SolutionsBy: Cash Li

What is a solution?A solution is a homogeneous mixture of two or

more substances on a single physical state. In a solution, the solute is dispersed uniformly

throughout the solvent.

How it form?1. Solvent molecules attracted to surface ions.2. Each ion is surrounded by solvent molecules.3. Enthalpy (DH) changes with each interaction broken

or formed.

Properties of a solution1. The particles in a solution are very small2. The particles in a solution are evenly

distributed or intermingled uniformly on a molecular level.

3. The particles in a solution will not separate no matter how long the solution is allowed to stand under constant conditions

Solute v. SolventA solute is the substance that dissolves

In a lemonade the sugar is a solute Solvent is the substance that does the

dissolving Water is a solvent and it is known as the

universal solvent

Soluble A substance that dissolves in another

substance is said to be soluble.Also a substance is soluble also means that it

is capable of being dissolved.

Factors affecting solubilityThe stronger the intermolecular

attractions between solute and solvent, the more likely the solute will dissolve.

like dissolves like:Polar substances tend to dissolve in polar

solvents.Nonpolar substances tend to dissolve in

nonpolar solvents

Solubility Curve

Solubility Curve Cont. The solubility curve is the most helpful tool in

the reference table that will find the saturation, and solubility of the given substances.

How to use the curve:1. The line of each substances show their

soluble points or their saturation points.2. If number falls above the line then it is super

saturated and there will be precipitants.3. If the number falls below the line then it is

unsaturated and no precipitants will fall.

Types of Solution Solid Solution

They are formed by melting the component metals, mixing them together and then allowing them to cool

Gas If the solvent is a gas, only gases are dissolved under

a given set of conditions. An example of a gaseous solution is air (oxygen and other gases dissolved in nitrogen). Since interactions between molecules play almost no role, dilute gases form rather trivial solutions. In part of the literature, they are not even classified as solutions, but addressed as mixtures.

Types of Solution cont.Liquid

Miscible This means that the liquids of two different substances mix

well together. Immiscible

Two different substances will no mix well together. Ex: water and oil

Aqueous An aqueous solution is a solution in which the solvent is

water. It is usually shown in chemical equations by appending (aq) to the relevant formula, such as NaCl (aq). The word aqueous means pertaining to, related to, similar to, or dissolved in water.

Concentration of SolutionsThe concentration of a solution is the amount

of solute in a given amount of solvent or solution

Concentration MolarityMolality

Molarity The number of moles of solute dissolved on

each liter of solution.Equation

M = m/LAlso volume is temperature dependent, so

molarity can change with temperature change.

Molality The number of moles of solute dissolved in

each kilogram of solventEquation

Molality = mole of solute/ kilogram of solvent

Mole Fraction Equation

Mole fraction = moles of components/total moles of solution

In some applications, one needs the mole fraction of solvent, not solute—make sure you find the quantity you need!

SaturationSaturated solution

Solvent holds as much solute as is possible at that temperature.

Undissolved solid remains in flask.Dissolved solute is in dynamic equilibrium with

solid solute particles

Saturation cont.Unsaturated Solution

Less than the maximum amount of solute for that temperature is dissolved in the solvent.

No solid remains in flask.

Saturation cont.Supersaturated

Solvent holds more solute than is normally possible at that temperature.

These solutions are unstable; crystallization can often be stimulated by adding a “seed crystal” or scratching the side of the flask.

Finished