Topic 2 - States of Matter and Mixtures Flashcards
What are the three states of matter?
Solid, liquid, gas
What do the properties of states of matter depended on?
The forces between particles
What force of attraction is there in the solid state of matter?
Strong, holding them in fixed positions in a regular lattice arrangement
What is the movement of particles like in a solid?
Particles don’t move from their position all solids keep a definitive shape and volume. They only vibrate in fixed positions.
What causes a solid to vibrate more?
Increase in temperature
How much energy do particles in a solid have?
Not much
What are forces of attraction like in liquid?
Some, they’re free to move past each one there but generally stick together
How does the shape and volume of a liquid change?
Liquids don’t keep the same shape, adapting to their container, but keep the same volume.
How much energy do liquids have
More than solids, but less than gases.
What causes increased speed of the particles in liquids?
Increasing the temperature
What are forces of attraction like in gases?
There’s little to none, they are free to move.
What is movement like in gases?
They travel in straight lines and only interact when they collide. They move constantly in random motion
How does the shape and volume of gases change?
They don’t keep a definitive shape and volume and will fill any container, exerting pressure on its walls
How much energy do gas particles have?
Lots, more than solid and liquid
What happens when temperature is increased to gases?
They will expand, or their pressure increases.
How does a solid melt?
-As particles are heated they gain more energy, which causes them to vibrate more and weaken the forces that hold them together making the solid expand
How does a liquid boil?
-When a liquid is heated it’s particles gain more energy which causes them to move faster and weaken bonds between them
How does a gas condense?
-As a gas cools, it’s particles no longer have enough energy to overcome the forces of attraction between them, leading to bonds forming
How does a liquid freeze?
-As a liquid cools, particles have less energy and so it’s particles move around less
How are chemical changes different to physical changes?
-Chemical changes are hard to reverse
What does it mean when a substance is pure?
If it is made up of one single element or compound
What are mixtures?
More than one compound present, or different elements not a part of the same compound
How can purity be tested for using melting points?
-Pure substances have specific melting and boiling points
What does simple distillation do?
Separate out a liquid from a solution
Step 1 of the pure water and sea water distillation
-Pour sample of seawater into distillation flask
What do you do after pouring a sample of sea water into a distillation flask (pure water and sea water distillation)?
- Connect the distillation flask to a condenser, and have the condenser over a beaker.
- Connect the bottom end of the condenser to a cold tap using rubber tubing.
- Run cold water through the condenser to keep it cool
What do you do after connecting everything and running cold water through the condenser in the pure water and sea water distillation?
- Gradually heat the distillation flask.
- The part of the solution that has the lowest boiling point will evaporate, in this case the water
What happens after the distillation flask has been heated in the pure water and sea water distillation?
The water vapour passes through the condenser where it cools and condenses and flows into the beaker where it can be collected
What happens after the water vapour passes through the condenser, where it cools and condenses in the pure water and sea water distillation?
Eventually, there will just be salt left in the distillation flask
What is the problem with simple distillation?
Things separated must have very different boiling points
What is fractional distillation used for?
To separate a mixture of liquids even if their boiling points are close together
Fractional distillation step 1
Put your mixture in your flask
What do you do after putting the mixture in the flask in fractional distillation?
- Attach a fractioning column with glass rods, with hottest part of the column being at the bottom, and the coolest at the top.
- Also attach a condenser and a thermometer at the top of the fractioning column.
What do you do after attaching everything in fractional distillation?
- Gradually heat the flask.
- The different liquids will all have different boiling points so they will evaporate at different temperatures.
What happens to liquids with lower boiling points in fractional distillation?
- The liquid with the lowest boiling point will evaporate first.
- When the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column.
What happens to liquids with higher boiling points in fractional distillation?
Liquids with higher boiling points may start evaporating, but the column is cooler towards the top so they will condense and go back down
What happens once the first liquid has been collected in fractional distillation?
