matter - structures and properties Flashcards
what does time measure
how long it takes for something to happen
SI unit for time
seconds
common units: min, hour
what does temperature measure
how hot or cold something is
SI unit for temperature
K (kelvin)
common units: celsius
what does length measure
the distance between 2 points
SI unit for length
(m)metre
common units: cm, km
what does mass measure
how much matter is present in a substance
instrument to measure mass
- electronic balance
- beam balance
SI unit for mass
(kg) kilograms
common units: grams, tonnes
1 tonnes =
1000kg = 1000000g
what does volume measure
how much space somthing occupies
SI unit for volume
(m³) cubic metre
common unit: cm³, dm³
how many dp for burette, pipette and volumetric flask
2
how many dp for measuring cylinder
1
where to read the volume
bottom of meniscus
criteria for gas collection
- solubility of water
- density of gas
how to collect gas
gas syringe
(collect small and accurate volumes of gas)
methods for collecting gas
- water displacement
- downward delivery
- upward delivery
criteria for using water displacement to collect gas
insoluble in water
criteria for using downward delivery when collecting gas
denser than surrounding air
criteria for using upward delivery when collecting gas
less dense than surrounding air
examples of how to dry gas
- concentrated sulfuric acid
- quicklime (calcium oxide)
- fused calcium chloride
types of mixtures
- solid-soild mixture
- solid-liquid mixture
- liquid-liquid mixture
how to separate solid-solid mixtures
- magnetic attraction
- sieving
- using suitable solvents
- sublimation
what is the purpose of using magnetic attraction
use magnet to separate magnetic solids from non-magnetic solids
what is the purpose of using a sieve
separate solids with different particle sizes
what is needed when using a sieve
a sieve with suitable pore size
what is the purpose of using suitable solvents
separate solid-solid mixtures in which only one of the solids is soluble in the solvent
how to use suitable solvent
add solvent to disolve one solid
what is the purpose of using sublimation
separate a substance that changes from the solid to gaseous state directly
substances that can sublime
- dry ice
- iodine
- ammonium chloride
how to separate solid-liquid mixture
- filtration
- evaporation to dryness
- crystallisation
- simple distillation
what is the purpose of using filtration
separate insoluble solids from liquids
working principle for filtration
- particle size
- pore size of filter paper
what is the filtrate
liquid that passes through the filter
what is residue
solid that remains on the filter
what is the purpose of crystallisation
used to obtain a pure solid from its saturated solution
what is saturated solution
no more solute can be dissolved
what is the difference between evaporation to dryness and crystallisation
- evaporation to dryness is heated until there is no more solvent
- crystallisation is heated until a saturated solution is formed
when to use evaporation to dryness
solid that does not decompose
when to use crystallisation
solid that decompose
purpose of simple distillation
used to separate a pure solvent from a solution
what is distillate
pure substance that is collected after distillation
position of thermometer bulb
junction before entering the condenser
function of condenser
cool and condense hot vapour into liquid
direction of water entering condenser
bottom in top out
purpose of boiling chips
ensure smooth boiling
how to separate liquid liquid mixtures
- separating funnel
- chromatography
- fractional distillisation
what is miscible liquid
liquids that can mix
(homogeneous mixture)
what is immiscible liquid
liquids that cannot mix
(heterogeneous mixture)
what separating technique can separate immiscible liquids
separating funnel
purpose of separating funnel
separate immiscible liquids with different density
what separating technique can separate miscible liquids
fractional distillation
purpose of fractional distillation
separate miscible liquids with different boiling points
what does fractional distillation have that simple distillation does not
- fractionating column
- glass beads
purpose of chromatography
separate a mixture of substances which have different solubilities in a given solvent
when to use locating agent
colourless samples
purpose of locating agents
locate the spots on the chromatogram by making it visible
explain what is meant by Rf value of a sample
Rf value of a substance is a measure of its solubility in the solvent
how to measure Rf value
distance travelled by solute/distance travelled by solvent
what are important things to take note of during chromatography
- starting line drawn in pencil
- solvent level below starting line
- sample spot should be small and not too close
why does starting line need to be drawn in pencil
insoluble in solvent and will not interfere with the results
why does the solvent level need to be below starting line
prevent sample from dissolving before separating
why does the sample spot have to be small and not too close
ensure clear separating and prevents overlap
what is the solvent front
the distance travelled by the solvent
the greatest the distance
- the larger the Rf value
- more soluble in solvent
test for purity
heat substance to melt/boil it, if melting/boiling point is fixed, it is pure substance
