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A Look at Water and Its Contaminants

A Look at Water and Its Contaminants

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A Look at Water and Its Contaminants

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  1. A Look at Water and Its Contaminants

  2. Chemistry Concepts Covered • Physical Properties • Diff between evaporation and BP • Important Physical Properties of water • Density

  3. Chemistry Concepts Covered • Chemical Properties • Types of Mixtures • Chemical Formulas/Symbols • Electrical Nature of Matter • Ions • How to Write Ionic compounds

  4. Physical Properties of Water 1. What are physical properties of water or any other substances? • those characteristics shared by all samples of a substance w/o changing the substance

  5. Physical Properties of Water 2. What is the rarest and most unusual substance in the universe? Why? • water, very little water has been found in the planets of the solar system • water has very unusual properties for chemicals of its size and composition

  6. Physical Properties of Water 3. How much of the earth’s surface is covered by water? • 70%-water is the most common liquid on earth 4. Is water ever entirely pure? • No surface water has dissolved minerals in them, even distilled water has dissolved gases in them

  7. Examples of Physical Properties Color

  8. Examples of Physical Properties Is it a gas, liquid, or solid?

  9. Examples of Physical Properties taste odor length volume density

  10. Physical Properties of Water 5. What are the physical characteristics of water? • colorless, odorless, tasteless 6. But wait, some water have a definite taste, what about that, huh? • it is the dissolved stuff in water that can give it taste, odor, or even color

  11. Physical Properties of Water 8. What is density? • How much stuff or mass is crammed in a particular amount or volume of matter • Mass per volume or Mass / volume or g / mL 9. Give some examples of substances and their densities.

  12. Density: other examples Substance Density(g/cc) Oxygen gas .001331 Water 1.00 Ice .92 ethanol .79 Aluminum 2.70 Iron 7.87 Copper 8.96

  13. Density Two materials: styrofoam and brick. Same volume. Same mass?

  14. Density On the microscopic level you can clearly see that the brick is more closely bunched together. There is more brick atoms per volume than styrofoam. We say brick is more dense than styrofoam.

  15. Density • Density is defined as the mass of a substance per the volume of the substance • Mathematical formula D= M/V where D= Density, M=Mass(g), V=Volume(mL or L)

  16. Density • Ex. 1 A piece of lead has a mass of 22.7 g. It occupies a volume of 2.00 cc. What is the density of the lead?

  17. Density Ex.2 A piece of lead occupies a volume of 4.00 cc. What is the mass of the lead?

  18. Density 3. A piece of lead has a mass of 302 g. What is the volume of the lead?

  19. Density Mercury: the most dense liquid (13.55 g/cc) Gold: the most dense solid (19.32 g/cc)

  20. Physical Properties of Water 10. Rank the phases of matter in terms of most dense to least dense • most solids--> most liquid--> gas 11. What is a good example of an exception to number 10? • water

  21. Physical Properties of Water 12. Why is it so important that water is more dense than ice? • lakes and ponds freeze at the surface and not at the bottom where it would disrupt the food cycle

  22. Ice is less dense than water

  23. Physical Properties of Water 13. How does the Density of water cause erosion in nature? • rainwater seeps into cracks then expanding as it freezes cracking the rock or road even further

  24. Physical Properties of Water 14. Why is the boiling point and freezing point of water important to the way we measure temperature in Science? • the Celsius scale is attuned to it, water freezes at 0 and boils at 100˚C

  25. Physical Properties of Water 15. What is the difference between boiling and evaporation? • in both, liquid is turning to gas • evaporation occurs at any temperature even 0˚C, boiling takes place only at around 100˚C • evaporation only occurs at the surface, boiling takes place under the surface

  26. Physical Properties of Water 16. Can we see steam? • No, you cannot see steam, you can only see water vapor when millions of water gas have stuck together to form a tiny droplet, like in clouds

  27. Physical Properties of Water 17. What is it about the BP of water that is important to life? • water has an unusually high BP allowing water to exist over a large temperature range • we are made of mostly water

  28. Physical Properties of Water 18. What is another important physical property of water critical to plants? • high surface tension-water sticks to itself very strongly • plants make use of this in order to allow them to draw water from their roots to their leaves

  29. II. Mixtures and Solutions 19. What is a mixture? • two or more substances that are combined but each retain their own properties 20. What is a heterogeneous mixture? • mixture that is not completely uniform throughout, has layers • salt and pepper muddy water oil and water

  30. II. Mixtures and Solutions 21. What is a homogeneous mixture? • mixture that has the same consistency or uniform throughout • salt water air drinking water 22. What is another name for a homogeneous mixture? • solution

  31. II. Mixtures and Solutions 23. What are the two parts of a solution called and what are they? • solute-the stuff that gets dissolved or dispersed(salt in salt water) • solvent-the stuff that does the dissolving or dispersing(water in salt water)

  32. II. Mixtures and Solutions 24. Water mixtures are classified according to the size of the particles dispersed in the water. What are the three classes called and what distinguishes one from the others? • Suspension-very large, easily seen particles. will disperse when mixed but eventually settle out (ex. muddy water)

  33. II. Mixtures and Solutions • Colloid-very tiny particles that cannot be seen that make water look cloudy ex. Milk • Solution-particles are so small and so evenly distributed that they appear to be clear ex. salt water drinking water

  34. Whole milk 1000x

  35. Whole milk 400x

  36. Non Fat milk 400x

  37. II. Mixtures and Solutions 25. How can you tell colloid from a solution? • Called the Tyndall Effect

  38. Molecular View of Water 26. What is water made up of? • atoms of 2 different elements-Oxygen and Hydrogen

  39. Molecular View of Water 27. What is the difference between an element and a compound? • elements are made up of the same type of atom (Copper Iron Oxygen gas) • compounds are made up of two or more different atoms(carbon dioxide CO2 water H2O drinking alcohol C5H7OH, ammonia NH3, Table salt, NaCl)

  40. Molecular View of Water 28. About how many elements are found in nature? • 90 29. About how many compounds are there? • over 8 million 30. What holds atoms in a compound together? • chemical bonds

  41. Molecular View of Water 31. What do we call the smallest unit of a type of compound? • a molecule

  42. Molecular View of Water 32. What are chemical reactions? • involves the breaking and forming of chemical bonds causing atoms to become rearranged into new compounds, usually the new things that form have radically different properties from the compounds that formed it

  43. Molecular View of Water 33. What are chemical properties? • the properties of a substance that describe how it reacts with other substances • oxygen reacts with iron to form rust • hydrogen and oxygen gas will react explosively to form water • sodium metal and chlorine gas will react with great heat to form table salt