VIDEO 1.4 Classifying Matter

Matter Anything that takes up space (has a volume) and has mass!

Substances A substance has a uniform and definite composition. Elements are the simplest form of matter which cannot be broken down chemically. They are listed by name on Table S. Compounds are made up of two or more elements that are chemically combined in a fixed ratio.

Mixtures A mixture is comprised of two or more substances. Homogeneous: a uniform mixture also known as a solution. You can not see its parts. Sometimes gets the symbol (aq) for aqueous which means dissolved in water. Heterogeneous: non uniform mixture. You can see the parts.

Mixtures Mixtures have two parts:  Solute: The substance(s) dissolving.  Solvent: The substance that does the dissolving. What is the “universal solvent”?

Element, Compound or Mixture? Iron Air Water (tap) Water (purified) Gold Methane Sand Sugar Iced tea Steel Chlorine Salt Soap Brass Sodium Calcium carbonate

Homogeneous or Heterogeneous?

Rules of thumb: If a single symbol, with one capitol letter is given or can be used to name the species, it is an element. If two or more combined symbols, with two more more capitol letters are given or can be used to name a species, it is a compound. All elements and compounds are homogeneous. If no chemical formula is given or can be found, it doesn’t have a fixed ratio and must be a mixture. These species can be homogeneous or heterogeneous.

Separating Mixtures There are many ways to separate a mixture. If it is heterogeneous, you many be able to just sort them with your hands. If not, you can use: 1. Decanting: The least accurate way to separate; you can pour off the top layer of liquid from the bottom layer. (You have probably done this at the beach with water and sand mixtures.)

2. Filtering: To separate a solid from a liquid, filter it using a funnel and filter paper. The solid stays on top, liquids pour through. (What happens if the solid is completely dissolved in the liquid?) Separating Mixtures

3. Distillation: When two or more liquids are mixed homogeneously, you can boil off each liquid separately using the following apparatus: This is how many water bottling companies clean their water.

Separating Mixtures 4. Chromatography: Mixtures can be dissolved and small samples can be placed on filter paper. The filter paper will be placed in a wet container, and the sample will rise to the top, separating each component out. This method is usually used to determine of the sample is pure or not. It is not used to completely separate the sample.

List observations for the solutions:

VIDEO 1.5 Phases

Solids Liquids and Gases

Solids Definite shape Definite volume Constant vibration Molecules are packed tightly in a geometric (crystalline) pattern

Liquids No definite shape Definite volume Constant motion No arrangement Molecules are closer together than a gas but further than a solid

Gases No definite shape No definite volume No arrangement Spread out Compressable

Pressure Gases exert a pressure on surrounding substances because they are constantly moving and colliding with other surfaces. Only in a vacuum, where there are no molecules, there is no pressure. Gas pressure can be measured in atmospheres or kilopascals, according to reference table A.

1. Which represents a liquid? Solid? Gas? 2. Which has the highest melting point? 3. Which has the weakest IMF? 4. Which has the lowest boiling point? 5. Which has the strongest IMF? 6. Which has a definite shape? 7. Which have a definite volume?

What is a vapor? Vapors are the gaseous form of a substance that is normally a liquid or solid at room temperature.

Heat transfers from areas of high to low temperature Endothermic reaction require you to put heat in. Exothermic reactions require you to take heat out; heat exits.

Phase Changes Identify the phase change and if it’s endothermic or exothermic: Evaporation Condensation Melting Freezing Sublimation Deposition Liquid to gas endothermic Gas to liquid exothermic Solid to liquid endothermic Liquid to solid exothermic gas to solid exothermic Solid to gas endothermic

Describe the following: Melting point Boiling Point Freezing Point MP and FP are the same Temperature for a pure substance since it uses the same phases!

Thermochemistry The study of energy changes that occur in chemical reactions.  Kinetic Energy refers to energy of motion. (Temperature)  Potential Energy refers to stored energy.

Phase Change Diagrams Where is the KE increasing? Where is the PE increasing? Where is KE stable? Where is the melting and boiling point?

1. Which line segment represents a liquid? A solid? 2. What is the boiling point? 3. What is the freezing point? 4. On what line segments is the PE increasing? 5. What is PE doing when it is not increasing? 6. Describe KE and PE. 7. Where is the solid/liquid equilibrium? 8. What would happen if it was heated further? B C E D A

Cooling Curve Identify the lines for solid, liquid and gas. Where is the KE decreasing? Where is the PE decreasing? Where is PE stable? Where is the melting and boiling point? B E D C A F

VIDEO 1.6 Changes in the Lab

Physical Changes require that the chemical not change composition. (Breaking, grinding, etc.) Chemical Changes require that the chemical changes into a new substance. (Burning, reacting, etc.)

Physical or Chemical Changes?

Observations Observations are made many ways. They can be either: Qualitative: appearance or behaviors: not measured Quantative: a mathematical description. and either Extensive: dependant on the amount of matter Intensive: dependant on type of matter

Qual or Quant and Intensive or Extensive? Rough or smooth Shiny or dull Large or small Kinetic energy

Classroom Slides

NameObservations Element Compound Homogeneous Mixture Heterogeneous Mixture Why? Copper Copper Sulfate Sand Magic Sand Magnesium Magnesium Nitrate Salt Sugar Soap Oil and Water Tap Water Purified Water

Hand in when finished : A student heats an unknown pure solid until it remains a gas and obtains the following data: 1. Draw and label a graph with time on the x axis and temperature on the y axis. 2. What is the freezing point? 3. What is the boiling point? 4. At what time do you first see a sign of the liquid phase? 5. At what time do you last see a sign of the liquid phase? 6. Explain what would happen if the student continued heating for another 30s. Time (s) Temp (C)