Separate three Components from Iron, Sand and Common Salt Mixture

Our Objective:

You are given a combination of iron, sand, and table salt. The three parts of this combination should be separated.


The Theory:

Mixtures are created when two or more elements or compounds combine without a chemical reaction. The components may not have to mix in a particular ratio to make a combination. These are categorised into two that is Homogeneous and heterogeneous mixtures.

Homogeneous mixtures are mixtures in which the mixed components are uniformly distributed throughout the mixture.

Heterogeneous mixtures are types of mixture in which all the components are thoroughly mixed, and all the particles can be seen under a microscope. We can quickly identify the features, and naked eyes can see more than one phase.

Generally, materials are separated according to differences in their physical properties. During the separation process, it is essential not to chemically change any of the parts of the mixture if possible. This avoids costly chemical processes and loss of material. It is best to try to separate one component at a time, which means that this experiment can be expected to have at least three stages corresponding to the removal of each part from the mixture.

The three components that make up the combination in this experiment are solids with distinctly different physical characteristics, which facilitates separation.

Separation technique theory

If you're trying to decide how to separate two or more materials, you should start by comparing their physical properties. Since none of the three is liquids in this scenario, state distinctions are irrelevant. Because iron is magnetic, but the other two are not, a magnet might be used to draw the iron filings from the combination while leaving the salt and sand in their place. Sand is not water soluble, but salt is. This implies that the two can be combined and swirled in the water. Sand will not dissolve, but the salt will. The three items have been divided based on these distinctions.

Material State Magnetic (Yes/no) Water soluble (Yes/No)
Iron Fillings Solid Yes No
Sand Solid No No
Salt Solid No Yes


Different methods for separating the mixtures


1. Threshing

The process of separating grains from sun-dried stalks is called threshing. In this process, the stalks are beaten against any hard surface such as a large rock or a stone slab etc., to free the grains. Threshing can also be done with the help of a mechanical device called a thresher.

2. Winnowing

After harvesting the wheat from the field, a farmer threshes it to loosen the chaff from the grain inside. The chaff is lighter, and the grain is heavier. Therefore, on a windy day, the farmer allows the mixture of chaff and grain to fall from a height. The chaff, being lighter, blows with the wind to a distance while the heavier grain falls. The farmer gets two separate heaps of chaff and grain. This process of separating the wheat grain from the chaff is called winnowing.

3. Sieving

This method is used to separate small pebbles mixed with seeds in a large quantity. In this process, a sieve is used for sieving grains. A sieve has small holes which allow pebbles to pass through it. The grains are retained in the sieve and are thus separated. They depend upon the size of particles to be separated.

4. Magnetic Separation

Using a magnet, iron filings can be separated from a mixture of iron and sand. This process is known as magnetic separation.


Separation of Insoluble Solids from liquids


5. Sedimentation

This process is based on the densities of different components of a mixture. The process of setting down heavy insoluble particles in a mixture of water and insoluble substances is called sedimentation.

6. Decantation

Decantation is pouring out a clear liquid from a vessel (after sedimentation) without disturbing the sediments (heavy insoluble settled particles).The above method has two disadvantages.

(a) It cannot be used for the miscible liquids that dissolve in one another. For example, petrol mixed in kerosene oil or salt or sugar solution in water.

(b) During the decantation process, a small quantity remains unseparated; thus, it gets wasted.

7. Filtration

Filtration is separating suspended solid matter from a liquid by causing the latter to pass through the pores of some substance, called a filter. The fluid which has passed through the filter is called the filtrate. The filter may be paper, cloth, cotton wool, asbestos, slag or glass wool, unglazed earthenware, sand, or other porous material.

8. Condensation

Condensation is the change of water vapour into liquid water.

9. Distillation

Distillation is the process of separating the component of substances from a liquid mixture by selecting evaporation and condensation.


The Universal Solvent “Water”

Water is an excellent solvent since it can dissolve a variety of things. Water is called the "universal solvent" since it can dissolve more compounds than any other liquid.  

  • Miscible liquids are substances that mix seamlessly with water in all ratios. Alcohol, for example, may combine with water.
  • Immiscible liquids are substances that do not combine and create a distinct layer. For example, oils and water did not mix well.

The carbonated drinks like Coco-Cola are a mixture or not?

Coca-Cola is a homogenous combination even when sugar and water are combined in the solution equally. You can also see the essential components in a homogenous mix, such as Coca-Cola; however, in a heterogeneous mixture, such as a salad, you cannot.


Learning Outcomes:

  1. Students will learn about the basic separation techniques from the experiment.  
  2. They will get familiarised with the term mixtures and types of mixtures.