The symbols in chemistry get in the way of getting to know elements and compounds.

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Practice Test for CHM151 final exam part 2.

• The symbols in chemistry get in the way of
  getting to know elements and compounds.
• H2O is water, true or false? (false)
• The formula for water is H2O, true or false?
  (true)
• What is the color of Au? (black)
• What is the color of the element represented by
  Au? (gold or yellow)
• Symbols make elements all look alike. For
  example (F, Cl, Br, and I) seem like the same
  size. However, which is the smallest? (fluorine)
  The largest? (I)
• Ca and Ca2 seem like the same size, however,
  draw them to show their relative sizes.
• O and O2- seem like the same size, however, draw
  them to show their relative sizes
• CO2 appears to have carbon on the left side and 2
  oxygen atoms on the right side. Draw CO2 using
  spheres for carbon and oxygen. Label them.
• Draw the VSEPR structure of H2O.
• Chemistry uses the same symbol for many different
  things.
• In 3 Liters 2 Liters, what does the mean?
  (It means to combine the quantities
  mathematically.)
• In 2Ag Cl2 ? 2AgCl, what does the mean? (It
  means the two are mixed but not necessary
  combined.)
• In Ag(aq) Cl- ? AgCl(s), what does the
  mean by the Ag? (It means Ag has lost an electron
  giving it a positive 1 charge)
• If the heat of a reaction ?Hrxn 91kJ, what
  does the mean? (It means the products of the
  reaction has gained 91 kilojoules of energy. It
  is an endothermic reaction.)

Ca
Ca2
O2-
O
2

• DIMENSIONAL ANALYSIS. Where math classes relied
  more on solving an equation, chemistry will
  usually do dimensional analysis. For example, the
  equation for distance is dvt (velocity x time).
  So this says multiply velocity times time and you
  get distance. In chemistry, you dont think much
  about the equation but look at the units. If you
  see miles per hour and you see hours, you set it
  up to to get the final units to be a distance.
• In math, to find t (time), you may solve the
  equation with algebra to show that td/v. So
  you divide the distance by the speed. In
  chemistry, you look at the units. When given a
  distance of 700 meters per second and a distance
  of 2100 meters, you look at the dimensions to
  tell you how to solve for time. .
• If the speed was in meters per second but
  distance was 6 miles, you would do more
  conversions to get the answer to have the right
  unit. You dont depend on a formula. You let
  the dimensions tell you what to do. Dimensional
  analysis is a series of multiplication problems
  that often involves multiplying by a rate (e.g.,
  1.6km per mile).
• Some problems are best done with a combination of
  algebra and dimensional analysis.

55 miles 4 hours 220 miles
hour
1 sec 2100 meters 3 seconds
700 meters
1 sec 6 miles 1600 meters 13.7 seconds
700 meters 1 mile
Concentration x Volume Concentration x
Volume
2 drops of a 4 bleach solution is diluted to 1
quart. What is its new concentration in ppm
(mg/Liter)?
4 g 2 drops ? mg quart
100 mL Liter
4 g 2 drops Liter ?
100 mL mg quart
Multiply and divide both sides by the units on
the unknown side to isolate unknown (?) value
Look to see what units cancel. If all dont
cancel, add conversion units to cancel all units.
Our answer is 2.8. If we wrote the original
unknown concentration as mg/Liter that means the
answer is 2.8 mg/Liter, which is 2.8 ppm.
4 g 2 drops Liter 1 mL milli 1.057 quarts ?
100 mL mg quart 30 drops 0.001 1 Liter
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• MAKE IT REAL. Because chemistry relies heavily
  on symbols, it is easy to forget what is
  represented. When you come across a formula or
  name for a substance, do a search for images of
  that substance.
• Know your Internet resources
• Google (or something similar) for finding Web
  articles.
• Google (or something similar) for finding images.
• www.wikipedia.com for encyclopedic articles.
• www.dictionary.com for definitions and
  pronunciations.
• www.webelements.com for information on elements.
• http//www.chemistrycoach.com/tutorial.htm for
  links to many tutorials.
• http//www.chemtutor.com/ for tutorials.
• www.chemistryland.com your instructors website
  with many PowerPoint presentations.
• Another way to teach yourself about compounds is
  to build models of them or use chemistry modeling
  software. One site that has free computer
  modeling software is www.acdlabs.com.
• BE SKEPTICAL. It doesnt help to learn a lot of
  chemistry and then let yourself get duped by
  bogus products or stories. To gain awareness of
  past and present myths and urban legends, visit
  these sites.
• www.snopes.com
• http//hoaxbusters.ciac.org/
• www.greenfacts.org
• Be more skeptical of information you find. If the
  site uses the following tactics, be skeptical
• 1. The use of technobabble (technical
  descriptions that are meaningless and have no
  basis in real science)
• 2. Fantastic claims (When things sound too good
  to be true, then they probably aren't true.
  Fantastic health claims are the most common.)
• 3. Something is being sold (when money is at
  stake, there is more incentive to be deceptive)

