Solubility is defined as the maximum quantity of a substance that can be dissolved in another. A solution is formed when a solute dissolves evenly throughout a solvent, forming a homogeneous mixture. Not all substances are soluble - some like chalk or sand are insoluble in water and will not dissolve. The amount of a substance that can dissolve in a solvent at a given temperature is the solubility. Beyond this point, the solution is saturated. Water is a polar solvent that can dissolve many ionic compounds due to its positive and negative poles interacting with ions.

1. Solubility
and
Insolubility
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2. Solubility is defined as the maximum quantity of a
substance that can be dissolved in another.
The process of dissolving is termed dissolution.
In familiar cases, a solute is a solid (e.g., sugar, salt) and a
solvent is a liquid (e.g., water, chloroform), but the solute
or solvent might be a gas, liquid, or solid. The solvent can
either be a pure substance or a mixture.
.
Solubility is a measure of how well one substance
dissolves into another.

3. Soluble and Insoluble Substances
•The salt and copper sulfate are able to dissolve in water
because they are both soluble in water.
•Being soluble means that the water (solvent) is able to
completely separate the salt and copper sulfate (solute)
particles from each other.
•However, not all substance are soluble in water.
•For example, if chalk powder or some sand was added to
a beaker of water, no amount of stirring will get them to
dissolve.
•The chalk and sand are both insoluble in water.

4. •A solution is a mixture that is formed when a substance,
known as a solute, is dissolved in another substance,
known as a solvent.
•A solution is a homogeneous mixture.
•This means that it has a uniform composition throughout.
•The solute particles have dispersed evenly throughout
the solvent.

6. Saturated solution
A solution in which no more substance can be dissolved at a
given temperature is called saturated solution. A saturated
solution contains maximum amount of the substance which
can be dissolved in it at a given temperature.
For example, a maximum of 36 g of salt can be dissolved in 100
g of water at 20.C, so a saturated solution of salt at 20 . C
contains 36 g of salt dissolved in 100 g of water.

7. •Generally, the solubility of gases increases with pressure.
•For example, at 20 °C, the solubility of carbon dioxide in
water increases from 1.7 g/L at 1 atm to 15 g/L at 2 atm.
Carbonated drinks, such as soda water, contain carbon
dioxide gas that is forced into them under high pressure.
Cracking of knuckles is noisy. The gas carbon dioxide dissolves
in synovial fluid of the joints. It escapes due to low pressure
creating noise.

8. Types of Solutions
•You may think of solutions as being liquids, but they can
also be gases or solids.
•Similarly, solutes and solvent can be solids, liquids or
gases.
•Some examples of solutions that aren’t formed from a
solid dissolved in a liquid are listed below.
•A gas dissolved in a gas.
•Example: Entonox.
•Entonox is a mixture of nitrous oxide (laughing gas) and
oxygen, which is used for pain relief.
•A gas dissolved in a liquid.
•Example: hydrochloric acid.
•Hydrochloric acid is formed by dissolving hydrogen
chloride gas in water.
•A liquid dissolved in a liquid.
•Example: hydrogen peroxide solution.
•Hydrogen peroxide solution is formed by dissolving
hydrogen peroxide in water.

9. •A solid dissolved in a solid.
•Example: brass.
•Metal alloys, such as brass, are formed by combining two
metals, in this case copper and zinc; the metals are melted,
then mixed and cooled back to a solid. Five rupee coin has
nickel and zinc dissolved in copper.
•A liquid dissolved in a solid.
•Example: amalgam.
•Amalgam is a type of metal alloy where mercury, which is
a liquid, is combined with other metals, including silver, tin
and copper.
•Solutions may have more than one solute, and these may
be a mixture of solid, liquid and gas.
•For example, soft drink has many ingredients, including
sugar (solid), food colouring (liquid) and carbon dioxide
(gas), all dissolved in water.
teeth fillings are made
from silver-coloured
amalgam

10. Water: the Universal Solvent
One side of water is negatively charged because the oxygen
atom keeps the shared electrons longer than the hydrogen
atoms. As a result the
oxygen side is negatively charged
and the hydrogen side of water is positively charged.
O

11. Water: the Universal Solvent
Like a magnet that pulls on things that are magnetic, water pulls on things that are
electrically charged. Magnets have north & south poles, water has positive and
negative poles and thus called a polar solvent.
Since unlike charges attract, the negative end of water will be attracted to the positive
sodium ion. The positive end of water will be attracted to the negative chloride ion.
Since water is always in motion, it will pull on the ionic compound and move the ions
away from each other. This dissolves the ionic compound.
Na+ Cl-
The motion paths with some spin effects are good ways to show this concept.

12. Wax does not repel water
We’ve heard that wax or oils repel water. But that
isn’t true. Water is so attracted to other water
molecules that anything between them is squeezed
out of the way.
Oil
droplet Simple motion paths
with some spin
makes this concept
easier to understand.

13.  Do all substances dissolve in water?
 Why is it not possible to separate a solution through a
filter?
 How can the components of a solution be separated?
 Is there a limit to how much of a substance can be
dissolved in a given amount of water?
 Not all substances dissolve in water. Those that
dissolve are called soluble substances; those that do
not dissolve are called insoluble substances.
 Solutions cannot be separated by sieving, filtering,
hand sorting, or settling and decanting. This is
because solute particles are dispersed between the
solvent particles.
 Solutions can be separated by heating so that the
solvent evaporates. The dry solute will be left behind.