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solutions colloids suspensions

< 1 nm > 100 nm

transparent with Tyndall effect (scattering of light)

translucent(cloudy)

molecular motion movement by gravitycoagulation – can settlenever settle

transparent(clear)

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solutions colloids suspensions

< 1 nm > 100 nm

Tyndall Effect?

Passage of light Scattering in beam Scattering inall directions

Absorption of light

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Does a chemical reaction take place when one substance dissolves in

another?

No, dissolving is a physical

change because no new

substances are formed.

When one substance

dissolves in another,

the resulting mixture is

called a solution.

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Solutions

5Does a chemical reaction take place when one substance dissolves in another?

No, dissolving is a physical

change because no new

substances are formed.

When one substance

dissolves in another,

the resulting mixture is

called a solution.

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Some DefinitionsSome DefinitionsA solution is a A solution is a

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

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

HOMOGENEOUS

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Parts of a Solution

• The substance that is dissolved

• The substance present in a smaller amount

• The substance that dissolves the solute

• The substance that is present in the greater amount

• The solvent determines the state of the solution

Solute + Solvent = Solution

Solute Solvent

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“Like dissolves like”

–Polar dissolves in polar and ionic

Ex. Sugar and Water

–Non-polar dissolves in non-polar

Ex. oil and soap

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The solute breaks up into tiny particles that spread evenly throughout the solvent. In a solution of sugar water, sugar is the solute, and water is the solvent.

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Are all solutions liquids?

• No! Many types of solutions are possible. Let’s talk about a few examples.

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Alloy- a mixture done by the melting of two or more metals

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How do I get solutes to dissolve faster in solvents? Ex. Sugar in iced tea?Stir, and stir, and stir

Add temperature

Grind the solute to make it smaller

Fresh solvent contact and interaction with solute

Greater surface area, more solute-solvent interaction

Faster rate of dissolution at higher temperature

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• Definition: The maximum amount of solute that will dissolve in a given amount of solvent at a specified temperature and pressure.

• Soluble- the solute can be completely dissolved in the solvent

• Insoluble- the solute cannot be dissolved in the solvent. In fact, it separates completely.

SOLUBILITYSOLUBILITY

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Miscible vs. Immiscible

• When two liquids totally mix they are said to be miscible.

• When two liquids do not mix they are said to be immiscible.

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Dissolving process in water

Na+

Cl-

When particles of the solute are completely dispersed and surrounded by particles of the solvent, this process is called SOLVATION.

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Na+

Cl-

For water: POLAR-POLAR

For NaCl (s): ion-ion

For hydrated ion: Ion-polar

The separation of the ions in an ionic compound (usually by dissolving water) is called DISSOCIATION

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• The physical process of converting an atom or a compound into ions by adding or removing electrons. Usually done by a solvent in a solution.

IONIZATIONIONIZATION

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DefinitionsDefinitions

Solutions can be classified as Solutions can be classified as saturated or unsaturated.saturated or unsaturated.

A A saturated solutionsaturated solution-Contains -Contains the the maximummaximum quantity of quantity of solute that dissolves at that solute that dissolves at that temperature.temperature.

An An unsaturated solution-unsaturated solution-ContainsContains less than the less than the maximummaximum amount of solute amount of solute that can dissolve at a that can dissolve at a particular temperatureparticular temperature

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DefinitionsDefinitions

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

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

1.1. Warm the solvent then cool the Warm the solvent then cool the solution solution

2. Evaporate some of the solvent.http://www.youtube.com/watch?v=XSGvy2FPfCw

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SupersaturatedSupersaturatedSodium AcetateSodium Acetate

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

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

If the solution If the solution

conducts electricityconducts electricity it is called an it is called an ELECTROLYTEELECTROLYTE

Aqueous Solutions Aqueous Solutions (water is the solvent)(water is the solvent)

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Types of solutes

Na+

Cl-

Strong Electrolyte -100% dissociation,all ions in solution

high conductivity

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Types of solutes

CH3COOH

CH3COO-

H+

Weak Electrolyte -partial dissociation,molecules and ions in solution

slight conductivity

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Aqueous SolutionsAqueous Solutions

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

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

Examples include:Examples include:sugarsugarethanolethanolethylene glycolethylene glycol

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Types of solutes

sugar

Non-electrolyte -No dissociation,all molecules in solution

no conductivity

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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

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Concentration• The measure of how much solute is dissolved

in a specific amount of solvent or solution.

• Concentrated large amount of solute high Molarity

• Diluted small amount of solute low Molarity

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Percent by Mass

• The ratio of the solute’s mass to the solution’s mass expressed as a percent.

Percent by Mass = mass of solute

mass of solutionX 100

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Calculating Percent by mass

• What is the percent by mass of NaHCO3 in a solution containing 20 g NaHCO3 dissolved in 600 ml of H2O?

% mass NaHCO3

% mass = mass solute

mass solution

20 g NaHCO3 solute

600 ml H2O solvent

1 ml H2O = 1 g H2O 600 g H2O

X 100Formula

Given

Implied

% mass = 20g NaHCO3 620 g H2O

Unknown

X 100 = 3%

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Your turn

• You have been given 3.6 g NaCl that you then dissolve in 525 g of water. What would be the percentage by mass of NaCl?

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Molarity

• The number of moles of solute dissolved in per liter of a solution.

Molarity = moles of solute = mol

liters of solution LMolarity(M) = moles solute

liters of solution

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Calculating Molarity

• What is the molarity of an aqueous solution containing 40.0 g of glucose (C6H12O6) in a 1500 ml solution?

• If given 340 g of CuCl2, what would be the molarity of the solution if it was dissolved in 6425 cm3 of water? Note: (1 cm3 = 1 ml)

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molality

• Since the volume of a solution changes as temperature changes, the Molarity of the solution changes as well. Therefore, sometimes it is more useful to use molality.

Note 1 Kg= 1000 g

• Why? Because masses do not change with temperature!

Molality (m) = mol solute

kilograms solvent

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Calculating molality

• What is the molality of a solution containing 10.0 g Na2SO4 dissolved in 1000.0 g of water?

• What is the molality of a solution containing 30.0 g of naphthalene (C10H8) dissolved in 500.0 g of toluene?

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Practice Problems• Calculate the percent by mass of 3.55 g

NaCl dissolved in 88 g water.

• Calculate the percent by mass of benzene in a solution containing 14.2 g of benzene in 28.0 g of carbon tetrachloride.

• What is the molarity of the following solutions?– 15.25 g MgCl2 in 500 mL of solution

– 2.48 g CaF2 in 375 cm3 of solution

• Calculate the molality of the following solutions:– 20.0 g CaCl2 in 700.0 g H2O

– 3.76 g NaOH in 0.850 L H2O