Solutions

Solutions

In this article we'll cover a crucial and a simple concept of chemistry referred to as Solutions.

Solutions are important to know how the  Solutions are formed and the way they behave. allow us to understand intimately what can we mean by the term “ Solution”.

A  Solution may be a homogeneous mixture of two or more solutes dissolved during a solvent. A solvent may be a substance during which a solute dissolves to supply a homogeneous mixture. A solute may be a substance that dissolves during a solvent to supply a homogeneous mixture. Usually the solvent is that the substance which is present within the greater amount than the solute. The word solution is usually used for the liquid state of matter. A typical example may be a saline where salt is that the solute dissolved in solvent water.

A solution exhibits many characteristics. a number of the important properties of solution are:

🡪A solution may be a homogeneous mixture.

🡪A solution consists of one phase solid, liquid or gas.

🡪Components during a solution can't be simply separated employing a mechanical filter.

🡪The particles present within the solution can't be seen with the naked eyes.

🡪The solutions don't affect the sunshine beam.

Concentration of an Solution

The concentration of a Solution is given by the quantity of solute present within the given solution. during a given solution the proportion of solute and solvent aren't equal. counting on the proportion of solute an Solution are often classified into three types.

1) Diluted solution

2) Concentrated solution

3) Saturated solution

1) Diluted solution: 

A dilute solution may be a sort of solution during which little amount of solute is present within the great deal of solvent. Therefore this solution is known as as dilute solution.

2) Concentrated solution: 

A concentrated solution is that the one during which the solute is present quite the solvent during a given solution. because the concentration of the solute is more it's named as concentrated solution.

3) Saturated solution: 

A saturated solution may be a quite solution during which maximum concentration of solute is dissolved within the solvent. No more additional solute are often dissolved during a saturated solution. because the solution is saturated it's referred to as saturated solution.

Buffer Solution

Buffers are the solutions which will resist in change of Ph on dilution and also it can resist on adding small amounts of acids or alkali.

These are extremely useful to take care of constant Ph value as there are tons of biological and chemical reactions that needs a continuing pH for the reaction to proceed.

Due to this solution the pH value won't change because it would be with a Solution that's not a buffer.

Types of Buffer Solution:

There are mainly two sorts of buffer solution:

Acidic Buffer

Alkaline Buffer

Acidic Buffer:

These are the solutions which have pH value below 7 which contain a weak acid and one among its salts.

A mixture of ethanoic acid and sodium acetate acts as a solution with a pH of 4.75

Alkaline Buffer:

These have pH value above 7 and contain weak base and one among its salts.

For example a mix of sal ammoniac and ammonia water acts as a solution with pH value of about 9.25

Preparation of Buffer Solution:

Buffer are often prepared either by mixing a weak acid with its conjugate base or weak base with its conjugate acid.

Image result for formation of solution

Suppose if you recognize the pKa (acid dissociation constant) of acid and pKb (base dissociation constant) of the bottom then you'll make a buffer of pH by controlling the ratio of salt and acid or salt and base.

Buffer Action:

The property of a Solution to resist any change in pH value when alittle amount of acid or the bottom is added thereto is understood as buffer action.

Working of Buffer Action:

For example let us take a mixture of acetic acid (CH3COOH) and sodium acetate (CH3COONa).

Here, the acetic is weakly ionized while sodium acetate is almost ionized.

CH3COOH   H+ + CH3COO–

CH3COONa   Na+ + CH3COC–

Here if you add a drop of strong acid like HCl, the H+ ions combine with CHCOO– and give CHCOOH and due to this there will be a slight change in its pH value.

CH3COOH + OH–    CH3COO– + H2O

Now if you add a drop of NaOH the OH– ions react with the free acid to give undissociated water molecules.

Due to this the OH– ions of NaOH are removed and the value of pH will not change.

Uses of Buffer Solution:

1. It is wont to regulate the pH of animal blood (it regulates the utilization of bicarbonate and acid buffer system).
2. It is also wont to maintain an optimum pH for enzyme activities in many organisms.
3. The absence of those buffers may cause slowing enzyme action or maybe denature of enzymes. This process can permanently deactivate the catalytic action of enzymes.

Raoult’s Law

Raoult’s Law was introduced by a french scientist Francois Marie Raoult within the year 1880.

This law of Thermodynamics states that the vapour pressure decreases when a substance gets dissolved during a solution.

Mathematical expression for Raoult’s law is given by:

p(i)= p(i)*x(i)

Where,

p(i) is the partial pressure,

p(i)* is the vapor pressure

x(i) is the mole fraction

Question arises on the way to calculate Total vapour pressure is that the combination of vapour pressure and dalton’s law. this is often when the Solution touches an equilibrium state.

The equation for this is often given by:

p= p(A)*x(A)+ p(B)+x(B)…………………….

Raoult’s law depends on the subsequent factors:

1. The vapour pressure of pure solvent
2. The mole fraction of the quantity of solute present during a substance.

Now, allow us to get into the perfect and non-ideal solutions and check out to differentiate between these.

Note: Please note that this law is applicable just for ideal solutions as these contains mixing ideal mixtures i.e.for pure substances.

This is represented by a graph as shown below.

Let us see the working of Raoult’s Law:

The vapour pressure of a solute decreases on adding a solute by occupying the gap in between the particles of a solvent.

There also are certain disadvantages of Raoult’s law:

1. We can apply this law on dilute solutions only.
2. This is also not applicable for those solutes or substances that associate or dissociate.

Van’t Hoff factor

A Dutch Scientist introduced the concept of Van’t Hoff factor to review the abnormalities in molar masses. The association and dissociation of a solute is understood by this factor.

Van’t Hoff factor is denoted by symbol “i”.

Combining of two particles is association. On the opposite hand, splitting of two particles is dissociation.

The major difference between these two is that:

In association i value is a smaller amount than one whereas in dissociation, it's greater than one.

For a non-electrolyte, i is adequate to one.

Formula to calculate van’t Hoff factor is given by:

i= observed colligative property/theoretical colligative property

Having said this, there's relations between Van’t Hoff factor and association of particles. Similarly, there's also a relation between Van’t Hoff factor and therefore the parameter (alpha) within the case of dissociation is given by:

These are just a few basic points to recollect . There are differing types of questions which are being asked from this subject .

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