1B Look at water and its cont

A Look at Water and Its Contaminants : A Look at Water and Its Contaminants


Chemistry Concepts Covered : Chemistry Concepts Covered Physical Properties Diff between evaporation and BP Important Physical Properties of water Density


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


Physical Properties of Water : 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


Physical Properties of Water : 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


Physical Properties of Water : 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


Examples of Physical Properties : Examples of Physical Properties Color


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


Examples of Physical Properties : Examples of Physical Properties taste odor length volume density


Physical Properties of Water : 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


Physical Properties of Water : 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.


Density: other examples : 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


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


Density : 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.


Density : 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)


Density : 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? 22.7 g 2.00 cc 11.4 g/cc


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


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


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


Physical Properties of Water : 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


Physical Properties of Water : 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


Slide25 : Ice is less dense than water


Physical Properties of Water : 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


Physical Properties of Water : 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


Physical Properties of Water : 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


Physical Properties of Water : 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


Physical Properties of Water : 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


Physical Properties of Water : 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


Slide32 : Do Building Skills 2 on Page 24


II. Mixtures and Solutions : 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


II. Mixtures and Solutions : 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


II. Mixtures and Solutions : 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)


II. Mixtures and Solutions : 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)


II. Mixtures and Solutions : 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


Slide38 : Whole milk 1000x


Slide39 : Whole milk 400x


Slide40 : Non Fat milk 400x


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


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


Molecular View of Water : 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)


Molecular View of Water : 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


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


Molecular View of Water : 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


Molecular View of Water : 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


Examples of Chemical Properties : Examples of Chemical Properties How a chemical reacts with another chemical is a chemical property


Slide53 : Examples of Chemical Properties How a chemical reacts with another chemical is a chemical property


Examples of Chemical Properties : Examples of Chemical Properties Reaction with water to produce new substances


Examples of Chemical Properties : Examples of Chemical Properties How a substance reacts in the presence of heat


Chemical vs Physical Changes : Chemical vs Physical Changes all reactions in chemistry are either physical or chemical changes by understanding what kind of change occurred we can better understand the reaction


Chemical vs Physical Changes : Chemical vs Physical Changes Physical changes involved a change in odor, size, color, phase but not a change in what the substance is. Chemical changes always results in the production of a new substance. What the substance once was, it no longer is...


Chemical v Physical Changes? : Chemical v Physical Changes? the components were mixed in the liquid. The chromatography process simply separates the mixture into its individual componets without changing what they are


Chemical Changes : Chemical Changes Chemical changes always results in the production of a new material


Chemical v Physical Changes? : Chemical v Physical Changes? Clearly the components do not react with one another they are dispersed one in another and can be easily separated: Physical Change


Chemical v Physical Changes? : Chemical v Physical Changes? Production of new materials: Chemical Change!


Slide62 : What is produced now has a new mass therefore it has added something from the air to its chemical makeup. A new substance: Chemical Chemical v Physical Changes?


Symbols and Formulas : Symbols and Formulas 34. What are chemical symbols? letter used to represent the elements C = Carbon H= Hydrogen Na=Sodium


Symbols and Formulas : Symbols and Formulas 35. What are chemical formulas? if symbols are the letters of the chemistry alphabet, chemical formulas are the words formulas tells us two things 1. the elements involved in the compound 2. how many atoms of each element are in the compound using a subscript


Examples : Examples CO carbon monoxide C12H22O11 sugar CaCl2 Deicing salt KNO3 gunpowder


Symbols and Formulas : Symbols and Formulas 36. What are chemical equations? the chemical sentences they describe what things are reacting and what they are becoming chemical formulas are used 2H2 + O2 --> 2H2O


Symbols and Formulas : Symbols and Formulas 37. What do we call what is used up in a reaction? reactants 38. What do we call what is produced in a reaction? products


Symbols and Formulas : Symbols and Formulas 39. What is the molecular structure? it describes not only what a compound is made of but what it looks like as well


