science 7 discovering science 7

Science 7Discovering Science 7

Unit 3:Mixtures and Solutions

Chapter 7:Matter can be classified as mixtures

or pure substances

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.

States of Matter

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), ...

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, ...

Chapter 8:Some substances dissolve to form

solutions faster and more easily than others

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

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.

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.

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

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

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.

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

Which glass has the higher concentration of red dye?

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

Solubility

Factors which affect the solubility of solids and gas:

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

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

Chapter 9:Many useful products depend on

technology for separating mixtures and solutions

Separating “Heterogeneous” Mixtures

• Mechanical Sorting (280)FloatationMagnetism

Filtration

Separating “Homogeneous” Mixtures

• Evaporation(282)

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

• Paper Chromatography (284)

Petroleum and Gold

• Investigate how petroleum and gold are extracted and refines.

Petroleum (292-293)

Gold (294-296)