Prior learning: To fully understand this material you will need to have learnt about the different states of matter and the changes of state, solubility and solutions.
The appropriate method to use for separating the components in a mixture depends on the physical states of the things that are being separated. To summarise:
| Technique | What it does: |
| Filtration | Separates an insoluble solid from a liquid or solution |
| Crystallisation | Separates a solute (solid that has been dissolved) from a solution |
| Simple distillation | Separates a liquid (the solvent) from the solution it is part of |
| Fractional distillation | Separates the liquids in a mixture of liquids, based on their boiling points |
| Paper chromatography | Separates dissolved dyes/pigments based on their different solubilities |
We also need to understand a little about how each of these techniques works:
Filtration
The insoluble solid particles can’t pass through the tiny gaps in the filter paper, but the liquid particles can. As a result the solid (called the residue) remains in the filter paper, separated from the remaining liquid or solution which has passed through the filter paper. This liquid is termed the filtrate.
Crystallisation
- The solution is heated until enough of the solvent (water) has evaporated to make the solution saturated.
- We can tell when the solution is saturated by dipping a glass rod into the solution to remove a drop and seeing if the drop goes cloudy and crystals start to form as it cools.
- Once the solution is saturated, the Bunsen is turned off and the solution is allowed to cool – solubility decreases with temperature, and the solute that can’t remain dissolved forms crystals.
- The crystals are removed from the remaining solution by filtering.
- The crystals are dried (in a warm oven, or just left to dry).
Watch what happens once a saturated solution is allowed to cool.
Simple Distillation
The solution is heated in the flask. The solvent boils, becoming a vapour, which travels to the condenser. Here it is cooled and condenses, collecting as a pure liquid called the distillate. What remains in the flask is the same mixture, but containing less solvent – a more concentrated solution.
Fractional distillation
This technique works in a very similar way to simple distillation, but the idea of the fractionating column is to get a temperature gradient, cooler at the top and hotter at the bottom. This allows careful control of the temperature at which the distillate is being collected, allowing different liquids in a mixture to be separated, each turning into a vapour and being cooled and condensed in the condenser at their own individual boiling points.
Paper Chromatography
Mixtures of substances dissolved in a solvent, such as the dyes in ink or the food colourings used in sweets and other food products, can be separated to reveal which different dyes or additives have been used in the mixture.
The process for doing this is paper chromatography. It separates the components in the mixture based on differences in their solubility: the more soluble each component, the further it travels towards the top of the paper in the chromatography experiment. Insoluble components won’t move at all, remaining on the baseline (shown above as the pencil line with A, B and C marked along it). The ink labelled B can be seen to be made from a blue, a pink and a dark purple pigment. The blue is the most soluble, and the purple least soluble.
FAQs
Filtration or Sedimentation
The most common method of separating a liquid from an insoluble solid is the filtration. Take, for example, the mixture of sand and water. Filtration is used here to remove solid particles from the liquid. Various filtering agents are normally used like filtering paper or other materials.
What are the 10 methods of separating mixtures? ›
Methods for how to separate mixtures include chromatography, distillation, evaporation, crystallization, filtration, dissolving, magnetism, and manual separation.
Which separation technique is the best? ›
Though chromatography is a simple technique in principle, it remains the most important method for the separation of mixtures into its components.
Which separation technique is fastest? ›
Separation of Mixtures by Distillation
Distillation is a fast way to separate mixtures of two or more pure liquids. Distillation is a purification method that involves vaporizing the constituents of a liquid mixture, then condensing and isolating them.
Why is separation so hard? ›
Going through a breakup is experiencing real loss, and the bigger the love, the connection and the intimacy, the bigger the pain and suffering. This loss can take over your thoughts and emotions and you will most certainly experience grief. You lost a loved one and now there is a void in your life.
Where do I start with separation? ›
When Love Has Gone: Five Steps Towards Separation
- Step 1: Decide Who Will Leave. You need to decide who will leave the joint home and where your children or pets will live. ...
- Step 2: Gather Documents. ...
- Step 3: Make A List. ...
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Summary
- Mixtures can be separated using a variety of techniques.
- Chromatography involves solvent separation on a solid medium.
- Distillation takes advantage of differences in boiling points.
- Evaporation removes a liquid from a solution to leave a solid material.
- Filtration separates solids of different sizes.
Sand and water/ Cereal and milk/ Sugar and salt/ Salt and water/ Water and ethanol/ Water and pepper/ Cement/ Blood, all of these are examples of mixtures that can be separated by physical methods.
Which method gives better separation? ›
Distillation is an effective method to separate mixtures comprised of two or more pure liquids. Distillation is a purification process where the components of a liquid mixture are vaporized and then condensed and isolated.
How do you separate mixtures Year 5? ›
Sieving allows smaller solids to pass through while removing larger solids from the mixture. For mixtures of small solids and liquids, filtration can be used. Filtration removes the solids from the liquid, allowing the liquid to pass through. To separate dissolved solutes from solutions, evaporation can be used.
Chromatography is the most useful and the latest technique of separation and purification of organic compounds.
Which type of mixture is most easily separated? ›
Explanation: The kind of a mixture that can be easily separated into its components by simple techniques such as filtering or decanting is a heterogeneous mixture. Heterogeneous mixtures are composed of large parts that are visibly different from each other.
Which type of substance is easiest to separate? ›
It is easiest when components are in different phases, e.g., solid and gas, liquid and solid, or two immiscible liquids, like oil and water.
How to remove solute from solution? ›
Thus for separating solute from the solution we can use the evaporation process. By using the evaporation method, the solvent can be evaporated, that is it will change its form from liquid to gaseous on heating, and thus we will be left out with the solute.
What is the most common separation process? ›
Distillation. Distillation and its companion processes, azeotropic and extractive distillation, are by far the most widely used separation processes for mixtures that can be vaporized. Distillation is a process for isolating components from a mixture based on differences in boiling points.
How do you make separation easy? ›
5 Tips For A Healthy Separation
- Be Courteous To Your Partner. Just because you're separating doesn't automatically mean you have to stop being courteous to your partner. ...
- Carry On As You Have Been (At Least For A While) ...
- Always Consider Amicable Divorce Options. ...
- Take Advantage Of The Support That's Out There.
