Mixtures and Separation of Mixtures

Alfred Ajibola - Wed, 26th June, 2019 @ 06:16: AM

Topics in Chemistry

Salts and Types of Salt in Chemistry Mixtures and Separation of Mixtures Separation of Mixtures part 2 Separation of Mixtures part 3 Physical Change, Chemical Change, Element, Compound and Mixture Electrolysis, Electrolyte, Electrode, Anode and Cathode Grahams law of diffusion Physical Properties of Metals Daltons Atomic Theory and its Modifications Periodic table and Classification of Elements

Academic Questions in Chemistry

Please check out our Test Your Knowledge page to see all Questions and Answers

The reaction involving an acid and a base is termed _____.

  • A. Hydrolysis
  • B. Neutralization
  • C. Combustion
  • D. Displacement
  • E. Decomposition
  • F. Sublimation

Which of the following is NOT a type of salt?

  • A. Acid salt
  • B. Basic salt
  • C. Double salt
  • D. Tripple salt
  • E. Complex salt
  • F. Normal Salt

The only metal that exist as liquid at room temperature is _____.

  1. Nickel
  2. Duralumin
  3. Mercury
  4. Lead
  5. Titanium
  6. Cesium

What are Mixtures:

Mixtures will always require a form separation. The reason is because a mixture must contain more than one substance. Take for instance, water (H2O) is a pure substance; but when we add common salt (NaCl) to it, the water no longer becomes pure (since it has been mixed with another substance). Together, the water and salt are considered to be mixtures and thus may be separated in order to regain its constituents, that is, the salt and water respectively.

A mixture always contain two or more substances in any proportion

Based on the uniformity of the mixture, we could classify a mixture as either homogenous or heterogeneous.

The composition of substances in a homogenous mixture is uniform all through. For instance, the mixture of salt and water will be homogenous.

The liquid that dissolves the solid is known as the solvent. (Water in the above instance).

The solid that is dissolved by the solvent is known as the solute. (Salt in the above instance).

A mixture is said to be heterogeneous if different sections of the mixture have varying composition.

An example of a heterogeneous mixture is sand and water.


Separation of Mixtures:

In chemistry, students are expected to work with substances like salts, acid and bases. Recall that substances may be classified in two ways. These are:

  1. Physical substances: They are classified into solid, liquid and gases. You may read on solid, liquid and gases here.
  3. Chemical substances: They are classified into elements, compounds and mixtures. Please read on element, compound and mixtures here.

It is important to note that the technique for separating one mixture will vary with another. This is due to the different nature of components present in the mixture, together with their physical properties like boiling point, melting point and solubility among others. Please read on the physical properties of metals here.


Below are types of separation techniques (for separating mixtures) :

(1) Filtration

Filtration is used as a method to separate an insoluble solid from a liquid. For instance:

  • Sand and water
  • Lead tetraoxosulphate(XI) (PbSO4) and water (H2O)
  • A solution of Calcium trioxocarbonate(IV) (CaCO3) and Sodium Chloride (NaCl)
  • Pebbles and water

The material utilized in carrying out the process of filtration could be a filter paper, sieve with microscopic pores or even a cotton material. The liquid that is collected into the filtration flask is known as the filtrate while the solid that remains on the filter paper is called the residue.

Note: Filtration is a commonly used process in the purification of a town’s water supply. In this case, filter beds are used.


(2) Decantation

Decantation is a process used for the separation of an insoluble solid from a liquid; and the insoluble solid must settle at the bottom of the container, leaving a clear liquid above.

Sedimentation is a term used when an insoluble solid settle at the bottom of a container

During the process of decantation, we need to carefully pour off the top/upper clear liquid leaving behind the insoluble solid in the container. Although decantation may be quite similar to filtration with regards to what is separated, the fact remains that decantation is less effective since it cannot ensure complete separation of the insoluble solid from the liquid.


(3) Separating funnel

A separating funnel is used to separate two immiscible liquid, for instance, water and oil, Kerosene and water, etc. The two immiscible liquids that are to be separated will usually have different densities or weights; and as a result, one will rise above the other. With regards to water and oil, water has a higher density of 1.003g/m3 and will remain at the bottom (sinks) as the oil floats above it (since it has a lesser density of 0.811g/m3).

Immiscible or Non Miscible liquids are liquids that do not dissolve in each other

Image Credit: Quora

When the mixture of the two immiscible liquid are put in the separating funnel, the tap/stopcock is opened and the liquid with the higher density is first collected (water in our case) followed by that with the lesser density (oil).

Note: A separating funnel is also called a separatory funnel.


(4) Evaporation

Evaporation is used to separate the components of a soluble solid in a liquid and the solid must not be decomposed on heating. The mixture of sodium chloride in water can be separated through evaporation.

The basic apparatus required to carry out evaporation are

  • Bunsen burner
  • Tripod stand
  • Evaporating dish

After evaporation, the liquid will be lost to the atmosphere while the solid (salt in our instance) remains in the evaporating dish.

The solid that remains in the evaporating dish is known as residue


Please read part 2 here

Please read part 3 here


Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

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Amazing facts in Chemistry

The only letters that failed to appear on the periodic table are letters:

J     &     Q

Gold and copper are the only two non-silvery colored metals. Please read some interesting facts about gold here