Unit 2- seperating substances Flashcards
What is a mixture
The substance that is mixed together but not chemically combined
What is the meaning of saturated
No more of the solute will dissolve in it, at that temperature
What is the meaning of aqueous solution
A solution in water
How to increase solubility
Increase the temperature
How to check if a substance is pure
Check melting point and boiling point
What is a residue
the solid you obtain when u separate a solid from a liquid by filtering
What is a filtrate
the liquid obtained from filtration
What is a trough
a piece of laboratory apparatus used for collecting gases
Descibe how to obtain solid copper(ii) sulfate from copper(ii) sulfate solution
Heat the solution, until it is saturated.Drop a small amount of the solution on a cool glass, if crystal is formed then cool the saturated solution. After leaving it cool, remove the crystals by filtering.
When is fractional distillation used
separate a mixture of liquid. ( it makes use of their different melting point)
Why is fractionating column ( such as glass beads) used in fractional distillation of water and ethanol
water can evaporate at any temperature, without the fractionating column, ethanol that comes out from the condenser will not be pure.
If the substance is more soluble then will it travel up the chromatography more
yes
What is a formula to get Rf value
Distance moved by substance/ distance moved by solvent
Describe how to carry out paper chromatography
Place a spot of each solution along a line drawn in pencil on slotted chromatography paper. Place a suitable solvent in the bottom of a beaker. Roll the paper and place it in the beaker. Remove the paper when the solvent almost reached the top. Make a line in pencil on it, to show where the solvent reached. Put the paper in an oven to dry out. Then spray locating agent then heat the paper in the oven for 10 mins. Make a pencil dot at the centre of each spot. Get the Rf value and compare the value to the Rf table.
Why is locating agent used in chromatography
The substance can be colourless, but locating agents react with them to form a coloured products.