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• GET INSPIRED
• Chemistry (and science in general) is really
  amazing. You should always look for ways to be
  inspired and to round out your knowledge of
  current developments.
• Get subscription to science magazines or visit
  their websites
• Discover
• Popular Science
• Popular Mechanics
• Scientific American
• New Scientist
• Watch DVDs or television programs about science
• Discovery channel Mythbusters, Alien Planet, I
  Shouldnt be Alive, etc.
• Nova series The Elegant Universe, World in
  Balance, The Miracle of Life, The Best Mind since
  Einstein
• The Learning Channel Honey Were Killing the
  Kids.
• Visit Science Museums, attend conferences, attend
  presentations and other events.
• Arizona Science Center
• American Chemical Society
• Presenters at ASU, MCC, or elsewhere in the
  valley.
• Star gazing events.
• Job Shadowing
• Find someone who is in the career that you are
  aiming for and spend time with them.

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CHM151final exam part 2 contd. Instructor Ken
Costello
Topics
Visuals
Building Blocks
Forces Energy
Mathematics
Freezing point depression is a achieved by an
antifreeze like ethylene glycol, but anything
that dissolves in water will act as an antifreeze.
Normally, knowing what building blocks are
present is important, but for colligative
properties, the only thing that matters is
what? Quantity
When salt is added to ice, it creates a mixture
that is more random (has more entropy). This
form of energy gets its energy from its
surroundings by making it cold. How cold can a
mixture of salt ice get? Zero degrees Fahrenheit

• The freezing point depression constant for water
  is -1.86C/m. If 292 g (5 moles) of NaCl is added
  to 3 L of water, what is new freezing pt?
• A. 6.2C
• B. 3.1C
• C. 9.3C

A
The mineral in teeth is apatite with formula
Ca?(PO4)3OHHow many Calciums are needed to make
this compound neutral? Five
Prescription fluoride toothpaste is 0.4 wt/vol
fluoride. How many grams of fluoride in 1 liter
(about 10 tubes)? 4 grams. Will it kill you if
lethal dose is 5 grams? No.
Fluoride (F-) in high doses is lethal, in low
doses it is used to fight tooth decay.
Acids attack the OH in apatite turning the OH to
H2O. The apatite is left with 1 charge. How
will water respond? Negative end of water will
be attracted and pull apatite apart
Copper metal dipped in a solution of silver
nitrate will dissolve. The dissolved silver
becomes metallic silver. What kind of reaction is
this?
Write NR next to the ones that have no
reaction Fe(s) Ag(aq) ?Ag(s) Al3(aq) ?
NR Au3(aq) Ca(s)?Cu(s) Mg2(aq)?NR
If 127 grams of copper wire dissolved in
AgNO3(aq) to make copper (I) nitrate, how many
grams of silver precipitated out?
In chemical reactions elements rearrange
themselves.
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Building Blocks
Forces Energy
Mathematics
Topic
Visuals
Looking at the atomic weights, what element needs
to fuse with oxygen to make silicon? Carbon.
Millions of degrees are needed for elements to
fuse together. Why? To overcome electron to
electron proton to proton repulsions

• The remains of a supernova are neutrons at
  density of 454 billion g/cm3. A teaspoon (5 cc)
  of this weighs how many lbs.?
• A. 17 battleships (5 billion lbs)
• B. 9 locomotives (1 million lbs)
• C. 454 billion lbs.
• D. 1 million grams.