Water : Water


Slide72 : 40. What are the diatomic molecules? Elements that exist in nature as couplets, never as single atoms There are 7 of them Just remember Br HONClIF


Electrical Nature of Matter : Electrical Nature of Matter 41. What are some examples of the electrical nature of matter? static cling shocking yourself on a door knob 42. Summarize the electrical properties: positive particles(protons) are attracted to negative particles(electrons) positive particles repel each other negative particles repel each other


Electrical Nature of Matter : Electrical Nature of Matter 43. How do these properties help explain bonding? bonding occurs when the electrons of one atom becomes attracted to the protons of another and they get stuck together, this glue is called a chemical bond 44. Are all atoms equally attractive to the electrons of other atoms? No some are more attractive than others


Electrical Nature of Matter : Electrical Nature of Matter 45. What are polar molecules? molecules that have an uneven distribution of electron due to: 1. unequal sharing of electrons because one atom is slightly more attractive than the other 2. the shape


Electrical Nature of Matter : Electrical Nature of Matter 46. How is it that water is known as a polar molecule? Oxygen is very attractive, it will attract the electrons of hydrogen to it. Because it does this it is kind of negative. The Hydrogen part is very positive because it has very little control over its electrons.


Electrical Nature of Matter : Electrical Nature of Matter 47. How do these properties affect water? it gives water ability to stick to each other really strongly water becomes like a little magnet 48. What happens when one really ugly atom and one really pretty atom come in contact with each other? the outer electron of the ugly atom will take off and be absorbed the pretty one


Electrical Nature of Matter : Electrical Nature of Matter 49. What are ions? what atoms are called when they lose or gain electrons 50. What are the two types of ions? positive ions or cation-the atoms that loses the negative electron negative ions or anion-the atom that gains an extra electron


Electrical Nature of Matter : Electrical Nature of Matter 51. What are the ions that make up NaCl? one Na+ ion and one Cl- ion


Slide86 : 52. What does it mean to be a +1 ion? Give an example. You have lost 1 e- so you have one more positive than negative 53. What does it mean to be a -1 ion? Give an example. You have gained 1 e- so you have more negative than positive


Slide87 : 54. What does it mean to be a +2 ion? Give an example. What does it mean to be a -2 ion? Give an example. You have lost 2 e- so now you have 2 more positives than negatives. You have gained 2 e- so now you have 2 more negatives than positives


Slide88 : 55. What is the most important rule to remember when dealing with ions? You do not gain protons(positives) you only gain e-(negatives)


Ions and Ionic Compounds : Ions and Ionic Compounds 56. How are ionic compounds named? the first name comes from the positive ion the second name is the altered name of the negative ion -ide is added as the new ending 57. What is the name for the following a. NaCl b. MgCl2 c. LiS d. Al2O3


Ions and Ionic Compounds : Ions and Ionic Compounds 58. How do you write chemical formulas? 1. Place the positive ion symbol first with correct charge(check PT for that) 2. Place the negative ion symbol second with the correct charge(check PT for that) 3. If you see a Roman Numeral-that tells you what the charge HAS to be, ignore what the PT tells you 4. Use criss cross method


Ions and Ionic Compounds : Ions and Ionic Compounds 59. Write the chemical formulas for the following: a. Barium oxide b. Potassium fluoride c. Aluminum oxide d. Strontium chloride 60. What are Polyatomic Ions? groups of atoms that together form an ion


Ions and Ionic Compounds : Ions and Ionic Compounds 61. How do you write chemical formulas with polyatomic ions? the same as regular formulas except that you place parenthesis around the entire polyatomic ion when you have more than one of them 62. Where do you find polyatomic ions and their charges? on your ChemOut


Ions and Ionic Compounds : Ions and Ionic Compounds 63. Write the chemical formulas for the following: a. Barium sulfate b. Magnesium hydroxide c. Aluminum sulfite d. Sodium peroxide 64. How do you write chemical names involving polyatomic ions? DO NOT CHANGE THE NAME TO -IDE ending, just write the PI name as is


