Mixtures and Separation of Mixtures

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

Topics in Chemistry

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 Mixtures and Separation of Mixtures Mixtures and Separation of Mixtures - part 2 Mixtures and Separation of Mixtures - part 3

Academic Questions in Chemistry

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

Which of the following is NOT a characteristic of chemical change?

  • A. A new thing is formed
  • B. It cannot be easily separated into it's constituents elements
  • C. A new chemical formula accompanies whatever is formed
  • D. The burning of candle is an example of a chemical change
  • E. Blood is an example of a chemical change
  • F. Iron rust is an example of a chemical change

Which of the following statement is FALSE concerning a physical change _____.

  • A. Substances formed in a physical change have a unique chemical formula and IUPAC name
  • B. It's a change that is easily reversible
  • C. It's a change that can be separated via an appropriate separation technique
  • D. No new substance is formed
  • E. A mixture of salt and water is a physical change
  • F. Physical change can result to a change in color and shapes of substances

The following substances will sublime EXCEPT _____.

  • A. Sodium Cryolite
  • B. Solid Carbon(IV)oxide
  • C. Arsenic
  • D. Sulphur
  • E. Iodine Crystals
  • F. Naphthalene

Which of the following is a state of matter?

  • A. Ions
  • B. Plasma
  • C. Compounds
  • D. Molecules
  • E. Atoms
  • F. None of the above

The ideal way of separating a mixture of blood is through _____.

  • A. Chromatography
  • B. Fractional Distillation
  • C. Centrifugation
  • D. Filtration
  • E. Separating Funnel
  • F. Fractional Crystallization

Which of the following separation technique is used to separate an insoluble solid that sediments in a liquid?

  • A. Crystallization
  • B. Fractional Crystallization
  • C. Sublimation
  • D. Separating Funnel
  • E. Fractional Distillation
  • F. Decantation

A _____ mixture is said to be uniform all through.

  • A. Homogenic
  • B. Heterogenic
  • C. Homogenous
  • D. Heterogenous
  • E. Concentrated
  • F. Diluted

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

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

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What are Mixtures?

Mixtures will always require a form 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 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 carry copper water bottles to school

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