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The following hypothesis refers to iron in the topsoil found on an island formed from limestone.

The following hypothesis refers to iron in the topsoil found on an island formed from limestone. Which study would most likely be used to investigate this hypothesis? A Tracking dust clouds with satellite photos B Determining the effects of iron on limestone

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The following hypothesis refers to iron in the topsoil found on an island formed from limestone.

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  1. The following hypothesis refers to iron in the topsoil found on an island formed from limestone. Which study would most likely be used to investigate this hypothesis? A Tracking dust clouds with satellite photos B Determining the effects of iron on limestone C Calculating erosion rates in African limestone mines D Analyzing the content of comet dust clouds

  2. A 54% * B 10% C 18% D 17%

  3. Practice of Sig Figs • How many sig figs in 2004? • How many sig figs in 0.0000033? • How many sig figs in 30170? • How many sig figs in 20.00? • How many sig figs in 3,000,000?

  4. Boiling water can be used to sanitize dishes. The data above show how sanitizing time varies in different locations. Which inference is supported by these data? F. The boiling point of water is constant at higher altitudes. G. The boiling point of water is affected by elevation. H. Water takes longer to boil at Fort Davis than at sea level. J. Boiling water changes temperature at a faster rate at Corpus Christi than at higher elevations.

  5. Unit 1 Matter Matter/Physical vs. Chemical Changes/ Law of Conservation of Mass

  6. Matter • Matter is anything that takes up space and has mass. • 3 phases of matter: • Solid • Liquid • Gas

  7. Solid • have a rigid structure. • resistant to changes of shape or volume. • does not take on the shape of its container

  8. Solids Shape: tightly packed particles; very ordered Volume: definite volume Compressibility: incompressible Examples: coal; sugar; ice

  9. Liquid • Like a gas, is able to flow and take the shape of a container. • Like a solid, it resists compression.

  10. Liquids Shape: less tightly packed, less order, take container’s shape. Volume: definite volume Compressibility: low compressibility Examples: water

  11. Gas • particles are widely separated from one another • takes the shape of a container.

  12. Gases Shape: particles far apart, no order Volume: indefinite volume Compressibility: very compressible Examples: air, oxygen, CO2

  13. Other States of Matter • PLASMA— an electrically charged gas; Example: the sun or any other star • BOSE-EINSTEIN CONDENSATE— a condensate that forms near absolute zero that has superconductive properties; Example: supercooledRb gas

  14. Phase Change Diagram Exothermic: Energy Decreasing Entropy Decreasing Endothermic: Energy Increasing Entropy Increasing Solid Deposition Melting Sublimation Freezing Vaporization Gas Liquid Condensation

  15. Energy Highest Energy           Lowest Energy Exothermic (exiting energy) Endothermic (entering energy)

  16. Entropy • Entropy is a measure of disorder. • The more order the particles have, the less entropic they are.

  17. Entropy Highest Entropy           Lowest Entropy Least Ordered           Most Ordered

  18. Phase Change Diagram Exothermic: Energy Decreasing Entropy Decreasing Endothermic: Energy Increasing Entropy Increasing Solid Deposition Melting Sublimation Freezing Vaporization Gas Liquid Condensation

  19. There are 3 Types of Chemical Energy: • Potential Energy: stored energy within a chemical structure. • Kinetic Energy: energy an object has because of its motion. • Thermal Energy: energy an object has because of its heat.

  20. The table shows the time it took trees of the same type and size to drop all of their leaves after being grown in different atmospheres. For the experiment to be valid, which of these must be a constant for all the trees? F. The height of all the trees during the entire experiment G. The amount of water available to all trees during the experiment H. The mass of fallen leaves collected from each tree J. The rate of photosynthesis in all trees during the experiment

  21. Energy , Entropy, and Phase Change Vaporization Condensation Energy Increasing Entropy Increasing Deposition Sublimation Melting Freezing

  22. Potential and Kinetic Energy and Phase Change PE = Potential Energy KE= Kinetic Energy KE PE KE PE KE

  23. Properties • How we identify substances!

  24. Properties • Chemical Properties: • Can be observed or measured when changing the composition of matter • Physical Properties: • Can be observed or measured without changing the composition of matter

  25. Chemical Properties: Do change the nature of matter. Chemical properties • Combustion • Reactivity with water • pH

  26. Physical Properties: Do not change the nature of matter. Intrinsic Properties: Properties that do NOT depend on the amount of matter present. • Color • Magnetism • Melting/Boiling Point • Density

  27. Physical Properties: Extrinsic Properties: Properties that DO depend on the amount of matter present. • Mass • Volume • Length

  28. Physical or Chemical Property? • Smell • Physical / intrinsic • Flammability • Chemical • Area • Physical/extrinsic • Reactivity • Chemical

