Is Matter Around Us Pure

Substances made up of two or more type of pure matters and can be separated by simple physical methods, are called MIXTURE. For Example: Air, salt solution in water, sugar solution in water, milk, etc.

Air is the mixture of many gases, and thus called mixture.

Sugar solution in water, salt solution in water, cold drink, medicines, etc. are some other Examples of mixture.

Most of the Matters exist around us are not in pure form rather they exist in the form of Mixture.

Types of Mixture:

On the composition of substances which form a mixture, Mixture can be divided into two types ? Homogeneous Mixture and Heterogeneous Mixture.

Homogeneous Mixture

Mixtures which have uniform composition throughout are called Homogeneous Mixture. For examp: Salt solution in water, sugar solution in water,

Homogeneous Mixtures are known as Solution also. In other words all the solutions are homogeneous mixture.

Heterogeneous Mixture

Mixtures which do not have uniform composition throughout or have un-uniform composition are called Heterogeneous Mixture. For Example: Mixture of sand and water, mixture of sodium chloride and iron fillings, etc.

Mixtures can be divided into following three types on the basis of composition and size of their particles. These are

(1) Solutions

(2) Suspensions

(3) Colloidal solutions

Solutions

A homogeneous mixture of two or more substances is called solution. For Example: Lemonade, soda water, solution of water and sugar, etc.

Homogeneity in a solution is at the particle level. Such as a salt or sugar solution in water tastes same throughout.

Solutions may be solid, liquid or gas. Alloys are Example of solid solution and air is an Example of gaseous solution.

Composition of a Solution

A solution is made of solvent and solute as its component.

Solvent

The component of the solution that dissolves the other component in it is called solvent.

The component of a solution present in larger amount is called the solvent.

Solute

The component of the solution that is dissolved in the solvent is called the solute.

The component of a solution present in smaller amount is generally called solute.

Example: In a salt solution in water. Water is solvent as it is present in larger amount and salt is solute as salt is present in smaller amount.

Solutions can be classified into three types: Solid solution, gasesous solution and liquid solution.

Solid Solid Solution

When both the component in a solution are solids, then solution is called solid-solid solution. For Example: alloys.

Alloys

An alloy is made by mixing of two more solids. These solids may be metals or non-metals. Alloys are the Examples of solid solution.

Example: Brass. Brass is a mixture of about 30% of zinc and 70% of copper.

Stainless steel: Stainless steel is an alloy of steel and with a minimum of 10.5% of chromium. Stainless steel is also known as INOX STEEL or INOX. Inox came from a French word inoxydable (inoxidiable).

Bronze: Bronze is an alloy of copper and tin. Bronze is generally made by mixing o 88% of copper and 12% of tin. However, in addition to copper and tin other metals such as aluminium, manganese, nickel or zinc, etc are added sometimes to make the property of bronze different.

Gas-Gas Solution

When both of the components of a solution are gas, then solution is called Gas-Gas Solution. For Example: Air.

Air

Air consists of many gases. Air consists of mainly oxygen, carbon dioxide and nitrogen and other many gases. Hence air is an Example of gaseous solution.

Solid-Liquid Solution

Tincture of Iodine

Tincture of iodine is an Example of solution. Tincture of iodine is a homogeneous mixture of iodine and alcohol. In this solution, iodine is solute as it is present in smaller amount and alcohol is solvent as it is present in larger amount.

Thus tincture of iodine and salt solution in water are the Example of solid-liquid solution.

Salt solution in water, sugar solution in water, etc. are the Examples of solid liquid solutions.

Gas-Liquid Solution

When one component of a solution is gas and other is liquid, then solution is called gas liquid solution.

Aerated drinks like soda water etc, are Examples of gas in liquid solution.

Properties of a Solution

A solution is a homogeneous mixture.

The particles of a solution are smaller than 1 nm(10^–9 metre) in diameter. Since particles of a solution are very small in size, thus they cannot be seen by naked eyes.

A beam of light is not scattered when passed through a solution. This is because particles of solution are very small, i.e. microscopic in size, hence they do not scatter the beam of light. And hence path of light is not visible in a solution.

The solute particles of a solution cannot be separated though the process of filtration.

The solute particles of a solution do not settle down when left undisturbed. This is the cause that a solution is stable.

Saturated and Unsaturated Solution

A solution may be saturated or Unsaturated.

Saturated Solution

At any particular temperature, a solution that has dissolved as much solute as it is capable of dissolving, is said to be a SATURATED SOLUTION.

In other words, when no more solute can be dissolved in a solution at a given temperature, then the solution is called SATURATED SOLUTION.

Unsaturated Solution

If the amount of solute contained in a solution is less than the saturated level, it is called an UNSATURATED SOLUTION.

In other words, if the amount of solute contained in a solution is less than the capacity of dissolving, the solution is said to be Unsaturated Solution.

Solubility:

The amount of solute present in a saturated solution at a given temperature is called the SOLUBILITY of the solution.

Dilute and Concentrated Solution

Dilute and concentrated are the relative or comparative terms.

The relative proportion of the solute and solvent can be varied.

Concentration of a solution depends upon the amount of solute present in a solution. A solution can be called dilute, concentrated or saturated depending upon the amount of solute present in a solution.

If there are two same solutions, and one solution contains less amount of solute than other, then solution which has larger amount of solute will be called concentrated and that which has lesser amount of solute will be called dilute solution.

If we take a salt solution in water. Put it in two test tubes. And mix some water in one test tube, then this solution will be called dilute and that one in which water has not been added will be called concentrated solution.

Concentration of A Solution

The amount of solute present in a given amount of solution, or the amount of solute dissolved in a given mass or volume of solvent, is called CONCENTRATION.

Concentration of solution `=(text{Amount of solute })/ (text{Amount of solution})`

Or, Concentration of solution `=(text{Amount of solute })/ (text{Amount of solvent})`

Concentration of a solution can be expressed in various ways. Two important ways to express concentration are Mass by mass percentage and Mass by volume percentage.

(i) Mass by mass percentage of a solution `=(text{Mass of solute})/(text{Mass of solution})xx100`

(ii) Mass by volume percentage of a solution `=(text{Mass of solute})/(text{Volume of solution})xx100`

Calculation of Concentration of a Solution

Example: 1. A solution contains 50g of common salt in 400 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.

Solution:

Given, Mass of solute (salt) = 50 g

Mass of solvent (water) = 400 g

We know that Mass of solution = Mass of solute + Mass of solvent

Thus, mass of the given solution = 50 g + 400 g = 450 g

And we know that,

Mass by mass percentage of a solution `=(text{Mass of solute})/(text{Mass of solution})xx100`

Thus, Mass percentage of the given solution

`=(50\ g)/(450\ g) xx100`

`=1/9 xx 100 = 11.11%`

Thus, mass by mass percentage of given solution = 11.11%

Example: 2. A solution contains 50g of sugar in 200 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.

Solution:

Given, Mass of solute (sugar) = 50 g

Mass of solvent (water) = 200 g

We know that Mass of solution = Mass of solute + Mass of solvent

Thus, mass of the given solution = 50 g + 200 g = 250 g

And we know that,

Mass by mass percentage of a solution `=(text{Mass of solute})/(text{Mass of solution})xx100`

Thus, Mass percentage of the given solution

`=(50\ g)/(250\ g) xx100`

`=1/5 xx 100 = 20%`

Thus, mass by mass percentage of given solution = 20 %