How Chemicals Mix

Most Materials are Mixtures

• Mixture: a combination of two or more substances where each substance retains its own properties​

  • Most materials are mixtures​ of some sort

    • can contain elements, compounds or both

  • Examples of mixtures:

    • Atmosphere

    • Tap water

    • Soda

    • Adding Sugar/cream to coffee

  • Mixtures are a physical change

Mixtures can be separated by physical means

• The Components of a mixture can be separated by using the components physical properties

  • Filtration: means of separating a solid liquid relationship

  • Boiling/Evaporation

    • Removing salt/minerals from water

    • Distillation: Evaporating a liquid then condensing the vapor in another container

  • Melting

The classification of Matter

• Pure materials only contain a single element or compound

  • Pure gold is just Au, pure salt is NaCl

  • It is almost impossible to get a 100% pure substance, but we try to get as close as possible

• ​Impure material is a mixture of two or more compounds

Types of Mixtures-Heterogenous

• Heterogenous Mixtures: You can clearly distinguish the different parts of the mixture

  • Different parts of the mixture look different​

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Types of Mixtures-Homogenous

• Homogenous Mixture: You can't tell the different parts of the mixture apart

  • Every region looks the same

  • Two Types

    • Solution: all components are in the same state of matter

      • Atmosphere

    • Suspensions: Components are in different states of matter

      • Examples: Milk, Blood

      • Separated by a centrifuge

Making Solutions

• What Happens when you add sugar to water?

  • At first it dissolves and forms a homogenous mixture, also known as a Solution

    • Two parts of a Solution

      • Solvent: The larger amount of a solution

      • Solute: the smaller amount of a solution

    • Dissolving: the process of a Solute mixing with a solvent

      • Solute is what dissolves

  • Solutions can be in any state of matter​

Saturation of Solutions

• ​There are limits to how much can be dissolved in a solution

  • As you add more and more sugar to water, eventually some will just remain on the bottom of the container

• The amount of solute in a solution is described as saturation

  • Unsaturated Solution: Contains​ less solute than the maximum amount

  • Saturated Solution: Contains the exact amount of solute as the maximum amount

  • Supersaturates Solution: Contains more than the maximum amount of solute

Saturation of Solutions

Concentration and the Mole

• Concentration: The measurement of the the amount of solute in a solution

• In chemistry, we are more interested in the number of solute particles than the grams of solute

  • Particles are very small, so we use a special number to describe them

    • One Mole: ​6.02 x 10²³

      • Works similar to a dozen: one mole of donuts = 6.02 x 10²³

      • We use moles to describe atoms and particles because they are so small

        • Example: one mole of sugar weighs 342 grams

• Molarity: a measurement of concentration

  • M=Moles of solute/Liters of solution​

Solubility

• Solubility: The ability of a Solute to dissolve in a Solvent

  • Solubility depends on the attractions between solute particles

  • A material that does not dissolve is said to be insoluble

  • Different factors affect Solubility

    • Temperature:

      • In Liquids A higher temperature solution holds more solute

        • as solution cools, some of the solute precipitates out

      • In Gases Higher temperatures decrease the amount of solute held

    • Size of Solute: Smaller Solute particles dissolve quicker because more solute touches it

Soaps and Detergents

• Dirt and Grease combine and form a substance known as grime

  • Grime is a non-polar substance, and is hard to remove from skin and other objects

• Soaps are solutions that have both molar and non-polar properties, which allow them to grab onto grime