  29. DENSITY • What is Density? • Density is the ratio of an object’s mass to its volume. Formula: D= Or: =

  30. Density in the Lab • In order to determine density in the lab; we must find the: Mass Volume

  31. Density in the Lab • Mass is determined on our electronic balances. • Units in grams. • Volume can be found in 2 ways: • With the formula l x w x h. • Units cm3 • Water displacement. • Units in mL (graduated cylinder)

  32. Finding Volume By Water Displacement Graduated Cylinder #1: 20.0 mL Graduated Cylinder #2: 23.0 mL Volume of rock: 3.0 mL

  33. DENSITY PRACTICE PROBLEMS: • Suzie obtained a graduated cylinder containing 35.0mL of water. After dropping a marble into the graduated cylinder, it now reads 45.7mL. If the marble’s mass is 15.50 g, what is the density of the marble? D=M/V 15.50g / 10.7 mL = 1.45 g/mL *** Round to the least # of sig figs! M=15.50g V=45.7mL-35.0mL=10.7mL

  34. DENSITY PRACTICE PROBLEMS • Martha’s jewelry box has a mass of 15.50 g. Its dimensions are 2.4cm x 5.6cm x 6.70cm. What is the density of this jewelry box? D=M/V 15.50g /90.cm3 = 0.17 g/cm3 *** Round to the least # of sig figs! M=15.50g V=2.4cm x 5.6cm x 6.70cm =90.cm3

  35. DENSITY • How is density related to an object’s ability to float? • If an object is LESS DENSE than a liquid, then it will FLOAT. • If an object is MORE DENSE than a liquid, then it will SINK.

  36. DENSITY- SINK OR FLOAT? • The standard density for water is 1.0 g/cm3. • Will the following objects sink or float in water? • A marble with a mass of 1.5g and a volume of 0.75mL. D= = 2.0g/mL; SINK • A wooden block with a mass of 0.5g and a volume of 1.0 cm3. D= = 0.5g/cm3;FLOAT

  37. A student is working with four beakers that each contain a clear liquid. Which set of procedures would be best to use to determine whether one of the beakers contains only distilled water? A C B D Observe odor Determine temperature Observe color Determine boiling point Observe volume Determine mass Observe color Determine pH Observe odor Determine pH Determine density Determine boiling point Determine mass Observe volume Determine temperature Observe odor

  38. A medical researcher hypothesizes that a • newly developed medication can reduce high blood pressure. Which of these would most likely be the dependent variable in a study involving this medication? • A The number of participants in the study • B The ages of people treated for high bloodpressure with other medications • C The blood pressure of the participants in • the study • D The number of people treated for high • blood pressure with other medications

  39. Formal Lab Report • Formal Lab Write Up for Chemistry • Write in blue or black ink on the front side of the pages. The back side of the page will not be graded. • Do not use liquid paper or tear out a page. • Place one line through mistakes – NO ERASING!

  40. Formal Lab • Label the sections of the report and write in the order shown below. • Be neat; skip a line between sections. • Write in complete sentences. • Follow specific instructions given for each lab reporting assignment.

  41. Format • LAB FORMAT: • Title • Date(s) • Objective or Statement of Problem • In future experiments, you will be asked to identify the variables (independent and dependent) involved. • Hypothesis • Materials

  42. Data • This section should contain an organized table with your data. • Your data should be well organized with units. • You should list any relevant qualitative observations. • Analysis • Calculations • You should neatly carry out your calculations for each trial. This means that you should label each calculation. • If you are using a formula, your calculations should include that formula. • Be sure to box your final answer. • Graphs • Your graphs should contain a title and labeled axes.

  43. Conclusion • Restate hypothesis. • Conclude whether you were right, wrong or uncertain. • Back up your conclusion by saying which data you used to reach that conclusion. Don’t just say “refer to Graph A”. Actually write the numbers, or whatever you have for data. You don’t have to repeat ALL the numbers – just the final ones. • If your hypothesis was not supported (a better word to use than “proven”) then identify possible sources of error (“human error” is not acceptable) or suggest a new hypothesis. • Discuss any problems with the procedure, for example. • Comment on what this experiment taught you, in a general sense.

  44. Bell Ringer In photography, which of these is an example of a chemical change? F Light being refracted by a camera lens G Adjusting a lens to focus light H Halide granules being activated by light J Allowing a certain wavelength of light into the camera

  45. Known Densities Group 1, 2 and 3 Group 4, 5, 6, and 7

  46. Physical Changes • Chemical composition remains the same. • Physical appearance or state of matter may change; but actual properties do not change. • Usually a reversible change.

  47. Examples of Physical Change: • Boil • Freeze • Crush • Dissolve • Melt • Bend • Condense • Split • Crack • Grind • Cut

  48. Chemical Changes • When a substance changes into a totally new substance. • The actual chemical composition is changed. • Cannot be easily reversed

  49. Indications of a Chemical Change: • Change in color or odor • Production of a gas (bubbles) • Energy released or absorbed (heat or light) • Formation of a precipitate (solid)

  50. Examples of Chemical Change: • Burn • Rot • Rust • Corrode • Explode • Decompose • Ferment

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