
- place one drop of mixture on base line
- stand paper in solvent and cover beaker
- leave until solvent is around 1cm^3 from top
- draw line to show solvent distance (solvent front)
- dry paper with hot plate
why do the components separate in chromatography?
due to the difference in attraction to solvent particles
if there is a stronger attraction (MORE SOLUBLE) the particles move further
how do you calculate retention factor for chromatography?
distance of component/distance of solvent
answer should be a decimal
what is the definition of diffusion?
the RANDOM MOVEMENT of particles that causes them to spread out and mix (with a NET movement from higher to lower concentration)
describe in detail the 4 steps of diffusion
- the particles in the solid dissociate and DISSOLVE in the water (only happens in solids)
- water particles and dissociated solid slide over each other and mix, occurs at surface of crystal
- the random movement of particles causes them to gradually spread out
- once “equally spread” the particles continue to move randomly but there is no change in NET movement
what are the 2 factors diffusion depends on?
temperature
size/mass of particles
