Topic 2 States Of Matter And Mixtures Flashcards
States of matter
There are three states: solid, liquid and gas
Solid- close together regular arrangement of particles
- the particles vibrate in fixed positions
- it has the least stored energy
Liquid- close together but random arrangement of particles
- the particles move around each other
Gas- far apart and random arrangement of particles
- the particles are fast in all directions
- most stored energy
What are the state changes?
Gas to liquid= condensing
Liquid to solid= freezing
Solid to liquid= melting
Liquid to gas= evaporating
Gas to solid= deposition
Solid to gas= sublimation
What are Pure substances and mixtures?
Mixtures are impure substances
Pure substances contains only one element or compound
Example:
Pure hydrogen contains only hydrogen molecules
Pure water contains only water molecules
What is distillation?
Simple distillation- separate a solvent from a solution
Method:
- solution is heated
- solvent boils
- solvent vapour passes into the condenser
- the vapour is cooled and condensed back to the liquid state
Fractional distillation- separate a liquid from a mixture of miscible liquids
Method:
- the mixture boils
- hot vapour rises up the fractionating column
- vapour condenses when it hits the cool surface of the column and drips back
- the fraction with the lowest boiling point reaches the top of the column first
- its vapour passes into the condenser
What is filtration?
You use filtration to separate an insoluble substance from a liquid or a solution.
To purify a liquid or a solution by removing solid impurities from it.
Filter paper- large enough to let water molecules and dissolved substances through
What is crystallisation?
You use crystallisation to produce solid crystals from a solution.
Method:
- the solution is heated to remove enough solvent to produce a saturated solution
- the saturated solution is allowed to cool
- crystals form in the solution
- the crystals are separated from the liquid and dried
What is paper chromatography?
Paper chromatography is used to separate mixtures of soluble substances
Two phases:
- stationary phase= a substance that doesn’t move
- mobile phase= a substance that moves through the stationary phase- the solvent
Rf= distance travelled by the spot/ distance travelled by the solvent
What is drinking water?
Potable water=
- low levels of contaminating substances
- low levels of microbes
Fresh water can come from reservoirs, lakes and rivers. It likely to obtain leaves, insoluble solids and microbes which can cause disease. The water must be treated to remove these.
Tap water is potable but it is not a pure substance. It contains:
- dissolved salts
- dissolved chlorine
What are the definitions for a particle and an atom?
Particle: a general name for an atom or a molecule of matter
Atom: the smallest part of an element, which can take part in chemical reactions
Describe a solid
Particles are arranged in a regular and ordered pattern, closely packed together
Vibrate in a fixed point
Low energy
Can’t compress
Fixed volume
Describe a liquid
Liquids are arranged randomly and closely packed together
Move randomly around each other
Medium energy
Fixed volume
Takes shape of a container
Cannot compress
Describe a gas
Gases are arranged with random and very little contact
Move quickly in all directions
High energy
Fills a container if sealed
Can be compressed
What does pure, solvent, solute, soluble and solution mean?
Pure: contains a single type of element or compound
Solvent: a liquid that something may dissolve in
Solute: a solid that may dissolve
Solution: a mixture of a solute in a solvent
Soluble: a substance that will dissolve
What does melting and boiling point mean?
Melting point: The temperature at which a substance turns from a solid to a liquid
Boiling point: the temperature at which a substance turns from a liquid to a gas
What does element, compound and mixture mean?
Element: a single type of atom
Compound: two or more elements chemically bonded together
Mixture: two or more elements or mixtures not chemically bonded together
