Title: A Look at Water and Its Contaminants
1A Look at Water and Its Contaminants
2Chemistry Concepts Covered
- Physical Properties
- Diff between evaporation and BP
- Important Physical Properties of water
- Density
3Chemistry Concepts Covered
- Chemical Properties
- Types of Mixtures
- Chemical Formulas/Symbols
- Electrical Nature of Matter
- Ions
- How to Write Ionic compounds
4Physical 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
5Physical 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(No Transcript)
7(No Transcript)
8Physical Properties of Water
- 3. How much of the earths 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
9Examples of Physical Properties
10Examples of Physical Properties
- Is it a gas, liquid, or solid?
11Examples of Physical Properties
- taste
- odor
- length
- volume
- density
12Physical 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
13Physical 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.
14Density 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
15Density
- Two materials styrofoam and brick. Same
volume. Same mass?
16Density
- 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.
17Density
- Density is defined as the mass of a substance per
the volume of the substance - Mathematical formula D M/V where D Density,
MMass(g), VVolume(mL or L)
18Density
- 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?
19Density
- Ex.2 A piece of lead occupies a volume of 4.00
cc. What is the mass of the lead?
20Density
- 3. A piece of lead has a mass of 302 g. What is
the volume of the lead?
21Density
- Mercury the most dense liquid (13.55 g/cc)
Gold the most dense solid (19.32 g/cc)
22Physical Properties of Water
- 10. Rank the phases of matter in terms of most
dense to least dense - most solids--gt most liquid--gt gas
- 11. What is a good example of an exception to
number 10? - water
23Physical 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
24(No Transcript)
25Ice is less dense than water
26Physical 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
27Physical 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 100C
28Physical 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 0C,
boiling takes place only at around 100C - evaporation only occurs at the surface, boiling
takes place under the surface
29Physical 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
30Physical 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
31Physical 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
32II. 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
33II. 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
34II. 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)
35II. 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)
36II. 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
37Whole milk 1000x
38Whole milk 400x
39Non Fat milk 400x
40II. Mixtures and Solutions
- 25. How can you tell colloid from a solution?
- Called the Tyndall Effect
41(No Transcript)
42(No Transcript)
43(No Transcript)
44Molecular View of Water
- 26. What is water made up of?
- atoms of 2 different elements-Oxygen and Hydrogen
45Molecular 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)
46(No Transcript)
47Molecular 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
48Molecular View of Water
- 31. What do we call the smallest unit of a type
of compound? - a molecule
49Molecular 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
50Molecular 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
51Examples of Chemical Properties
- How a chemical reacts with another chemical is a
chemical property
52Examples of Chemical Properties
How a chemical reacts with another chemical is a
chemical property
53Examples of Chemical Properties
- Reaction with water to produce new substances
54Examples of Chemical Properties
- How a substance reacts in the presence of heat
55Chemical 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
56Chemical 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...
57Chemical Changes
- Chemical changes always results in the production
of a new material
58Chemical 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
59Chemical v Physical Changes?
- Production of new materials Chemical Change!
60Chemical v Physical Changes?
- What is produced now has a new mass therefore it
has added something from the air to its chemical
makeup. A new substance Chemical
61Symbols and Formulas
- 34. What are chemical symbols?
- letter used to represent the elements
- C Carbon H Hydrogen NaSodium
62(No Transcript)
63Symbols 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
64Examples
- CO carbon monoxide
- C12H22O11 sugar
- CaCl2 Deicing salt
- KNO3 gunpowder
65Symbols 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 --gt 2H2O
66Symbols 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
67Symbols 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
68Water
69(No Transcript)
70(No Transcript)
71(No Transcript)
72- 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
73(No Transcript)
74(No Transcript)
75Electrical 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
76Electrical 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
77Electrical 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
78Electrical 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.
79Electrical 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
80(No Transcript)
81Electrical 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
82Electrical Nature of Matter
- 51. What are the ions that make up NaCl?
- one Na ion and one Cl- ion
83(No Transcript)
84(No Transcript)
85(No Transcript)
86- 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
87- 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
88- 55. What is the most important rule to remember
when dealing with ions? - You do not gain protons(positives) you only gain
e-(negatives)
89Ions 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
90Ions 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
91Lab 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
92- 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)
93- 5. What four ion impurities will we be testing
ORHS water for? - Iron III(Fe3), Calcium(Ca2), Chloride(Cl-), and
Sulfate(SO4-2) - 6. Why is it important to call Iron, Iron III?
- Iron comes in two forms, Fe2 and Fe3
94- 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
95- 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
96- 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
97- 12. You will be using a 24 well plate, what is
it? - A plastic tray for holding small amounts of
chemicals, take a look
98- 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
99(No Transcript)
100Ions 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
101Ions 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
102Ions 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
103Dissolving 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
104Dissolving 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
105- Sodium chromate
- Copper II hydroxide
- Iron III chloride
- Barium phosphite
- FeCl3
- NaOH
- Sr(NO3)2
- CuF2
106(No Transcript)
107Pure 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
108Pure 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
109Pure 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
110Pure and Impure Water
- 73. What are some other sources of harmful water
contaminants? - pesticides and commercial and industrial waste
products
111b
- 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
112- 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