Experimental Design and Chemistry

1
Experimental Design and Chemistry

• Kady

2
Experimental Design Diagram
The purpose of an experimental design diagram is
to plan an experiment. The table below is the
format for an experimental design diagram.
3
Scenario of Experimental Design
Shawn observed that different kinds and amounts
of fossils were present in a cliff behind his
house. He wondered if changes in fossil content
occurred from the top to the bottom of the bank.
He marked the bank at four positions 5, 10, 15,
and 20 meters from the surface. He removed 5
buckets of soil from each of the positions and
determined the kind and number of fossils in
each sample.
4
Finding the Independent Variable
The independent variable (also known as the
manipulated variable) is the factor in an
experiment that is purposely changed. When
working with an experimental design diagram, it
is best to find the variables first. Once you
find the variables, it is simple to write out
your title and hypothesis. In the scenario, the
independent variable would be meters from the
surface. This was purposely changed so
that Shawn could test to see whether or not there
were different kinds and amounts of fossils in a
cliff behind his house.
5
Finding the Dependent Variable
The dependent variable (also known as the
responding variable) is a factor in an experiment
that is wanting to be observed. This variable
will change in response to the independent
variable. In the scenario, the dependent variable
is the different kinds and amounts of fossils.
6
Finding a Title
The purpose of a title is to describe what kind
of experiment you are doing. This is the format
for a title The Effect of the Independent
Variable on the Dependent Variable. The
underlined parts are what you fill in based on
your experiment. From reading the scenario, you
can arrive at the title. It would be The Effect
of Meters from the Surface on the Different Kinds
and Amounts of Fossils.
7
Finding a Hypothesis
A hypothesis is a proposed scientific explanation
for a set of observations. A hypothesis is
written in the if-then format. The if part is
the independent variable, and the then part is
the dependent variable. A possible hypothesis for
this scenario could be If the meters from the
surface is changed, then there will be different
fossils.
8
Finding the Trial Groups
Trial groups are the different trials of the
experiment. In the experimental design diagram,
the different trial groups are listed in the
first row of boxes. Sometimes the trial groups
can be listed as A, B, C, and D, and other times
they can be listed as trials 1, 2, 3, and 4.
However, in this scenario, the different trial
groups are the number of meters from the
surface. On the first trial, it is 5 meters,
the second trial is 10 meters, the third is 15
meters, and the fourth is 20 meters.
9
Finding the Number of Trials
The number of trials show how much, or how many
times, a sample is being tested. This number
will be the same in each box of the second row.
In the scenario, five buckets of soil are being
removed from each of the positions. It is
necessary to do the trials more than once so you
can have a better understanding of your results.
For nonliving things, each trial should be done
5 times. For living things, it should be done 20
times, and for humans, it should be done at least
25 times.
10
Finding Constants
A constant is the part of an experiment that is
kept the same. It is best to have as many
constants as possible because that will reduce
the number of sources of error you have. In this
scenario, Shawn removed the samples from the
same cliff. Another constant was that five
buckets of soil were removed from each of the
positions.
11
Graphing
If I would make a graph of this scenario, I would
use a bar graph. Since there isnt a way to show
the different kinds of fossils in a bar graph, I
would just be displaying the number of fossils
removed from each trial. The title of my
graph would be The Effect of the Meters from the
Surface on the Amounts of Fossils. The x-axis
(horizontal) would be titled Meters from the
Surface. The numbers would be 5, 10, 15, and
20. The y-axis (vertical) would be titled Number
of Fossils. They would be in increments based
on how many fossils are removed. The x-axis is
known as the independent variable, and the y-axis
is known as the dependent variable.
12
Where Chemistry is Found

• You would find chemistry in fireworks on the 4th
  of July.
• Chemistry is found in the process of cooking.
• Cosmetics, such as makeup and hair products, use
  chemistry.
• You can also find chemistry in artistic things,
  such as lighting, lead, painting, or
• the firing process in sculpting.
• There is chemistry in music-like the sound waves,
  vibrations, and the type of
• instruments.
• The oils in a vehicle involve chemistry.

13
Subatomic Particles and Ions

• protons-positive charge
• located in the nucleus
• electrons-negative charge
• located outside of the nucleus
• There are valence electrons.
  They form bonds.
• neutrons-neutral charge
• located in the nucleus
• ions-atoms with varying number of electrons. Two
  types of ions are cations
• and anions. Cations are metals, and they
  have a positive charge. They
• are on the left side of the periodic
  table. Anions are nonmetals, and they
• have a negative charge. They are on the
  right side of the periodic table.

