Elements Compounds and Mixtures Part-1

What is a substance?

  • Anything that cannot be broken into further particles by applying any physical processes is called a Substance.
  • Matter can be classified into two types of substances – Pure substances and Mixtures

What is a pure substance?

A substance that consists of only one type of particle is called a Pure SubstanceFor Example, Diamond, Salt, Sulfur, Tin. 

What is a mixture?

  • When we combine different substances into each other a mixture is formed. For Example, Lemonade is a mixture of three substances, Lemon Juice, Sugar and Water.
  • Which of these is a mixture or a pure substance?

Water, Copper, Chocolate cake, Hydrogen, Soil, Air

Mixture – Chocolate cake, Soil, Air

Pure substance – Water, Copper, Hydrogen

Classification of Matter

Physical Classification

Matter classified into

Solids , liquids , gases , plasma and Bose –Einstein condensate

Chemical Classification

Matter classifies into

Pure substances and mixtures

 

Types of Mixtures

There are two categories of mixtures: Homogeneous Mixtures and Heterogeneous Mixtures

 

 

 Differences between homogeneous and heterogeneous mixtures –

Homogenous Mixtures

Heterogeneous Mixtures

They have a uniform composition throughout 

They have a non-uniform composition

We cannot separate the components of the mixture through physical processes

We can separate the components through physical processes

Components cannot be seen through naked eyes

Components can easily be seen through naked eyes

The mixture is in single phase throughout

The substances can be of two different phases and we may see separate layers of the substances 

Example: A mixture of water and milk

Example: A mixture of oil in water 

 

What is a solution?

A solution is nothing but a uniform mixture of two or more substances. Homogenous Mixtures are solutions.

Solution constitutes of two types of substances, a solute and a solvent.

Solution = Solute + Solvent

What is concentration?

Concentration refers to the amount of a substance per defined space or can be defined as the ratio of solute in a solution to either solvent or total solution.

  • Percent by Mass = (Mass of solute / Mass of solution) X 100
  • Percent by Volume = (Volume of solute / Volume of solution) X 100

 

 

What is a suspension?

A suspension is formed when two or more substances are mix in a non-uniform manner. Heterogeneous mixtures are suspensions. The solute does not mix with the solvent and can be viewed through naked eyes.

 

 

Properties of Suspensions:

  • A suspension is a heterogeneous mixture.
  • We can see the particles of suspensions through naked eyes.
  • We can see the path of light through the particles of a suspension.
  • The particles of suspension tend to settle down when left undisturbed. Then, they can be separated using filtration.

 

What are colloids or colloidal solutions?

A colloidal solution or a colloid is a uniform solution of two or more substances. The particles are relatively very small that the solution appears as a homogeneous mixture but it is not.

Properties of colloids:

  • Colloids are heterogeneous in nature.
  • The particles of a colloid cannot be seen through naked eyes.
  • The particles scatter a beam of light passed through a colloid and produce Tyndall effect.
  • Colloids are stable in nature. The particles of colloids do not settle down if left uninterrupted.
  • We cannot separate the particles of a colloid through filtration. We use a method called Centrifugation to separate the particles of a colloid.