chapter 4 Flashcards
types of separation techniques
- magnetic attraction
- filtration
- distillation
- chromatography
separating a mixture of magnetic and non-magnetic substances
magnetic attraction
how does magnetic attraction work
magnetic substance will be attracted to the magnet, which would be placed near the substances
application of magnetic attraction
scrapyards: iron attracted in scrapyards can be reused/recycled
separating a mixture of substances with different particle sizes/ soluble substance mixed with insoluble substance
filtration
filter paper characteristic
has pores of different sizes:
particles bigger than the pores will be retained as residue, particles smaller than the pores will be collected as filtrate
filtration technique example
a mixture of chalk and water is pored on a filter
components of filtration technique
- filter funnel lined with filter paper
- container for the filtrate
filtering process example
- a mixture of chalk and water is poured into a filter funnel lined with filter paper, which acts as a sieve
- the pores of the filter paper allow water particles to pass through, but not chalk particles, which are bigger than the pores -> retained by the filter paper
- solid that is left on the filter paper: residue
- liquid that passes thorugh the filter paper: filtrate
application of filtration (tea)
a tea strainer that seperates tea leaves from the tea
- tea leaves remain in a tea strainer while the tea passes through the holes in the tea strainer
application of filtration (nose)
the hair the nostrils + mucus (thick liquid produced in the nose), help trap large solid particles in the air that we breather in
- prevents such particles from entering the lungs
obtaining a solute from a solution
evaporation
evaporation explained
the solvent changes from liquid to gas state at a much lower temperature than the solute. after the solvent evaporates, we will be left with the solute as residue
components of evaporation
- evaporating dish/ crucible
- wire gauze
- tripod stand
- bunsen burner
evaporation process example
- heat is applied to the salt solution in the crucible, speeding up the change of water into water vapour
- water changes state at a lower temperature than salt, thus evaporating and leaving salt as the residue
applications of evaporation
preserving food:
- as water is essential for the decomposition of food, removing water through evaporation allows the preservation of herbs, spices, dried small fishes (ikan billies) etc…
obtaining liquid from a mixture of substances with different boiling points
distillation
distillation explained
a mixture is boiled, and the substance with the lowest boiling will gain heat and evaporate to form vapour. the vapour will come in contact with the cooler surfaces in the condenser, lose heat contract and condense to become condensed vapour, which is collected.
components of distillation
- distillation flask
- boiling chips (smooth boiling)
- thermometer (mouth of the condenser)
- condenser
- receiving flask
- bunsen burner
distillation process explained
- salt solution is heated in the distillation flask until it starts to boil
- water gains heat and changes into steam which passes thorugh the condenser
- the condenser, with cold water running thorugh it, acts as a cold surface that the vapour loses heat to, and condenses into pure water (distillate)
distillation application (pure water)
obtaining pure water using a solar still
- two rocks clamp down a plastic sheet, in which a pebble is place on top of in the middle
- water form the ground start to gain heat and evaporate to form water vapour, which loses heat to the cool plastic sheet, and condenses to form pure water droplets, which drop downwards and into the cup due to the rock on top.
distillation application (perfume)
obtaining perfume:
- plant parts (eg: petals) are boiled in water
- vapour collected as the distillate is made into perfumes
separating a mixture of substances that dissolve to different extents in a solvent
chromatography
chromatography explained
- some substances are more soluble than others, which will travel longer distances form the starting point
- insoluble substances will remaind at the starting point
chromatography components:
- filter paper
- ink spot on paper
- on the drawing line (pencil drawn)
- water
chromatography process
- a drop of ink is placed near the bottom of the filter paper
- the paper strip is dipped into water (commonly the solvent)
- water travels up the filter paper with the substances in the ink
- substance X, the most soluble, travels the furthest distance
- substance Y, insoluble, remains at the starting point
application of chromatographys
- identify colours in dyes
- identify substance used in food products
sources of water in singapore
- imported water
- local catchment
- NEWater
- desalinated water
desalination of water
- pre-treated seawater is pumped through partially permeable membranes at high pressure
- membrane: thin piece of material with small pores
- allows water particles, but not salt particles, to pass through
conserve water
3Rs:
- reduce
- reuse
- recycle
