SolutionsSolutions

Classification of MatterClassification of MatterSolutions are homogeneous mixtures

SoluteSoluteA solute is the dissolved substance in a solution.

A solvent is the dissolving medium in a solution.

SolvenSolventt

Salt in salt water Sugar in soda drinks

Carbon dioxide in soda drinks

Water in salt water Water in soda

Types of Solutions

Solution – is a homogeneius mixture of substances in the same physical state. The substances are uniformly distributed. Can contain atoms, ions, or molecules.

Solid in Solid → Brass (zinc with copper) A.K.A. Alloy

Gas in Gas → Air

Liquid in Liquid → Alcohol in water

Solid in Liquid → Salt in water

Gas in Liquid → Soda (CO2 in Water)

A substance dissolved in water is known as an aqueous solution

Concentrated vs. DiluteConcentrated vs. Dilute

Concentrated- Having more solute particles per solvent particles.

Dilute – Having more solvent particles per solute particles.

Suspensions & ColloidsSuspensions & Colloids

Suspensions and Suspensions and ColloidsColloids

Suspensions and colloids are NOT solutions. Suspensions: The particles are so large that they settle out of the solvent if not constantly stirred.

Colloids: The particles intermediate in size between those of a suspension and those of a solution.

The Tyndall EffectThe Tyndall Effect

Colloids scatter light, making a beam visible. Solutions do not scatter light.

Which glass contains a colloid?

solutioncolloid

The ammeter measures the flow of electrons (current) through the circuit.

If the ammeter measures a current, and the bulb glows, then the solution conducts.

If the ammeter fails to measure a current, and the bulb does not glow, the solution is non-conducting.

Electrolytes vs. Electrolytes vs. NonelectrolytesNonelectrolytes

An electrolyte is:

  A substance whose aqueous solution conducts an electric current.

A nonelectrolyte is:

  A substance whose aqueous solution does not conduct an electric current.

Try to classify the following substances as electrolytes or nonelectrolytes…

Definition of Electrolytes and Definition of Electrolytes and NonelectrolytesNonelectrolytes

1.Pure water 2.Tap water 3.Sugar solution 4.Sodium chloride solution 5.Hydrochloric acid solution 6.Lactic acid solution 7.Ethyl alcohol solution 8.Pure sodium chloride 9.

Electrolytes?Electrolytes?

ELECTROLYTES: NONELECTROLYTES:

  Tap water (weak)

  NaCl solution

  HCl solution

  Lactate solution (weak)

 

  Pure water

  Sugar solution

  Ethanol solution

  Pure NaCl

But why do some compounds conduct electricity in solution while others do not…?

Answers to Electrolytes

Dissolution of sodium Dissolution of sodium ChlorideChloride

How Ionic solids dissolveHow Ionic solids dissolve

H HOH

H OH

HO

H HO

HHO

HH

O

HH

OH

H

O

HH

O

Rules for Determining SolubilityRules for Determining SolubilityTable GTable G

1. Determining Solubility:• Saturated Solution → Point is on the line• Unsaturated Solution → Point is below the line• Supersaturated Solution → Point is above the line

2. Interpreting the graph table G•Units on the graph are grams of solute/100g of water. •If problem calls for g/200g of water or g/50g of water, double or half the grams of solute, respectively.

Ex. 50g/100g of water 25g/50g of water 100g/200g of water 150g/300g of water

SolubilitySolubility

Practice ProblemsPractice Problems

1.1. How many grams of NaCl are needed to make a How many grams of NaCl are needed to make a saturated solution at 60˚C?saturated solution at 60˚C?

2. How much NaNO3 is required to make a saturated 2. How much NaNO3 is required to make a saturated solution in 100g of water at 60˚C? In 200g of water at solution in 100g of water at 60˚C? In 200g of water at 6060ººC?C?

3. How much KNO3. How much KNO3 will precipitate out of solution when a will precipitate out of solution when a saturated solution of KNO3 is cooled from 70˚C to 10?saturated solution of KNO3 is cooled from 70˚C to 10?

4. At 60˚C what type of solution is 35g of KNO3 in 100g of 4. At 60˚C what type of solution is 35g of KNO3 in 100g of water? In 50g of water? water? In 50g of water?

Solubility ChartSolubility Chart

Saturation of SolutionsSaturation of Solutions A solution that contains the maximum A solution that contains the maximum

amount of solute that may be dissolved amount of solute that may be dissolved under existing conditions is under existing conditions is saturatedsaturated. .

A solution that contains less solute than A solution that contains less solute than a saturated solution under existing a saturated solution under existing conditions is conditions is unsaturatedunsaturated. .

A solution that contains more dissolved A solution that contains more dissolved solute than a saturated solution under solute than a saturated solution under the same conditions is the same conditions is supersaturatedsupersaturated..

Saturation and EquilibriumSaturation and Equilibrium

Solubility TrendsSolubility Trends The solubility of MOST solids The solubility of MOST solids

increases with temperature. increases with temperature. The rate at which solids dissolve The rate at which solids dissolve

increases with increasing surface increases with increasing surface area of the solid. area of the solid.

The solubility of gases decreases The solubility of gases decreases with increase in temperature. with increase in temperature.

The solubility of gases increases The solubility of gases increases with the pressure above the with the pressure above the solution.solution.

Therefore…Therefore…Solids tend to dissolve best when:

o Heated o Stirred o Ground into small particles

Liquids & Gases tend to dissolve best when:

o The solution is cold o Pressure is high

Heat of SolutionHeat of SolutionThe Heat of Solution is the amount of heat energy absorbed (endothermic) or released (exothermic) when a specific amount of solute dissolves in a solvent. Table I

SubstancSubstancee

Heat of Heat of Solution Solution

(kJ/mol)(kJ/mol)NaOHNaOH -44.51-44.51

NHNH44NONO33 +25.69+25.69

KNOKNO33 +34.89+34.89

HClHCl -74.84-74.84

MolarityMolarity

The concentration of a solution measured in moles of solute per liter of solution.

mol = M L

MolalityMolality

The concentration of a solution in moles of solute per kilogram of solvent.

Since the most common solvent, water, has a density of 1 kg/L, one kilogram of water is the same as one liter of water!

mol = mm kg

Mass Percentage, ppm, and ppb• All methods involve quantifying amount of solute per

amount of solvent (or solution).• Generally amounts or measures are masses, moles or

liters.• Qualitatively solutions are dilute or concentrated.• Definitions:

Ways of Expressing Ways of Expressing ConcentrationConcentration

100solution of mass total

solutionin component of masscomponent of % mass

• Parts per million (ppm) can be expressed as 1 mg of solute per kilogram of solution. – If the density of the solution is 1g/mL, then 1 ppm = 1 mg

solute per liter of solution.

• Parts per billion (ppb) are 1 g of solute per kilogram of solution.

610solution of mass total

solutionin component of masscomponent of ppm

910solution of mass total

solutionin component of masscomponent of ppb