Separation of mixtures Flashcards
What is an element?
An element is a substance that contains just one type of atom
What is a mixture?
A mixture is made up of two or more different substances that aren’t chemically joined together
What is a compound?
A compound is made up of two or more types of atoms that are chemically joined together
Write down two types of particles
Atoms and molecules
Write an example of an element, a mixture and a compound
Element: Hydrogen
Mixture: Air
Compound: Water
Can mixtures be separated and why
Mixtures can be easily separated as they are not chemically joined together
What are 4 different methods of separation
Filtration, Evaporation, Simple distillation and chromatography
Where can we use filtration
We can use filtration to separate an insoluble solid from a liquid
What is an insoluble substance
An insoluble substance is one that does not dissolve in water
What is a real-life example of where we can use filtration
We can use filtration to separate sand from water
Write down the process of filtration
Firstly, pour the mixture into a filter funnel aligned with some filter paper. The insoluble solid will stay on the filter paper and will be collected as the residue, while the water will pass through and will be collected as the filtrate in the beaker. This is because liquid particles are small and can pass through the filter paper, while the solid particles are bigger and they therefore can’t. Then, the sand is washed and is dried in an oven
What is the residue
The residue is the solid left on the filter paper
What is the filtrate
The filtrate is the liquid that comes through the filter paper and is collected in the beaker
Write one real life use of filtration
Filtration is used in the making of drinking water. Solid impurities are firstly removed using filtration. Then, the water is treated with chlorine to kill microorganisms
Where can we use evaporation
Evaporation is good for separating a soluble solid from a liquid
Write one example of evaporation
One example of evaporation is separating salt from water
Write down the process of evaporation
Pour the solution into an evaporating basin. Heat the evaporating basin until all the water is evaporated, leaving the salt in the basin. This happens because water has a lower boiling point than the salt, so it evaporates first
What is indirect heating
Indirect heating is another form of evaporation. A beaker full of water is placed under the evaporating basin. The beaker is heated, which turns water into steam. As the steam rises, it heats the evaporating basin, causing the liquid to evaporate
What are the pros and cons of indirect heating
Pros: It is more accurate, as spitting is prevented
Cons: It is more time consuming
What is distillation used for
Distillation is used to separate a liquid from a soluble solid or to separate one liquid from another.
Write down the process of distillation
The mixture is first placed inside a distillation flask and is heated together with anti-bumping granules to prevent violent boiling. The substance with the lowest boiling point turns into vapour and enters the condenser. In the cold condenser, the vapour is cooled down and is condensed back into a liquid. The pure liquid is then collected as the distillate.
What are anti-bumping granules
Anti-bumping granules are small pieces of broken porcelain that prevent violent boiling and help the liquid boil smoothly
What are miscible liquids?
Miscible liquids are liquids that mix together
Example: Ethanol and Water
What do two liquids have to be in order to be separated
They need to be miscible and to have a difference in boiling temperature of over 30 degrees
Write down 6 precautions to achieve the separation with distillation
1: Type of heating: If the liquids are flammable, you should use a water bath or an electric heater to heat the liquids rather than a naked flame
2: Thermometer: The thermometer should be placed at the entrance of the condenser, so that the exact boiling point is recorded
3: Anti-bumping granules: Place pieces of broken porcelain in the mixture to allow it to boil smoothly
4: Connections to the condenser: Water should be coming in at the bottom and going out at the top. This prevents air from being trapped inside the condenser, something that could cause it to crack
5: Collection vessel: The collection vessel should have a small opening to reduce evaporation
6: The apparatus should be open to prevent pressure building up when the apparatus is heated
Why is water leaving the condenser hotter than the water entering
Water leaving is hotter because the heated vapour particles that enter the condenser move towards the water since it is colder
What is chromatography
Chromatography is a technique used to separate dissolved substances that have different colors
What can we identify with chromatography
Chromatography helps identify whether a substance is pure and identify what an unknown sample is
Write down the process of chromatography
Place a spot of the mixture on a pencil line at the bottom of the chromatography paper. Put the chromatography paper into a container containing a suitable solvent. The solvent is absorbed and it rises up, causing the different components of the mixture to begin to separate. The different solutes have traveled different distances according to their solubility
Why do we draw a line with a pencil on the chromatography paper
We draw the line with a pencil as it is insoluble and it won’t get mixed up when placed in the water
