APES
 Expect the APES exam to include experimental design
and data analysis questions
 Most common is a controlled experiment
 Don’t forget the control!!!
 Write a testable scientific hypothesis
 Identify the INDEPENDENT and DEPENDENT variables and
predict the relationship
 Isolate one variable to manipulate (independent) and one to measure
(dependent)
 The hypothesis should include a prediction for both variables.
 Again, don’t forget the control group! This is an exact
duplicate of the experiment with no manipulations of
the independent variable
 Collect and analyze data
 Identify the data that must be collected
 Be thoughtful about how to graphically present data
 Common practice to plot dependent on y-axis and
independent on x-axis.
 Draw conclusions
 Use the data to draw conclusions
 Determine if the hypothesis is supported by data
 Do not draw conclusions that are not supported by data
 Publicize the results – science is an open process that
is carried out in public (the findings of scientists are
available for inspection and scrutiny)
 OH, BY THE WAY…DON’T FORGET THE CONTROL!
 It is important to note that chemistry is involved in the
cycling of nutrients, resource use, and pollution.
 Also important to remember that some of the
chemicals in our environment are naturally occurring,
and some, like chlorofluorocarbons, are
anthropogenic, or manmade
 Make sure you know the difference between an
element, compound, atom, isotope, and ion.
 Nomenclature: spending time reviewing this will help
with confusion such as:
 Nitrogen dioxide (NO2), nitrous oxide (N2O),
nitrate(NO3-), nitrite (NO2-), or nitric oxide (NO)
 AP TIP: one way to lose a point in a free-response essay
is by contradicting yourself.
 Example: formula - name
 Carbon
 The backbone of all organic compounds, which includes
all of the important molecules found in living organisms
 Fossil fuel use shifts the equilibrium of the global carbon
cycle
 Carbon dioxide is an
important greenhouse gas
 Nitrogen:
 The most abundant element in the earth’s
atmosphere at 78%
 Found in the amino group of every amino acid, building
blocks of proteins, also components of nucleic acids
 Nitrogen runoff from agricultural land is an important
contributor of nutrient pollution in waterways
 Nitrous oxide (N2O) is an important greenhouse gas
 Oxygen:
 the 2nd most abundant element in the atmosphere at
21%
 Most abundant element in the earth’s crust
 When earth atmosphere was formed, oxygen was not
much of a component, until later…through
photosynthesis by green plants (esp. cyanobacteria)
 It is necessary for cellular respiration
 A component of nucleic acids and phospholipids
 In many ecosystems, it is the limiting factor for
primary production (plant growth)
 P runoff from agricultural land is a major contributor
to nutrient pollution in waterways
 It does not have a significant presence in the earth’s
atomosphere
 A component of some amino acids and proteins
 A major constituent of volcanic eruptions
 A contaminant of coal that contributes to acid rain
 A logarithmic scale covering a range of 0-14 that is
used to differentiate between acidic and basic environ.
 Acidic – below 7, neutral – 7, basic (alkaline) – above 7
 Rainwater naturally has a slightly acidic pH of 5.5-6.0
due to dissolved CO2 from the atmosphere that forms a
dilute solution of carbonic acid (H2CO3) in raindrops
 Radioactive elements decay at a characteristic rate that
is typically measured by the half-life of a sample
 The half-life is the time it takes for ½ of a sample to
decay
 Half-lives vary from a fraction of a second to a billion
years
 Types of energy:
 Mechanical
 Electrical (electromagnetic)
 Nuclear
 Chemical
 Heat (thermal)
 Sound
 Heat
 Different units:
 calories and Btus (British thermal unit)
 1 calorie is defined as the heat required to raise the
temperature of one gram of water one degree Celsius
 1 Btu is defined as the temp. of one pound of water by one
Fahrenheit degree
 1 cal=4.184 Joules (J)
 1Btu=252 cal = 1055 J
 1 000 cal = 1 Cal = 1 kilocalorie
 Power:
 The rate at which energy is used (the rate at which work
is done)
 Unit for power is the watt (which is equivalent to an
energy flow rate of one joule per sec
 1 J/s=1 Watt
 Electrical energy is commonly measured as kilowatthour (kWh)
 The first law of thermodynamics
 Known as the law of conservation of energy
 Energy cannot be created or destroyed, only converted
from one form to another
 The second law of thermodynamics
 Basically states that in all energy conversions, some low-
quality heat (waste heat) must always be produced
 This prevents the reversal of an energy transformation
and the construction of any device with 100% efficiency
 Conversion Factors:
 1 kWh=3400 Btu
 1kWh = 8.6 x 105 calories
 1 cal = 4.184 J
 1barrel = 159 liters = 42 gallons
1. A city that uses 10 billion Btus of energy each
month is using how many kilowatt-hours of
energy?
Conversion Factors:
1 kWh=3400 Btu
1kWh = 8.6 x 105 calories
1 cal = 4.184 J
1barrel = 159 liters = 42 gallons
2. One barrel of crude oil provides about 6 million Btus
of energy.
a. Assuming that all of the energy in the crude oil
could be converted to electricity with 100% efficiency,
how many kilowatt-hours will one liter of crude oil
provide?
b. With the same assumption, how many calories of
energy will one gallon of crude oil provide?
Conversion Factors:
1 kWh=3400 Btu
1kWh = 8.6 x 105 calories
1 cal = 4.184 J
1barrel = 159 liters = 42 gallons
3. If one barrel of crude oil provides 6 million Btus of
energy and releases 150 pounds of CO2 per million
Btus of energy, how much CO2 is produced by each
barrel of crude oil?
 Open system
 Systems that exchange both energy and matter across
their boundaries
 Most environ. systems are open
 Closed system:
 Systems that exchange energy but not matter across
their boundaries
 Example: global water cycle (no matter (water) enters or
leaves the system
 Positive feedback loop
 Negative feedback loop
AP TIP: When determining whether a feedback loop
is positive or negative, focus on the initial and final
states of the system. If the system changes in the same
direction as the input it is a positive feedback loop. If
the system change is in the opposite direction, it is an
negative loop. Don’t get hung up in the details