sc1 - 2, states of matter (paper 1) Flashcards
define compound
two or more different elements held together by different bonds (always found in the same proportions)
define mixture
two or more substances not chemically bonded together (as they haven’t reacted)
what is filtration used for
to separate an insoluble solid from a liquid
what is crystallisation for
to seperate a soluble solid from a liquid
what is a solvent
a liquid that dissolves substances
steps of chomotography paper practical
- chomotography paper with pencil lines on the bottom and put dotted lines of the pen we want to use
- lower it into a solvent which makes it way up the paper and dissolves ink in the two coloured dots which are carried up
what is the stationary phase in the chomotography paper practical
paper as it doesn’t move
what is the mobile phase in the chomotography paper practical
solvent as it moves
why does chomotography paper practical work
because each chemical mixture will be attracted to the stationary phase to a different extent
what is simple distillation used for
- separate a solvent from a solution
- if we want to keep the liquid
what is fractional distillation used for
- separate a mixture of miscible liquids
how to calculate the Rf
distance by spot / distance by solvent
what happens in paper chomotography
- each soluble substance in the mixture forms bonds with the two phases
- substances that form stronger attractive forces with the stationary or mobile phase move different lengths
in paper chomotography:
if the subtance moves further, is it more attracted to the mobile or stationary phase?
mobile phase
in paper chomotography:
if the subtance moves less, is it more attracted to the mobile or stationary phase?
stationary phase
how can we make the Rf more accurate
using a longer or different paper
what can a chromatogram be used for
- distinguish pure and impure inks
- identify a substance by comparing
what does a pure ink produce in paper chromatography
only one spot
what does an impure ink produce in paper chromatography
multiple spots
steps in simple distillation
- solution is heated and the solvent boils
- solvent va[our passes into the condenser
- vapour cools and condenses back to the liquid state in a seperate beaker/flask
steps in fractional distillation
- the mixture is heated and hot vapour rises up the fractionating column
- the liquid with the higher boiling point condenses when it hits the cools urface and drips back
- the liquid with the lowest boiling point has it’s vapour reach the condenser first
how does a condenser keep cool
it has two tubes keeping cold water running in and out
describe the tempurature gradient in a fractionating column
hottest at the bottom, coldest at the top
define molecule
two or more atoms, held together by chemical bonds, which can contain different elements
steps in crystallisation
- place the solution in an evaporating dish and slowly heat
- once some of the solvent has evaporated and crystals start forming, stop heating it
- leave it to cool
- more crystals start to form, as solids are less soluble at colder tempuratures
- filter them
- dry them in an air oven or warm place
steps in evaporation
- heat solution in an evaporating dish
- solvent starts evaporating and the remaining solution becomes more concentrated, forming crystals
con of evaporation
it may be quick and easy but some solids may decompose when heated (thermal decomposition)
steps in filtration
- use a filter paper and funnel
- filter paper has small holes that allow the liquid to pass through, but not the solid
what is filtration used for
to seperate an insoluble salt from a liquid
what happens in sublimation
solid to gas
what happens in deposition
gas to solid
what happens during a state change
- energy is transferred to or from the particles
- the arrangement of particles change
- the movement of particles change
what is the order of different states in increasing energy stores
solid, liquid, gas
what is the order of different states in decreasing energy stores
gas, liquid, solid
true or false: mixtures have a more varied melting/boiling point than a single element, which is more sharp
true
what are the stages of making water potable
sedimentation, filtration, chlorination
define potable
safe to drink
what must potable water have
low levels of contaminating substabces and microbes
explain why tapn water is potable but not pure
it contains dissolved salts and chlorine which is more than one element
why is using distillation by boiling and condensing for sea water hard
it’s expensive
what is sedimentation
large insoluble particles sink to the bottom of a tank
what is filtration
small insoluble particles are removed by filtering through beds of sand
what is chlorination
chlorine gas is bubbles from the water to kill microbes
