SolutionsSolutions

A story of homogeneous A story of homogeneous mixtures, their properties and mixtures, their properties and

characteristics.characteristics.

SolutionsSolutions

• We are going to We are going to look at the look at the characteristics of characteristics of how sugar how sugar dissolves in some dissolves in some water. This is a water. This is a typical solution.typical solution.

SUGAR WATER SOLUTIONSUGAR WATER SOLUTION

• Individual sugar Individual sugar molecules break molecules break apart from the solid apart from the solid and enter the and enter the solution.solution.

• Actual molecules can Actual molecules can NOT be seen, we will NOT be seen, we will use the dots to use the dots to represent dissolved represent dissolved sugar molecules.sugar molecules.

Characteristics of solutions:Characteristics of solutions:

• Uniform concentration throughout.Uniform concentration throughout.

• Don’t settle out.Don’t settle out.

• Clear and transparent, could be Clear and transparent, could be colored.colored.

• Consists of a single phase.Consists of a single phase.

• Pass through filters because of tiny Pass through filters because of tiny particles.particles.

Solute dissolved in solventSolute dissolved in solvent

• The solvent does the The solvent does the dissolving and is in dissolving and is in the great quantity. the great quantity.

• The solute is The solute is dissolved and is in dissolved and is in the lesser quantity.the lesser quantity.

• In this example, In this example, sugar is the solute sugar is the solute and water is the and water is the solvent.solvent.

TYPES OF SOLUTIONS:TYPES OF SOLUTIONS:• Gas dissolved in a gas.Gas dissolved in a gas.

– Air is a good example, it is a mixture of Air is a good example, it is a mixture of nitrogen, oxygen and other gases.nitrogen, oxygen and other gases.

• Gas dissolved in a liquid.Gas dissolved in a liquid.– Carbonated beverages are good Carbonated beverages are good

examples, carbon dioxide gas dissolved examples, carbon dioxide gas dissolved in water.in water.

• Liquid dissolved in a liquid.Liquid dissolved in a liquid.– The antifreeze in your car’s radiator is a The antifreeze in your car’s radiator is a

mixture of ethylene glycol and water.mixture of ethylene glycol and water.

TYPES OF SOLUTIONS:TYPES OF SOLUTIONS:

• Solid dissolved in a liquid.Solid dissolved in a liquid.– There are many examples, such as There are many examples, such as

saline solution is a salt dissolved in saline solution is a salt dissolved in water.water.

• Aqueous solution.Aqueous solution.– Any solution that has water as the Any solution that has water as the

solvent.solvent.

RATE OF SOLUTIONRATE OF SOLUTION

• The rate of solution is how fast the The rate of solution is how fast the solute will dissolve in the solvent.solute will dissolve in the solvent.

• We will discuss four factors that We will discuss four factors that affect the rate of solution:affect the rate of solution:– TemperatureTemperature– Surface AreaSurface Area– PressurePressure– MotionMotion

What makes the solute dissolve What makes the solute dissolve faster?faster?• TemperatureTemperature: The higher the : The higher the

temperature, the faster the particles temperature, the faster the particles move. Therefore they can dissolve move. Therefore they can dissolve faster.faster.

• Surface AreaSurface Area: The greater the surface : The greater the surface area, the finer the particles are. This area, the finer the particles are. This allows more contact between the solvent allows more contact between the solvent and solute; hence a faster solution.and solute; hence a faster solution.

What makes the solute dissolve What makes the solute dissolve faster?faster?

• PressurePressure: Only affects gases, but : Only affects gases, but they will dissolve faster if the they will dissolve faster if the pressure is higher. pressure is higher.

• MotionMotion: Stirring or shaking will cause : Stirring or shaking will cause the particles to come in contact with the particles to come in contact with the solvent quicker, therefore the the solvent quicker, therefore the rate of solution increases.rate of solution increases.

How much is dissolved?How much is dissolved?• UnsaturatedUnsaturated: The solvent can dissolve : The solvent can dissolve

more solute.more solute.

• SaturatedSaturated: The solvent has dissolved : The solvent has dissolved as much solute as it can at the as much solute as it can at the temperature.temperature.

• SupersaturatedSupersaturated: More solute is : More solute is dissolved in the solvent than possible. dissolved in the solvent than possible. This is done by heating a solution and This is done by heating a solution and then letting it cool. This only works for then letting it cool. This only works for certain chemicals.certain chemicals.

How much is dissolved?How much is dissolved?

• DiluteDilute: Not much solute dissolved in : Not much solute dissolved in the solvent.the solvent.

• ConcentratedConcentrated: A lot of solute is : A lot of solute is dissolved in the solvent.dissolved in the solvent.

• Dilute and concentrated are Dilute and concentrated are relativerelative terms, not exact amounts.terms, not exact amounts.

Questions:Questions:• Can a dilute solution be saturated?Can a dilute solution be saturated?

– Yes. Some chemicals do not dissolve Yes. Some chemicals do not dissolve very much so they may become very much so they may become saturated with very little solute.saturated with very little solute.

• Can a concentrated solution be Can a concentrated solution be unsaturated?unsaturated?– Yes, concentrated is just a relative term, Yes, concentrated is just a relative term,

more solute might be able to be more solute might be able to be dissolved even a lot has dissolveddissolved even a lot has dissolved

Turn the worksheet over Turn the worksheet over and run the Solubility Curve and run the Solubility Curve

program.program.