Classifying Matter

Pure Substances What is a Pure Substance? In a pure substance, all of the particles or molecules are the same. – Example: Water – all of the molecules in water are the same. Water is only made up of water molecules.

Mixtures of Substances What is a Mixture? A mixture contains at least 2 different types of particles/molecules. – Example: Air – Air contains nitrogen, oxygen and other gases.

Types of Mixtures Homogeneous - A mixture that has a uniform appearance and each portion contains the same properties and composition. – Examples: Milk, Air, Sugar Water, Blood. Heterogeneous - A mixture that does not have a uniform appearance and each portion does not have the same properties or composition. – Examples: Italian Dressing, Vegetable Soup, Granite.

Physical Properites Physical properties help us to describe or identify a substance. – Examples that we have examined include: Density Melting Point Boiling Point Specific Heat Capacity The physical properties of mixture depend on the physical properties of its’ components.

How can you separate a mixture of Sand and Water? Filtration – a technique that uses a porous barrier to separate a solid from a liquid. Used for separating solids from a liquid. Separating a Mixture (based on Physical Properties)

How can you separate a mixture of Salt and Water? Heat the sample to 100°C. The water will evaporate and the salt will remain in the container. Separating a Mixture (based on Physical Properties)

But what if you wanted to turn salt water into water that you can drink (pure water)? You would need to collect the water is evaporated and condense it. How can we condense water vapor? Distillation Separating a Mixture (based on Physical Properties)

Physical Properties of a Mixture Consider two samples. 1 test tube with water and 1 test tube with an equal amount of ethanol. Solubility of sugar

Physical Properties Cont. Water is soluble in sugar and is NOT soluble in ethanol. What if we mix the two samples together. How much sugar do you think will dissolve in the mixture? Solubility of sugar

Physical Properties Cont. Comparing the two densities of water and ethanol, what would you expect the density of an equal mixture to be.

Physical Properties Cont. Comparing the two boiling points of water and ethanol, what would you expect the boiling point of an equal mixture to be.

Draw a temperature vs. time graph for both water and ethanol WaterEthanol

Draw a temperature vs. time graph for both water and ethanol

Individual Particles/Molecules Mixture and Compounds Video Clip Compounds – “compounded atoms” are made when 2 or more different particles combine. – Iron Sulfide consists of “compounded atoms” of Iron and Sulfur. Elements – “elemental” or composed of only one kind of atom. – Iron and Sulfur are “elemental” because they are composed of only one kind of atom.