Solutions

Applied Chemistry 4.0

Background to Solutions A solution is a homogenous mixture that

has different substances dissolved in it that cannot be seen.This results in a single physical state.

Parts of a solution Solute: substance that is dissolved

…present in smaller amount

Solvent: substance that does the dissolving

…present in larger amount

Parts of a Solution

Solvent

Solute

Properties of Solutions

Small particles

Evenly distributed particles (uniform)

Particles will not separate when at rest

The ability to dissolve (solubility)

Dissolving Salt Animation

Background (cont.)

Soluble means something can be dissolved in something else.

Insoluble mean something cannot be dissolved in something else.

Dissolving a solid in a liquid can affect the boiling point and freezing point. This is called a colligative property.

Types of SolutionsSolid Solutions

Solid solution – final phase is solid

Alloys: Solid solutions containing two or more metals or a metal and a nonmetal

Advantages of alloys over pure metals: Stronger Cheaper More resistant to corrosion Lighter Harder

Examples of Alloys

Brass is an alloy of copper and zinc.

Steel is an alloy of carbon and iron.

Bronze is an alloy of copper and tin.

A closer look at alloys

Types of SolutionsGaseous and Liquid Solutions

Gaseous Solutions – final phase is gas Ex. Air

Liquid Solutions – final phase is liquid Miscible liquids: Can mix in all

proportions (ex. alcohol and water)

Immiscible liquids: Cannot mix in all proportions (ex. oil and water)

Miscible Liquids

Immiscible Liquids

Types of Solutions

Aqueous Solutions

Solutions with water as the solvent.

Because water can dissolve so many things, it is called the Universal solvent.

Electrolyte – a solution that conducts electricity.

Example of an electrolyte

Other types of solutions Tincture: Solutions with alcohol as the

solvent (ex – herbal medicines) A saline solution is a solution of salt and

water.The solute is salt.The solvent is water.

A dilute solution is a solution with little solute.

A concentrated solution is a solution with a lot of solute.

Concentration

A measure of the amount of solute in a solution.

% Concentration = mass of solute x 100 mass of solution

Usually used for concentrated solutions.

Example: Salt water is prepared by mixing 3g of salt with 97g of water. Calculate % concentration.

Mass of solute:

Mass of solvent:

Mass of solution: (solvent + solute)

% Con:

3 g

97 g (water)

100 g

3 x 100 = 3%

100

Dilution: to decrease the concentration by adding more solvent

Parts per million (ppm)-Usually used with dilute solutions.

One hundred or One thousand100 1000

One hundredth or One thousandth1/100 1/1000

One million or One billion1,000,000 1,000,000,000

One millionth or One billionth1/1,000,000 1/1,000,000,000

1 ppm 1 ppb

Parts per million

Sea water is a 3% solution.

Means: 3 grams of salt to 100 grams of sea water or 3 parts salt to 100 parts sea water

Looks like: 3/100 dilution(keep as a fraction)

ppm Examples

Food coloring is a 10% aqueous solution.

Means:10 grams of pigment to 100 grams of solution or 10 parts pigment to 100 parts of solution

Looks like: 10/100 dilution or 1/10 dilution

Parts per Million Lab Cup 1 contained a 10% solution or a 1/10

dilution of food coloring. What did you do for Cup 2?

1 drop from Cup 1 + 9 drops of water for a total of 10 drops

You made a 1/10 dilution of a 10% solution orYou made a 1/10 dilution of a 1/10 dilution

Looks like: 1/10 of 1/10 Means 1/10 x 1/10 = 1/100 In Cup 2, you have 1/100 dilution of food

coloring. In Cup 2, you have a 1/100 x 100 = 1%

concentration.

Other examples of ppm

1 ppm means 1 second in 12 days of your life.

1 ppm means 1 penny in $10,000.

1 ppm means one inch in 16 miles.

Solubility and the Dissolving Process Solubility is a physical property that gives

the # of grams of solute that will dissolve in a solvent (usually 100 g of water) at a given temperature & pressure

Saturated: A solution is saturated if it contains as much solute as can possibly be dissolved under existing conditions of temperature and pressure.

Unsaturated: Has less solute than the maximum amount that can be dissolved.

Supersaturated: Has more solute than the maximum amount that can be dissolved.

Unsaturated vs. Saturated Solution

Supersaturated Solutions

Three Factors Affecting the Rate of Dissolving

Surface Area – increases the number of collisions between the solute and solvent Sugar cube vs. sugar crystals

Stirring – increases the number of collisions between the solute and solvent. Stirring sugar in coffee/tea

Temperature – increases the energy of the collisions between the solute and solvent. Warm water vs. cold water

Solubility Graph for NaNO3

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Temperature (deg C)

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Saturated sol’n

Supersaturated solution

Unsaturated solution

At 20oC, a saturated solution contains how many grams of NaNO3 in 100 g of water?

What is the solubility at 70oC?135 g/100 g water

What kind of solution is formed when 90 g NaNO3 is dissolved in 100 g water at 30oC?

unsaturated

What kind of solution is formed when 120 g NaNO3 is dissolved in 100 g water at 40oC?

supersaturated

90 g

Solubility Graph for NaNO3

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Temperature (deg C)

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At 20°C, a saturated solution contains how many grams of NaNO3 in 100 g of water?

What is the solubility at 70oC?

What kind of solution is formed when 90 g NaNO3 is dissolved in 100 g water at 30oC?

What kind of solution is formed when 120 g NaNO3 is dissolved in 100 g water at 40oC?