Dissolving Ionic Compounds : Dissolving Ionic Compounds 65. What is a good way of picturing what dissolving is like? like a tug of war 66. What causes an ionic solid substance to dissolve? if the forces that attract the ions to water is stronger than the force that attracts the ions to each other


Dissolving Ionic Compounds : Dissolving Ionic Compounds 67. Why is water an exceptional dissolver of ionic solids? water is a VERY polar substance, its oxygen part is very negative while its hydrogen parts are very positive 68. Illustrate how water dissolves NaCl


Pure and Impure Water : Pure and Impure Water 69. Does any community in the world receive pure water from their treatment plant? No 70. Why is it useless to insist on pure water? the cost of purifying would be too high it would still be impossible because as long as it is in contact with the atmosphere, gases such as oxygen, nitrogen, and carbon dioxide will dissolve in it


Pure and Impure Water : Pure and Impure Water 71. Why would it be best to not purify water? some gases and minerals give water a pleasing taste some dissolved substances are good for humans small amounts of chlorine containing compounds kills bacteria


Pure and Impure Water : Pure and Impure Water 72. What are some harmful substances that can be found in water and what do they do? High concentrations of Iron: bad taste and deposits on pipes and fixtures Sulfur: bad odor Mercury(Hg), Lead(Pb), Cadmium(Cd) and Arsenic(As) can dissolve and be deadly even in low concentrations


Pure and Impure Water : Pure and Impure Water 73. What are some other sources of harmful water contaminants? pesticides and commercial and industrial waste products


Lab 2 Water Testing : Lab 2 Water Testing 1. How do chemist know when a certain impurity exists in water? They perform confirming test to prove that it is there or not 2. What is a typical confirming test? A chemist will add a chemical to water that will only react with the impurity and with nothing else. It will then form a precipitate


Slide102 : 3. What is a precipitate? A solid that is formed when a positive and negative ion meet for the first time and fall in love, usually associated with a color change 4. These tests are called qualitative, why? We are only concerned with figuring out what it is not how much we have(quantitative)


Slide103 : 5. What four ion impurities will we be testing ORHS water for? Iron III(Fe+3), Calcium(Ca+2), Chloride(Cl-), and Sulfate(SO4-2) 6. Why is it important to call Iron, Iron III? Iron comes in two forms, Fe+2 and Fe+3


Slide104 : 7. You are going to perform the confirming tests on four different water samples? Why three? Which are they? A. Reference: this solution will have the ion in question, it helps you to know what to look for B. Control: Pure water, will not have it C. ORHS water: maybe,maybe not D. Creek water


Slide105 : 8. Would you expect the ion to be present in large amounts in the ORHS water? No it should be in small amounts. 9. Should there be a difference between the Reference and a positive ORHS test? Yes, the ORHS test should be fainter


Slide106 : 10. When you perform the test, why should you use the toothpick that will be provided? To thoroughly mix the two chemicals 11. Should you use the toothpick on the next test? No it would contaminate the next sample, clean the toothpick


Slide107 : 12. You will be using a 24 well plate, what is it? A plastic tray for holding small amounts of chemicals, take a look


Slide108 : 13. Since we will be using these trays and the color change may be faint, how can we make it easier to see the color change? Hold a white sheet paper under the plate Use the table top if you expecting to see a white precipitate


Slide110 : Do Making Decisions on Page 39 in you Chem Groups


Slide111 : One of the most important jobs of a scientists is knowing what questions to ask It helps focus your thinking Large problems can be focused into smaller problems that can be solved To solve the mystery, we need to eliminate some possibilities and zero in on promising ones


Slide112 : Scientists try to disprove all but one of the possibilities in order to conclude what is the answer Remember that there had been a similar fish kill in the Snake River, its cause was water related Next Chapter, we will look a several kinds of water soluble substances and how they could have affected the fish