Mixtures and Separation of Mixtures

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

Topics in Chemistry

Le Chatelier's Principle: Changes in Concentration and Pressure explained in Dynamic Equilibrium Chemical Equilibrium: Dynamic Equilibrium in Chemistry Static and Dynamic Equilibrium explained with their Differences Chemistry Scheme of Work, SS1, First Term Chemistry Scheme of Work, SS1, Second Term Chemistry Scheme of Work, SS1, Third Term Compounds in Chemistry: Characteristics of Compounds Types of Mixture: Homogenous and Heterogeneous Mixtures Mixtures: Characteristics of Mixtures Physical Properties of Matter explained with Examples Chemical Properties of Matter explained with Examples Differences between Physical and Chemical Change Ionic Theory and Electrolysis Physical and Chemical Properties of Acids States of Matter: Characteristics of Solids Liquid State of Matter: Characteristics of Liquids Gaseous State of Matter: Characteristics of Gases Molar Mass, Worked Examples and Differences with Molecular Mass Elements: Characteristics of Elements Salts and Types of Salt in Chemistry

Academic Questions in Chemistry

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

Which of the following statement is false concerning hydrocarbons?

  • A. Hydrocarbons can be aromatic

  • B. Hydrocarbons are made up of carbon and hydrogen only

  • C. Alkynes are aliphatic hydrocarbons

  • D. Alkenes have a carbon-carbon double bond in their structure

  • E. Benzene ring has a carbon-carbon triple bond in its structure

  • F. Hydrocarbons are the main constituents of petroleum and natural gas

The ability of carbon to form long chain of itself is called _____.

  • A. Carbon chain reaction

  • B. Catenation

  • C. Carbontion

  • D. Carbontion

  • E. Organic chemistry

  • F. Carbon moleculation

Calculate the relative molecular mass of methane. (Carbon = 12.001, H = 1.00794).

  • A. 13.00894 amu

  • B. 11.00206 amu

  • C. 12.00794 amu

  • D. 14.001 amu

  • E. 15.001 amu

  • F. 16.033 amu

Which of he following is not a fact concerning gold?

  • A. 24 karat gold is the purest gold element

  • B. It is the 50th rarest metal amongst all elements found beneath the earth crust

  • C. It is the most malleable and ductile pure metal ever known

  • D. It is the only metal with a golden color

  • E. Gold is non toxic and can be eaten with food

  • F. It's present inside the earth crust in all seven continents

Which of the following is not an example of a chemical change?

  • A. The burning of wood
  • B. The melting of candle wax
  • C. The decomposition of food
  • D. The rotting of leaves
  • E. The lightening of a match stick
  • F. None of the above

Which of the following is not a fraction of crude oil?

  • A. Gasoline
  • B. Naphtha
  • C. Benzene
  • D. Wax
  • E. Paraffin
  • F. Lubrication Oil

The Separating Funnel is a technique used in the separation of mixtures. Another name for Separating Funnel is the _____ Funnel.

  • A. Partition
  • B. Separatory
  • C. Division
  • D. Liquid
  • E. Half
  • F. Dividing

2NH4+(aq) + Ag+(aq) -> 2H4AgN

The equation above represents _____ acid.

  • A. Svante Arrhenius'

  • B. Brønsted–Lowry's

  • C. Gilbert Lewis'

  • D. Avogadro's

  • E. Sir Isaac Newton's

  • F. Albert Einstein's



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What are Mixtures?

Mixtures will always require a form of separation. The reason is because a mixture must contain more than one substance.

Please read more on Mixtures and their Characteristics here.

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 will always contain two or more substances in any proportion.

Please read more on Elements and their Characteristics here.

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).


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 solids, liquids and gases.
    Please read on Solids, Liquids and Gases with their Characteristics here.
  2. Chemical Substances: They are classified into elements, compounds and mixtures.

Note: It is important to state 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.


Separation Techniques

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, a mixture of:

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

Below is an image showing the Filtration process:

Filtration - Len Academy

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.

You can read on Compounds in Chemistry and their Characteristics here.


(2) Sedimentation and Decantation

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

An instance where decantation can be used is in the separation of water and sand. Sand is insoluble in water and will sediment at the bottom, leaving a clear liquid above.

