Unit 1, Section C.1

In which you will learn about:•Solutions•Electrolytes•Saturation

•Solubility curves

Some DefinitionsSome DefinitionsA solution is a A solution is a

homogeneous homogeneous mixture mixture of 2 or more substances of 2 or more substances in a single phase. in a single phase.

One constituent is usually One constituent is usually regarded as the regarded as the SOLVENTSOLVENT and the and the others as others as SOLUTESSOLUTES..

Parts of a Solution• SOLUTE – the part of

a solution that is being dissolved (usually the lesser amount)

• SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)

• Solute + Solvent = Solution

Solute Solvent Example

solid solid Metal alloys

solid liquid Salt water

gas solid Moth balls

liquid liquid Alcohol in water

gas liquid soda

gas gas air

DefinitionsDefinitions

Solutions can be classified as Solutions can be classified as saturatedsaturated or or ununsaturatedsaturated..

A A saturatedsaturated solution contains the solution contains the maximum quantity of solute that maximum quantity of solute that dissolves at that temperature.dissolves at that temperature.

An An unsaturatedunsaturated solution contains solution contains less than the maximum amount less than the maximum amount of solute that can dissolve at a of solute that can dissolve at a particular temperatureparticular temperature

Example: Saturated and Unsaturated Fats

Unsaturated fats have at least one double bond between carbon atoms; monounsaturated means there is one double bond, polysaturated means there are more than one double bond. Thus, there are some bonds that can be broken, chemically changed, and used for a variety of purposes. These are REQUIRED to carry out many functions in the body. Fish oils (fats) are usually unsaturated. Game animals (chicken, deer) are usually less saturated, but not as much as fish. Olive and canola oil are monounsaturated.

Saturated fats are called saturated because all of the bonds between the carbon atoms in a fat are single bonds. Thus, all the bonds on the carbon are occupied or “saturated” with hydrogen. These are stable and hard to decompose. The body can only use these for energy, and so the excess is stored. Thus, these should be avoided in diets. These are usually obtained from sheep and cattle fats. Butter and coconut oil are mostly saturated fats.

DefinitionsDefinitions

SUPERSATURATED SOLUTIONSSUPERSATURATED SOLUTIONS contain more solute than is possible contain more solute than is possible to be dissolvedto be dissolved

Supersaturated solutions are unstable. Supersaturated solutions are unstable. The supersaturation is only The supersaturation is only temporary, and usually accomplished temporary, and usually accomplished in one of two ways:in one of two ways:

1.1. Warm the solvent so that it will Warm the solvent so that it will dissolve more, then cool the solution dissolve more, then cool the solution

2. Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

SupersaturatedSupersaturatedSodium AcetateSodium Acetate

• One application of a One application of a supersaturated supersaturated solution is the solution is the sodium acetate sodium acetate “heat pack.”“heat pack.”

IONIC COMPOUNDSIONIC COMPOUNDSCompounds in Aqueous SolutionCompounds in Aqueous Solution

Many reactions involve ionic compounds, Many reactions involve ionic compounds, especially reactions in water — especially reactions in water — aqueous solutions.aqueous solutions.

KMnOKMnO44 in water in water KK++(aq) + MnO(aq) + MnO44--(aq)(aq)

How do we know ions are How do we know ions are present in aqueous solutions?present in aqueous solutions?

The solutions The solutions conduct conduct electricityelectricity

They are called They are called ELECTROLYTESELECTROLYTES

HCl, MgClHCl, MgCl22, and NaCl are , and NaCl are strong electrolytesstrong electrolytes. . They dissociate completely (or They dissociate completely (or nearly so) into ions.nearly so) into ions.

Aqueous SolutionsAqueous Solutions

Aqueous Aqueous SolutionsSolutions

Some compounds dissolve in Some compounds dissolve in water but do not conduct water but do not conduct electricity. They are called electricity. They are called nonelectrolytes.nonelectrolytes.

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

It’s Time to Play Everyone’s Favorite Game Show… Electrolyte or Nonelectrolyte!

Electrolytes in the BodyElectrolytes in the Body

Carry messages to Carry messages to

and from the brain and from the brain

as electrical signalsas electrical signals

Maintain cellular Maintain cellular

function with the function with the

correct correct

concentrations concentrations

electrolyteselectrolytes

Make your ownMake your own

50-70 g sugar50-70 g sugarOne liter of warm waterOne liter of warm waterPinch of saltPinch of salt200ml of sugar free fruit 200ml of sugar free fruit

squashsquashMix, cool and drinkMix, cool and drink

THANK YOU!

• The remainder of this powerpoint presentation was borrowed from

library.tedankara.k12.tr/IB/mustafa/AQUEOUS%20SOLUTIONS.ppt

Solubility curve

Saturated

Unsaturated

Supersaturated

Solubility curve

• Any point on a line represents a saturated solution.

• In a saturated solution, the solvent contains the maximum amount of solute.

• Example• At 90oC, 40 g of NaCl(s) in 100g

H2O(l) represent a saturated solution.

Solubility curve• Any point below a line

represents an unsaturated solution.

• In an unsaturated solution, the solvent contains less than the maximum amount of solute.

• Example• At 90oC, 30 g of NaCl(s) in

100g H2O(l) represent an unsaturated solution. 10 g of NaCl(s) have to be added to make the solution saturated.

Solubility curve• Any point above a line

represents a supersaturated solution.

• In a supersaturated solution, the solvent contains more than the maximum amount of solute. A supersaturated solution is very unstable and the amount in excess can precipitate or crystallize.

• Example• At 90oC, 50 g of NaCl(s) in 100g

H2O(l) represent a supersaturated solution. Eventually, 10 g of NaCl(s) will precipitate.

Solubility curve

Any solution can be made saturated, unsaturated, or supersaturated by changing the temperature.