Topic 2 - States Of Matter And Mixtures Flashcards
What are the three states of matter ?
Solid
Liquid
Gas
What are the forces of attraction like between particles in a solid?
Do the particles move in a solid?
How much energy have they got?
- strong forces of attraction which hold them together in fixed positions in a regular lattice structure.
-the particles don’t move in a solid , they vibrate on the spot.
- they don’t have much energy
What are the forces of attraction between particles like in a liquid?
How do the particles move in a liquid?
-There are some forces of attraction in a liquid.
-the particles constantly move with random motion.
Particles have more energy than a solid but less than a gas.
What are the forces of attraction between particles like in a gas?
How do particles in a gas move?
- there are next to no forces of attraction between particles in a gas.
What happens when a solid is heated?
-The particles gain energy and begin vibrating more.
-weakens the forces thay hold a solid together
-at a certain temp it will reach its melting point where the particles will have enough energy to break free from the positions and melt
Why are chemical changes harder to reverse than physical changes?
Because the atoms are rearanges
What is a pure substance?
A pure substance is made up of only one element or compound
How to test is a substance is pure?
By using melting points.
If it is pure it should have a sharp melting point unlike a mixture that may melt over a range of temperatures.
What does simple distillation do?
Simple distillation separates a liquid out of a solution.
How to carry out simple distillation core practical.
1)pour your sample into the distillation flask.
2)connect the bottom end of the condenser to a cold tap using rubber tubing. Run cold water through the condenser to keep it cool.
3)heat the distillation flask. The part of the solution with the lowest melting point will evaporate first.
4)the water vapour passes through the condenser where it cools and condenses back into liquid, flowing into the beaker where it’s then collected.
5)eventually you’ll end up with salt in the flask
What’s the problem with distillation?
It can only be used to separate mixtures that have very different boiling points between the compounds or elements
Why would we need to use fractional distillation?
How to carry out fractional distillation.
- if the mixtures of liquids have similar boiling points.
1)put your mixture in a flask.
2) attatxh a fractionating column and a condenser above the flask
3) gradually heat the flask, the different liquids will have different boiling points so will evaporate at different times
4)the liquid with the lowest boiling point will evaporate first.
5) liquids with higher boiling points might also start to evaporate but the column is cooler towards the top so they will imidiatelt condense and roll back down into the flask.
What is filtration used to separate?
Filtration separates an insoluble solid from a liquid.
What is filtration used to separate?
Filtration separates an insoluble solid from a liquid.
How does filtration work?
You put filter paper into a funnel and pour your mixture through it. The liquid should pass through and the solid residue should remain in the filter papers.
How does filtration work?
You put filter paper into a funnel and pour your mixture through it. The liquid should pass through and the solid residue should remain in the filter papers.
What’s crystallisation used for?
To separate a soluble solid from a solution.
How does crystallisation work?
1) pour the solution into an evaporating dish and gently heat it. Some of the water will evaporate and the solution will become more concentrated.
2)once you see crystals start to form, remove the dish from the heat and leave the solution to cool.
3)the salt should start to form crystals as it starts to become insoluble in the cold , highly concentrated solution.
4)filter the crystals out the solution and leave them in a warm place to ddy
What are the 2 phases in chromatography and what do they mean?
A mobile phase- where molecules can move. Always a liquid or a gas
A stationary phase- where molecules can’t move. Always a solid or a thick liquid.
What is the stationary phase in paper chromatography ?
Piece of paper.
What is tbe mobile phase in chromatography?
The solvent
How to carry out chromatography practical?
1)draw a baseline at the bottom of the paper.use pencil. Put a spot of the mixture on the baseline.
2) but some solvent in the beaker. Dip the bottom of the paper in it but not the spot.
3)the solvent will start moving up the paper, when the chemicals in the mixture dissolve in the solvent they will move up the paper too.
4)you will see the differnt chemicals in the mixture separate out.
5)mark the distance the solvent has moved in pencil ( solvent front)
How to calculate the Rf value?
Rf value = distance traveled by substance / distance traveled by solvent.
What does the Rf value depend on?
-How soluble the molecules are in the solvent.
-how attracted they are to the stationary phase.