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

The clear liquid above the sediment is referred to as the supernatant.

Sedimentation and Decantation - Len Academy

During the process of decantation, we need to carefully pour off or decant the top/upper clear liquid (supernatant) leaving behind the insoluble solid (sediment) in the container.

Note: 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.

Note: 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.

Please read more on Density and Specific Gravity here.

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.

Below is an image of a Separating Funnel:

Separating Funnel - Len Academy

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 lower density (oil).

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.

A mixture of sodium chloride in water can be separated through evaporation.

Evaporation Separating Technique - Len Academy

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.

Please read on Layers and Composition of the Atmosphere here.

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

Please read on the Separation of Mixtures - Part 2 here

Please read on the Separation of Mixtures - Part 3 here

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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

Copper is the only metal that is naturally antibacterial. This is why you would see some children utilize 'copper' water bottles in schools

Water actually freezes faster when it’s warm than when it’s cold

Most element in their pure state exists physically in different forms. For instance, pure carbon can exist as both diamond and graphite. This phenomenon is called allotropy.

Please read on modification of Dalton's atomic theory here.

If you pour a handful of salt into a full glass of water, the water level will go down rather than overflowing the glass.

Similarly, if you mix half liter of water and half litre of alcohol, the total volume of the liquid will be les than one litre


A major challenge encountered when calculating molecular mass is that it becomes difficult or impossible to calculate especially when the relative molecular mass of large molecules, polymers and macromolecules are involved.

Examples of large molecules (with indefinite molecular masses) include carbohydrates, cellulose and complex sugars.

The large molecules (above) have no specific chemical formula throughout their volume.

Please read more on Carbohydrates and Sugars here

Understand that Relative Molecular Mass prove to be useful only when we calculate substances with small and definite molecular sizes. This was proven through the Modifications of Dalton's Atomic Theory.

Please read on Dalton's Atomic Theory and its Modifications here.

Calculate the Relative Molecular Mass of Methane (CH4). (Carbon=12.001 and H=1.00794)

  • Molecular Mass = Atomic mass of carbon + Atomic mass of Hydrogen
  • Methane is composed of one atom of Carbon and 4 atoms of Hydrogen.
  • 12.001 + (1.00794 x 4)

Molecular Mass of Methane = 16.033 amu

Please read more on molecular mass here

Calculate the Relative Molecular Mass of Water (H2O). (Oxygen=15.9994 and Hydrogen=1.00794)

  • Molecular Mass = Atomic mass of Hydrogen + Atomic mass of Oxygen
  • Water contains 2 atoms of Hydrogen and 1 atom of oxygen.
  • (1.00794 x 2) + 15.9994

Molecular Mass of Water = 18.015 Da

Please read on Emperical Formula and its Calculations here

Gold ; Len Academy

Below are some facts about gold

  • It is the only metal that has a gold (golden) color.

  • Gold is present inside the earth crust in all the seven continents.

  • Pure gold is soft and very stretchable (It can even be stretched into threads).

  • The Latin name of Gold is aurum which means 'shining dawn'. For this reason, its chemical symbol is 'Au'.

  • Gold is a very good conductor of electricity. This is why it’s sometimes used in making USB and audio cables.

  • Gold is non toxic and can be eaten with food. It is sometimes added to desserts in some expensive restaurants.

  • The term Gold originated from an ancient English word 'geolu' which means yellow.

  • 24karat gold is the purest gold element.

Please read more interesting facts about gold here

An acid is a substance that produces Hydrogen ions (H+) when dissolved in water (or when in the form of an aqueous solution).

Svante Arrhenius definition of Acid


An acid is a substance that donates a proton in a chemical reaction.

Brønsted Thomas Martin Lowry definition of Acid


An acid is a substance that accept an electron pair in a chemical reaction.

Gilbert Newton Lewis definition of Acid


Finally, Acids can also be also defined as substances that gives out hydronium ion (H3O+) when dissolved in water.


In summary, all acids will always contain the positive H+ (cation) and an anionic group in their formula. For instance, the acid HCl (Hydrogen Chloride) contains H+ as cation and Cl- as its anion.

Please read the explanations of the above definitions of acid here