Topic 2 - States of Matter and Mixtures Flashcards
What are the states of matter
Solid, liquid, gas
The forces between particles in a solid are…. meaning the particles
Strong so the particles dont move from their positions.
The particles energy levels in a solid are
Low
Particles in a solid can
Vibrate if heated up which leads to the object expanding slightly.`
The forces between particles in a liquid are….. meaning
Medium, meaning the particles can move freely but stay near eachother. This means it doesnt keep a shape.
The particles energy levels in a liquid are
Medium: higher than solids but lower than gas
The particles in a liquid are always
Moving with random motion and they move faster when its hotter. It expands slightly when hot.
The forces between particles in a gas are….. meaning
There is no forces between the particles meaning thye move freely and travel in straight lines unless they collide.
Gases interact in container by
Bouncing around and filling the whole container at whatever pressure needed. They bounce of the walls and exert a pressure on the walls.
When gases get hotter they
Move faster. They either expand or increase in pressure
Solid to liquid is called….. and occurs because
Melting. Due to the particles gaining enough energy and vibrating enough to weaken the forces and break free.
Liquid to gas is called…. and occurs because
Evaporating. Due to more energy and vibrations, which allows the bond to be broken completely and the particles
to move freely.
Solid to gas is called…. and occurs because
Sublimation. When the particles in a solid gain so much more energy than they had, so they break there bonds instantly and move freely as a gas.
Gas to liquid is called… and occurs because
Condensation. Thye lose energy and stop vibrating as much, so that the intermolecular forces are reformed.
Liquid to solid is called…. and occurs because
Freezing. More energy is lost and vibrations reduce more. This means the intermolecular forces are strong enough to rearrange the particles into a lattice.
Difference between chemical and physical changes
Chemical changes happen during chemical reactions. It is when the bonds between atoms break and the atoms change places. The reactants are rearranged to form the products.
Chemical changes are much harder to reverse compared to physical changes.
How to predict a subtances physical state based on melting and boiling point.
Before melting point = Solid
Between melting and boiling point=Liquid
After boiling point=Gas
What does pure mean in chem
A substance completely made up of a single element or compound
A mixture is
A substance with more than 1 compound or seperate elements present
How to use melting and boiling points to determine purity
Pure substances have a sharp melting and boiling point whereas mixtures melt over a range of temperatures
What substances are simple distillation used for
Seperating a liquid from a solution eg. sea water to get pure water
Simple distillation steps
Have a distillation flask connected to a condenser to a beaker.
Put sample in distillation flask and heat up to the boiling point of the desired solution to seperate
It passes through the condenser and is collected at the beaker
Whats fractional distillation used for
a mixture of solutions eg crude oil
Fractional distillation steps
Put mixture in a flask and attach a fractionating column on top with the same set up as normal distillation with more collecting beakers.
Gradually heat the flask until a substance evaporates, then gradually increase for each subatnce
What is filtration used for
An insoluble solid mixed with a liquid
Filtration steps
Filter paper in a funnel voer a beaker. Run solution through funnel.
Crystalisation use
Seperating a soluble solid from a solution
Crystalisation steps
Put solution in an evaporating dish and heat gently until some water evaporates.
Leave to crystlaise at room temp, and the salt will separate from the solution.
What is chromotography used for
Seperating a mixture of soluble substances and identifying them
Two phases of chromotography
Mobile phase, stationary phase
Mobile phase is where
The molecules can move. This is always a liquid or gas
Stationary phase is wherw
The molecules cant move. This is a solid or thick liquid.
Paper chromotography steps
Stationary phase - Paper
Mobile phase - Solvent
Draw a pencil ine at the bottom of paper with a spot of the mixture on it.
Put solvwent in a beaker and dip paper int oit without it touching the line.
Put a watch glass on top of the beaker to prevent evaporation
Solvent will move up paper with some of the substances in the mixture, which will seperate and get in the stationary phase at different times.
Remove paper before the olvent reaches the top.
The amount of time the molecules spend in the two phases of chromotography depens on
Their solubility
Their attraction to the stationary phase.
Molecules with high solubility will therefore end up…. on the paper
Higher
What do you do if there are colourless chemicals on the chromatogram such as amino acidsq
Spray a locating agent
What is the R value for a spot on a chromatogram
The ratio of the distance travelled by the solute to the solvent
Rr =
Distance travelled by solute / Distance travelled by solvent
A certain substance in a chromotography mixture can be identified by
Doing the same with a pure sample and comparing the R values.
A pure substance when seperated in chromatography
Only gives one spot as all the molecules are the same solubility
Simple distillation and chromatography for ink(core practical) steps
Use distillation and measure the boiling point of the solvent to figure out what it could be.
Then paper chromotography could also be done using the ink as the mixture.
Thus allows you to find which different dyes the ink has, and the R values can be compared to oreferwence values to identify them
4 sources of water that can be purified for potable water
Surface water - lakes, rivers, resovoirs
Ground water - Aquifers, water underground
Waste water - Contaminated water by humans
Sea water - From oceans
Which is the purest water source
Ground water
Water treatment plans to purify include
Filtration - A wire mesh screens out large objects, then gravel and sand beds filter out other solids
Sedimentation - Iron sulfate or aluminium sulfate is added, so fine particles clump at the bottom
Chlorination - Chlorine gas is bubbled through to kill harmful bacteria and microbes
Sea water purifcation process
(Only in very dry countries)Distilled to get pure water. However it needs loads of energy so its very expensive.
What type of water should chemical analysts use
Pure water/ deoionised water
What is deionised water
Water that has had the ions in tap water removed(eg calcium, iron)