When the first liquid has been collected, raise the temperature until the next one reaches the top
What is filtration used for?
To separate an insoluble solid from a liquid
What can filtration also be used?
-Purification of substances by removing solid impurities
How is filtration done?
- Put filter paper into a funnel and pour the mixture onto it.
- The liquid part will go through the paper, leaving behind a solid residue
What is crystallisation used for?
Separating a soluble solid from a solution
Step 1 of crystalliation
Pour the solution into an evaporating dish and gently heat the solution
What do you do after pouring the solution into an evaporating dish and heating it in crystallisation?
Once some of the water has evaporated, or crystals have started to form removing the evaporating dish from the heat
What should the salt start to do in crystallisation?
The salt should start to form crystals as it becomes insoluble in the cold, highly concentrated solution.
What do you do with the crystals in crystallisation?
Filter the crystals out of the solution, and leave them in a warm place to dry. You could also use a drying oven or a desiccator.
What are the two phases in chromatography?
Mobile phase and stationary phase
What is the mobile phase in chromatography?
Where the molecules can move. This is always a liquid or a gas
What is the stationary phase in chromatography?
Where the molecules can’t move - this can be a solid or a really thick liquid
What is the mobile phase in paper chromatography?
solvent
What is the stationary phase in paper chromatography?
paper
Why use a pencil to draw the line in chromatography?
- Draw a line in pencil at the bottom of the paper (not in pen because it’s soluble).
What do you do after drawing the pencil line?
- Put some solvent into the beaker
What do you do after putting solvent into the beaker?
Put a watch glass on top of the beaker to stop any water from evaporating
What do you do after putting a watch glass on top of the beaker?
- The solvent will move up the paper
What happens after the solvent moves up the paper?
The mixture will begin to separate out, forming spots at different points of the paper
What do you do after the mixture begins to separate?
Remove the paper from the solvent before it reaches the top. Mark where the solvent has reached
What should be done if a substance stays at the baseline?
Use a different solvent, as it is insoluble in that solvent
What should be done if some chemicals in the mixture are colourless?
Spray the chromatogram with a chemical called a locating agent
What is the piece of paper called at the end of chromatography?
Chromatogram
What is the equation for Rf value?
distance moved by substance/distance moved by solvent
What is Rf value controlled by?
-How soluble the molecule is in the solvent
Why does solubility increase Rf value?
Molecules with higher solubility in the solvent will spend more time in the mobile phase than the stationary phase, so will be carried further up the paper
What can chromatography be useful for?
-See is a certain substance is present is present in a mixture, by running a pure sample by a mixture and seeing if one of the spots have the same Rf value
What is ink?
A mixture of different dyes dissolved in a solvent.
What two separation methods can be used to analyse ink?
Simple distillation and chromatography
How can simple distillation and chromatography be used to analyse ink?
-Simple distillation can be used to find out what solvent the ink contains
What is potable water?
water that is safe to drink
What are the sources of water in the UK?
Surface water, ground water, waste water
What is surface water?
Water found on Earth’s surface in places like oceans, lakes, rivers, and reservoirs.
What is the disadvantage of surface water?
In much of England and Wales, surface water sources start to run dry during summer months
What is ground water?
From aquifers (rocks that trap water underground)
What is waste water?
Water that has been contaminated by a human process. Treating waste water is preferable to disposing of the water, which can be polluting.
Which sources of water generally need to be purified the most?
waste water and surface water
What is the process of purifying water?
1) Filtration- A wire mesh screens out large twigs etc and the gravel and sand beds filter out any other solid parts
What is an alternate method of obtaining potable water?
-In dry countries, sea water is distilled to produce drinking water
What water must be used in chemical analysis?
Deionised water
What is deionised water?
Water that has had metallic ions (such as copper or calcium ions) removed.
Why must deionised water be used in experiments?
They can interfere with experiments and give a false result
