Unit 3: Mixtures and Solutions Science 7 Unit 3: Mixtures and Solutions

Mixtures and Pure Substances Matter: Anything that has mass and takes up space. Four types: 1. Solid(table salt) 2. Liquid(water) 3. Gas(oxygen) 4. Plasma(stars)

Particle Theory of Matter All matter is made up of tiny particles. The particles are always moving – they have energy. There are spaces between the particles. There are forces of attraction between the particles. The particles of one substance are different from the particles of another substance.

Classification of Matter Matter is classified based on the type of particles it is made up of. There are TWO types: A) Pure Substances B) Mixtures: can be-Heterogeneous OR -Homogeneous

Pure Substance Matter that is made up of only one type of particle. Each part of the substance has the same properties. Examples include: Sugar, Table salt, Iron, Pure Water, Copper, Zinc, Oxygen, Carbon Dioxide, Gold. A pure substance always has the same properties because it is made up of the same type of particles. For example, sugar is composed of only sugar particles. Copper is composed of only copper particles.

Mixtures A combination of two or more types of matter that can be separated. Have more than one set of properties. -Example: Concrete is made up of different types/sizes/colors of rock. Made up of two or more types of particles. Each particle keeps its own properties. Examples include: Stainless steel pan, chocolate chip cookie, air, orange juice, ocean (salt water), concrete.

Comparing Pure Substances with Mixtures Types of Particles Properties Pure Substance 1 type Has the same properties throughout. Mixture 2 or more types Different particles keep their own properties.

Two Types of Mixtures 1. Heterogeneous Mixtures -A mixture made up of two or more parts that are visible to the eye (separate). -Each part of the mixture keeps its own properties. -Are also known as mechanical mixtures. -Examples include: Concrete , Chocolate chip cookie, Salad dressing, Granola cereal.

Two Types of Mixtures Continued 2. Homogeneous Mixtures -A mixture made up of two or more parts where the parts appear to be the same throughout. -Each part of the mixture combines so that the properties are the same throughout. -Are also know as solutions. -Examples Include: Stainless steel pan, Clean air, Salt water, Kool-aid.

Identifying Heterogeneous and Homogeneous Mixtures Type of Mixture Microscope Filtration (liquids only) Beam of Light Heterogeneous (mechanical) See two or more types of matter. Particles of substance caught on the filter paper. Light is scattered. Can see a beam of light in the mixture. Homogeneous (solution) See only one type of matter. No particles collected on the filter paper. Light is not scattered. Cannot see a beam of light passing through the mixture.

Pure Substance Vs Mixture (particles)

Combinations of Heterogeneous and Homogeneous Mixtures Many mixtures cannot be classified as either heterogeneous or homogeneous. They are combinations of both. Examples include: milk, orange juice, soft drinks.

Example 1: Milk Looks the same throughout (homogeneous). Contains fat droplets as seen under a microscope. Fat droplets are so small that it makes the milk look homogeneous. Fat is suspended in milk and makes it heterogeneous. Sugars are dissolved in milk, making it homogeneous.

Example 2: Orange Juice Sugars are dissolved in water making it a solution (homogeneous). Pulp in orange juice is easily seen making it a mechanical mixture (heterogeneous).

Solutions A homogeneous mixture. Two or more substances combine to form a mixture that looks the same throughout. Only one part can be seen. The particles of one substance are completely intermingled with the particles of another substance, so the mixture looks the same throughout. Solutions can be solid, liquid or gases.

Types of solutions Type of Solution Examples Solid Solutions (Alloys) 14-Karat Gold Brass Stainless Steel Pan Nickel Coin Liquid Solutions Seawater (salt water) Antifreeze Vinegar Apple Juice Gas Solutions Clean Air

Alloy A solid solution made up of two or more metals. Examples Include: -14-karat gold (58% gold, 42% other metals) -Brass (copper and zinc) -Nickel (nickel, copper, iron, carbon) -Stainless steel (iron, carbon, chromium)

Separating Mixtures and solutions Separating Heterogeneous Mixtures A) When you can easily see the different parts. Example 1: You can separate the raisins and flakes of Raisin Bran cereal by hand or by using tweezers. B) When you cannot easily see the different parts. Example 2: You can use a magnet to separate iron filings from a mixture of sand and iron filings.

Separating Mixtures and solutions Continued Mechanical Sorting -A way to separate parts of a mixture based on properties such as particle size and magnetism. Flotation (another type of mechanical sorting) -Depends of the density of the parts. -Some parts of the mixture will float while others may sink. -Example: Used to separate and skim the fat off soup.

Separating Mixtures and solutions Continued Filtration -Most common way to remove solid particles from a mixture. -Uses a filter device that has holes in it. -Holes in the filter can be large enough to see (like colander or window screen) or small enough that you need a magnifying glass to see them (like a tea bag or coffee filter). -How well the filter works depends on the size of its holes (holes must be smaller than the size of the particles you are trying to separate; if not they will just pass on through). -This is why filters cannot separate parts of a solution, the particles are smaller than the filter holes and will just pass right on through.

Separating Mixtures and solutions Continued Separating Homogeneous Mixtures/Solutions A) Evaporation - As you add heat to a liquid it will evaporate, separating the liquid part from the other part/parts of the solution. -Example: This is how maple syrup is made- sap is collected from trees, this sap is then boiled so the water in it evaporates, syrup is what is left after the evaporation occurs.

Separating Mixtures and solutions Continued B) Distillation -Example: Separating salt from water in order to make it clean and safe to drink. -Solution is heated until the liquid part changes state to become a gas (evaporation). -The gas then changes back to a liquid by cooling it (condensation). The liquid that condenses here is now free of the salt and is drinkable. -Because the rest of the solution does not change state (evaporate) it is left behind.

Separating Mixtures and solutions Continued C) Paper Chromatography -Example: Used in hospital labs to separate components of blood. The test results would show if a toxic chemical was present in a patients blood. -Used to separate colored substances in a mixture such as ink. -Works by seeing how fast a dissolved substance is carried through a material such as filter paper. -Different substances move at different speeds and form different patterns. -The speed and pattern of a substance will help in identifying what it is.