Flashcards in States of Matter Deck (23):
Properties of a solid:
- strong forces hold them in a fixed lattice
- keep definite shape and volume
- don't have much energy
Properties of a liquid:
- some force keeps them linked but free to move
- don't keep definite shape (fill the container)
- keep same volume
- constantly moving in a random motion
Properties of a gas:
- no force of attraction
- no definite shape or volume
- bounce around and exert pressure
- more energy than other two
- constant movement in random motion
How is a solid converted straight to a gas?
SUBLIMING: changes directly into a vapour
What is the difference between chemical reactions physical reactions?
Chemical reactions are irreversible.
What is a pure substance?
A substance with only one element or compound.
How do you test for purity using melting points?
A pure substance will have a sharp melting point, whereas a mixture will have a range of melting points.
What is simple distillation?
A technique used to separate a liquid from a solid.
This is done by heating seawater in a flask and collecting the distilled water from a condenser.
What is fractional distillation?
A technique used to separate a mixture of different liquids. This is done by heating it up to each boiling point and separating them out one by one, starting with the lowest boiling point.
What is filtration?
A technique used to separate insoluble solid from a liquid. This is done by filtering the sediments out with filter paper and collecting the liquid in a flask.
What is crystallisation?
A technique used to separate soluble solid from a solution. This is done by evaporating water off to leave salt behind, which then crystallises once it cools down.
What is chromatography?
A method used to separate a mixture of soluble substances.
What is the mobile phase in chromatography?
Molecules can move (in a liquid or gas)
What is the stationary phase in chromatography?
Molecules can't move (solid)
What does the time a molecule spends at each phase show?
- solubility in the solvent
- their attraction to the stationary phase
How do you calculate Rf values?
Rf = distance travelled by solute / distance travelled by solvent
What is potable water?
Water that is safe for consumption.
Give 3 example of SURFACE water:
Give an example of GROUND water:
an aquifer (rocks that trap water unerground)
Give an example of WASTE water:
contaminated water; microbe infected.
How is water purified in treatment plants?
1) FILTRATION - get rid of sediments
2) SEDIMENTATION - iron/aluminium sulfate clumps small particles together to remove them
3) CHLORINATION - bubble gas through; kills microbes
Why do people avoid distilling sea water?
It is very expensive as it requires so much energy