States of Matter Flashcards
What is the arrangement and movement of particles in solids?
Tightly packed together in a regular arrangement and vibrate in fixed positions
What is the arrangement and movement of particles in liquids?
Close together but able to move past each other and vibrate and move around each other
What is the arrangement and movement of particles in gases?
Well separated with no regular arrangement and vibrate and move freely at high speeds
Compare the relative energies of particles in solids, liquids and gases
Particles in a solid have the least amount of energy and particles in a gas have the most energy
What does ‘interconversion of state’ mean?
When matter changes from one state to another die to changes in temperature or pressure
What are the forces between particles in solids, liquid and gases?
Solids - strong forces of attraction between particles which keeps them in their fixed positions, liquids - weaker attractive forces than in solids and gases - weakest intermolecular forces so particles are in random movement
How does a physical change differ from a chemical change?
A physical change involves changes in the forces between particles, the particles themselves remain the same and the chemical properties remain the same whereas a chemical change is different as it affects the chemical properties of the substance
Why are physical changes relatively easy to reverse?
there is no new product is formed during the changes of state
What happens when a solid is heated and melts into a liquid?
When heated the particles absorb thermal energy which is converted into KE, the particles in the solid vibrate more, this causes the solid to expand until the structure breaks and becomes a liquid
What happens when a liquid is heat and evaporated into a gas?
When heated, the particles in a liquid expand and some particles on the surface gain sufficient energy to overcome the intermolecular forces and evaporate, the boiling point all of the liquid particles gain enough energy to evaporate
What is a mixture?
Contains 2 or more elements or compounds that are not chemically combined together
What is a pure substance?
A single element or compound, not mixed with any other substance
How can you use melting point to distinguish between pure substance and mixtures?
Pure substance have a sharp exact melting point whereas mixtures melt over a range of temperatures since they consist of several elements/compounds
When is simple distillation used?
Used to separate a pure liquid from a mixture of liquid, only works when the liquid have different boiling points
How can ethanol be separated from water?
Distillation apparatus set up, mixture boiled, ethanol evaporates first and ethanol vapour cools in the condenser, condensing back to a liquid before being collected
When is fractional distillation used to separate mixtures?
Fractional distillation is used to separate all the elements/compounds in a mixture, these chemicals must have different boiling points to be separated
What is the difference between fractional and simple distillation?
Simple distillation is only able to separate the liquid with the lowest boiling point from the mixture whereas fractional distillation separates all the chemicals in a mixture, using their different boiling pointsn
How does fractional distillation work?
Oil is heated until it evaporates into the fractionating column and vapours rise up the fractionating column and condense at the different fraction, depending on the relative boiling point of each substance
What sort of mixture can filtration be used to separate?
Filtration is used to separate an insoluble substance from a solution
How can you separate an insoluble substance from a solution?
Place filter paper in a funnel, pour the solution containing an insoluble substance through the funnel into a conical flask and the insoluble substance will collect on the filter paper and the solution will collect in the conical flask
When is the process of crystallisation used to separate a mixture?
To separate a soluble solid from a solution if the solid decomposes when heated
How could you separate a soluble solid from a solution, if the solid decomposes when heated?
Crystallisation, pour the solution into an evaporating dish and heat gently, when the crystals start to form, remove the dish from the heat and leave to cool, once cold, filter the crystals out of the solution and leave them in a warm place to dry
What process can be used to identify substances in a mixture?
Chromatography
How does paper chromatography work to separate a mixture?
The mobile phase moves through the stationary phase so anything dissolved in the mobile phase will move with up the paper and compounds interact differently with each phase so will move different distances through the stationary phase meaning they will be separated
How can chromatography show the composition of a mixture?
Different coloured substances in the mixture will separate as they have different solubilities in the solvent and will travel at different rates
Why should pencil be used to draw the line along the bottom of the chromatography paper?
It won’t affect the experiment as it’s insoluble in the solvent
Why should the water in the beaker for paper chromatography be no deeper than 1cm deep?
If it’s deeper it will wash away the substance placed on the line on the chromatography paper
Why should you use a lid when carrying out paper paper chromatography?
To prevent the solvent evaporation
How many spots will a pure substance produce on a chromatogram? How would this be different for an impure substance?
Pure substance produce one spot and an impure substance contains more than one compound so will produce more spots
What is an Rf value?
The Rf value is the ratio between the distance travelled by the dissolved substances and the distance travelled by the solvent
How do you calculate Rf values?
Distance travelled by substance / distance travelled by solvent
When measuring measuring the distance moved by a substance in the chromatography paper, where should you measure between?
Measure from the pencil baseline to the middle of the spot of the substance
How can you use chromatography to see if a certain substance is present in a mixture?
Run a pure sample of this substance alongside the unknown mixture and if the Rf value of the pure substance matches the value of one of the spots from the mixture, it’s likely to be present
How could you separate salt from a mixture of salt and salt?
Salt is soluble in water, sand isn’t, add water to the mixture, filter the solution to remove the insoluble sand and then evaporate the water to collect the salt crystals
How can liquids be separated if they have different densities?
If liquids have different densities they will naturally separate unto two layers and to separate these layers, use a flask with a tap on the bottom and open the tap to collect the bottom liquid
What does potable mean?
Safe to drink
How can waste and groundwater be made potable?
Sedimentation: large insoluble particles sink to the bottom after the water is left still for a while, Filtration: removes small insoluble particles by passing the water through layers of sand and filters and Chlorination: kills bacteria and microorganisms which are too small to be removed by filtration
How can seawater be made potable?
Distilled, filter to remove insoluble particles, biol and Coll and condense the water vapour
What issues surrounded the process of making seawater potable?
Extremely expensive as it’s requires a lot of energy to boil large volumes of water, wastewater is toxic due to the high concentration of salt so must be disposed of carefully
What is deionised water?
Water that had had metallic ions removed
Why is deionised water used in experimental analysis?
Deionised water is used to prevent ions in the water interacting with the substances under analysis, if water wasn’t deionised, false positive results may be produced
