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Science 7 Discovering Science 7 Unit 3: Mixtures and Solutions

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Chapter 7: Matter can be classified as mixtures or pure substances

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Page 1: Science 7 Discovering Science 7

Science 7Discovering Science 7

Unit 3:Mixtures and Solutions

Page 2: Science 7 Discovering Science 7

Chapter 7:Matter can be classified as mixtures

or pure substances

Page 3: Science 7 Discovering Science 7

The Particles Theory

• All matter is made up of particles.• These particles are constantly moving – they

have energy.• There are spaces between these particles.• There attractive forces between the particles.• The particles of one substance differs from the

particles of other substances.

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States of Matter

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Matter

Pure Substances• A pure substance is matter

that is the same throughout; having the same kind of particles.

• Examples:Gold, copper water, iron, white sugar, ...

• The Period Table of Elements.

Mixtures• A mixture contains two or

more different types of matter; having different particles.

• Air (oxygen, carbon dioxide, nitrogen, etc.), garden salad (lettuce, tomatoes, carrots, etc.), Raisin bread (raisins, wheat, etc), ...

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Mixtures

Heterogeneous• Mechanical mixtures• Easy to see the different parts• Composition of particles varies

within the sample; more than one substance.

• Composition of samples may vary.

• Light will reflect perpendicular to the incident beam

• Examples: stir fry, sandwich,Salsa, ...

Homogeneous• Solution• Hard to see the different

particles; appears as one substance.

• Composition of particles is the same within the sample.

• Composition of samples is the same.

• Light will pass through unaffected.

• Examples: salt water, vinegar, clean air, ...

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Chapter 8:Some substances dissolve to form

solutions faster and more easily than others

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SolutionsCharacteristics of a Solution:• Dissolving• Solute• Solvent (Water,…)• Solubility (soluble/insoluble)

Page 10: Science 7 Discovering Science 7

Dissolving SubstancesWhen two substances mix together to create a solution, where one

substance dissolves into the other substance

Solute• Solvent is the substance

that dissolves.

Solvent• Solvent is the substance

in which the solute dissolves.

Page 11: Science 7 Discovering Science 7

Working with Solutions“Soluble” vs. “Insoluble”

Soluble Substances:• A substance that is “soluble” is able to

dissolve in a certain solvent.• Example: Sugar (a solute) is able to dissolve in

water. Water is considered the universal solvent.

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Insoluble Substances:• A substance that is “insoluble” is unable to

dissolve in a certain solvent.• Example: Sand is unable to dissolve in water.

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Qualitative and QuantitativeData and Description

Qualitative:The descriptive form when the relationship of solute to solvent is expressed using words.Ex. The jello solution turned orange when the jello powder was added.

Quantitative:The descriptive form when the relationship of solute to solvent is expressed with numbers.Ex. 3.4 g of jello powder to 2 cups of water.

Page 14: Science 7 Discovering Science 7

ConcentrationThe quantity (amount) of solute that is dissolved in a solvent.

• Concentrated Solution – Has a large mass of dissolved solute for a certain quantity of solvent.Example: Strong tea

• Dilute Solution – Has a small mass of dissolved solute for a certain quantity of solvent.Example: Light tea

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Which glass has the higher concentration of red dye?

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More of concentration

Saturated Solution• Forms when no more solute

will dissolve in a specific amount of solvent at a certain temperature.

• There will come a point when salt will not dissolve in water because the water is too saturated with salt.

Unsaturated Solution• Occurs when a solution is

able to dissolve more solute.

• Salt will continue to dissolve until it becomes saturated.

• Adding more solvent will dilute the solution, making the solute less in comparison to the solvent

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Solubility

Factors which affect the solubility of solids and gas:

• Stirring• Temperature• Pressure• Size of the particles of solute

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Measuring Concentration• Percent by mass

The simplest statement of the concentrations of the components of a mixture is in terms of their percentages by weight or volume. Mass percentage is calculated as the mass of a component divided by the total mass of the mixture, multiplied by 100%.

Ex. Bleach is 5.25% NaOCl by mass, which means each 100 g of bleach contains 5.25 g NaOCl.

• Parts per millionParts Per Million or ppm means out of a million. It describes the concentration of something in water or soil. One ppm is equivalent to one milligram of substance per liter of water (mg/l). Generally, used with low concentration.

Ex. 0.3 mg/l of salt

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Chapter 9:Many useful products depend on

technology for separating mixtures and solutions

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Separating “Heterogeneous” Mixtures

• Mechanical Sorting (280)FloatationMagnetism

Filtration

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Separating “Homogeneous” Mixtures

• Evaporation(282)

• DistillationSimple Distillation (283)Fractional Distillation (292-293)

• Paper Chromatography (284)

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Petroleum and Gold

• Investigate how petroleum and gold are extracted and refines.

Petroleum (292-293)

Gold (294-296)