Supernovas are responsible for creating the 100
elements we know of.
A
The Periodic Table of the Elements organizes
elements in rows and columns.
If sodium had been the building block, find an
alternative with similar properties. One of
these Potassium (K), Lithium (Li), Rubidium
(Rb), or any from Group 1A.
Which column in the Periodic Table has elements
that pull the hardest on electrons? 7A Or 17
Electronegativity measures attraction to
electrons F4.0, Na0.93, K0.82, Cl3.16. Which
has stronger bond, NaF or KCl? NaF
These seven non-metals combine to make poisonous
gases. Knowing which gases are lighter or
heavier than air could save your life.
Name this compound P3O5 (2pts) Triphosphorus
pentaoxide
Air inside a hot air balloon is a mixture of
nitrogen, oxygen, carbon dioxide, water vapor,
and carbon monoxide. What force is causing the
hot air balloon to rise? Gravity.
To compare densities of gases, compare molecular
weight. Which is more dense, nitrogen monoxide
or carbon monoxide? Nitrogen monoxide.
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Topic
Visuals
Building Blocks
Forces Energy
Mathematics
Groups 1A, 2A are called alkali metals alkali
Earth metals. The name alkali is Arabic for
the saltwort plant.
The ashes of the Al Kali plant contain hydroxides
(OH-) of groups 1A 1B. These neutralize acids
(H) to make what? Water
Lab students are warned about adding acids (H)
to bases (OH-). These neutralize each other, so
whats the problem? A lot of heat is
produced. (optional) It may boil and splash.
Two moles of Ca(OH)2 is mixed with 3 moles of
H2SO4. How many moles of water is produced? 4
moles
Water absorbs heat well, which is why its used
in car radiators.
Draw a water molecule. Label atoms and show where
partial charges are..
What causes water to have a higher than expected
boiling point? The - ends of water pull on
each other.

• How many calories is needed to raise 53 gallons
  (200 Liters) of water in a water heater from 20C
  (room temp) to 70C?
• A. 10,000 calories
• B. 100,000 calories
• C. 10,000,000 calories

H
H
O
C
What are those 6 elements? 6pts Hydrogen Carbon Ox
ygen Nitrogen Sulfur Phosphorus
In living things, energy from sugar makes ATP
(adenosine triphosphate) which provides energy
for reactions. How many phosphate groups are in
ATP? 3
Energy from ribose comes from this reaction.
Balance it. C5H10O5 O2 ? CO2 H2O C5H10O5
5O2 ? 5CO2 5H2O
Living things are built from 6 elements with a
few metals needed for certain proteins.
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Topic
Visuals
Building Blocks
Forces Energy
Mathematics
Supernova explosions spread elements all over the
universe. Gravity collects elements to form new
stars and solar systems.
Helium is 2nd most abundant element in universe,
yet very little is on Earth. Why? (2pts) Being
light it is lost to space. Being inert, it
doesnt bond.
Would a helium balloon released on surface of
the moon float or sink? Why? (2 pts) It would
fall. Gravity is the reason(optional there is
no air to lift it)
Abundance is given in , ppm, or ppb. Write
these as fractions. (3pts) 1/100, 1/1,000,000 1/1,
000,000,000
Atoms are too small to count, so chemistry
resorts to indirect ways of counting. I call it
the art of counting without counting.
Making trillions of molecules of CO2 is easy
burn coal. Why is making one molecule hard? They
are too small to see or handle.
Gas pressure depends on the speed of the gas
molecules. How does temperature affect the
speed?Speed is proportional to temperature(or
temperature goes up, speed goes up.)
Some syringes can measure 1 µL of gas. How many
atoms of helium are present if pressure is
1.0x10-4 atm and temp is 0C. (R0.0821) 2.7
trillion atoms of helium(2.7 x 1012 atoms of
helium)
Below is the structure of the fungicide he died
from. If someone burned this fungicide, could
hydrogen cyanide HCN and hydrochloric acid
HCl be products of this burning (assume
hydrogen could come from moisture in the
air)? Yes.
The Internet is full of hoaxes and myths. Many
relate to chemistry. Claim A golfer who had a
habit of chewing on his golf tee died after
playing 4 rounds of golf. He died from ingesting
fungicide sprayed on the grass by chewing on the
golf tee. Status TRUE
Hoax Myth Busters.
Carbon nitrogen are bonded in the molecule (CN)
by sharing 3 electrons each. Nitrogen has one
pair of electrons not involved. Which would be
attracted to this pair of electrons, acid H or
base OH-?
A liter of diet soda has 500 mg of aspartame.
1/10 of the aspartame will decompose into
methanol. EPA set daily dose of 0.5 mg per kg
body weight for methanol. I weigh 100 kg. What
is my limit for methanol?50 mg. If I drink 2
liters of diet soda, do I go over that limit? Yes.
H
C N
..


unpaired