14
Elements and Isotopes
atomic number- number of protons and number of
electrons
Mass number-how heavy the atom is.
It equals protons neutrons.
element symbol
element name
To find the number of neutrons, take the mass
number minus the atomic number. Sometimes, atoms
of an element can have different numbers of
neutrons. Carbon is this way. It can have 6, 7,
or even 8 neutrons. Atoms of the same element
that have different number of neutrons are called
isotopes.
15
Charges
The row of an element tells you what energy level
it is in. The first column has a charge of 1,
and the second a charge of 2. If you skip the
transition elements and go to the next column,
which will now be the third, you will find it has
a charge of 3. The fourth column has a charge of
4 or 4-. The fifth a charge of 3-, the sixth a
charge of 2-, and the seventh a charge of 1-. The
last column, called the noble gases, have no
charge. They are stable.
16
Writing an Ionic Compound
An ionic compound is the combination of a metal
and a nonmetal. To write an ionic compound, you
use the crisscross method. The first step is to
write the two element symbols with the cation
listed first. For example, if you were wanting
to write the ionic compound of nitrogen and
beryllium, then you would write Be N. The second
step is to write the elements charges. Beryllium
has a charge of 2, and nitrogen has a charge of
3-, so you would write Be2 N3-. When the charges
are written like that, they are called
superscripts. The next step is to crisscross the
numbers. When you crisscross the numbers, the
charges dont matter. Beryllium would have a
subscript of 3, and nitrogen would have a
subscript of 2. The fourth step is to just write
the compound Be3 N2. The subscripts are the
number of atoms. For every 3 beryllium atoms,
there are 2 nitrogen atoms.
17
Carbohydrates
A carbohydrate is one of the main organic
compounds. Carbohydrates are made up of carbon,
hydrogen, and oxygen. Carbohydrates give you
energy. Foods that have carbohydrates include
bread, pasta, and potatoes. There are three types
of carbohydrates monosaccharide (single sugar
molecules), disaccharide (two sugar molecules),
and polysaccharide (three or more sugar
molecules). An example of a monosaccharide is
glucose. Glucose is used in the process of
cellular respiration. The formula for cellular
respiration is glucose oxygen CO2
H2O. To see if something is a
monosaccharide, you use Benedicts solution. Your
sample will turn from blue to a rusty brown
color if it is heated. You do not have to use an
indicator to see if something is a disaccharide.
To test a polysaccharide, your indicator would be
iodine. The color of your sample should turn from
amber to dark purple.
18
Proteins
Proteins are macromolecules that contain
nitrogen, carbon, hydrogen, and oxygen. Some
foods that have protein in them are meat, eggs,
fish, poultry foods, dairy foods, nuts, and
beans. Proteins help to carry out chemical
reactions, transport small molecules in and out
of cells, and fight diseases. They also are used
to form bones and muscles. The building blocks of
proteins are amino acids. Amino acids are
compounds with an amino group (-NH2) and a
carboxyl group (-COOH). There are over 20
different amino acids found in nature.
19
Lipids
Lipids are used to store energy. They are made
mostly from carbon and hydrogen atoms. The common
categories of lipids are fats, oils, and waxes.
Lipids are formed when a glycerol molecule
combines with compounds called fatty acids. If
each carbon atom in a lipids fatty acid chains
is joined to another carbon atom by a single
bond, then it is saturated. If something is
saturated, then the fatty acids contain the
maximum possible number of hydrogen atoms. If
there is at least one carbon-carbon double bond
in a fatty acid, the fatty acid is unsaturated.
Lipids are considered to be polyunsaturated if
their fatty acids contain more than one
double bond.
20
Nucleic Acids
Nucleic acids are macromolecules containing
hydrogen, oxygen, nitrogen, carbon, and
phosphorus. Nucleic acids store and transmit
hereditary information. The two types of nucleic
acids are ribonucleic acid (RNA) and
deoxyribonucleic acid (DNA). RNA contains the
sugar ribose and DNA contains the sugar
deoxyribose.
21
Cholesterol, Fats, and Fish
There are two different types of cholesterol
low-density lipoprotein (LDL), and high- density
lipoprotein (HDL). Bad cholesterol, LDL, should
be less than 130. Good cholesterol, HDL, should
be above 40. Some types of fats are good for you,
but then again, others are not. Saturated fats
can raise your LDL level. That type of fat is
found in meat, dairy, and eggs. Trans fats can
raise LDL levels and also lower HDL levels. Foods
like cookies, cakes, fries, and donuts have trans
fats. The unsaturated fats- monounsaturated and
polyunsaturated-can be good for you.
Monounsaturated fats can lower LDL levels and
raise HDL levels. This type of fat is found in
certain types of oils, nuts, olives, and
avocados. Polyunsaturated fats can lower LDL
levels, but if you have too much of this fat, it
can also lower HDL levels. These are found in
safflower, corn, and sesame. The omega 3
essential fatty acids found in fish have good
health benefits. They help reduce inflammation,
decrease the likelihood of developing
cardiovascular disease, help to control
cholesterol levels, help people with depression
and anxiety disorders, help infants brains and
eyes to develop and function properly, and help
to heal dry skin. Fish can be bad for us, though,
because most bodies of water are polluted with
mercury, so almost all fish are at risk of
containing mercury.
22
Lab Safety
When working in the lab, you should always follow
your teachers instructions. If someone gets hurt
while working in the lab, you should immediately
contact your teacher. You should always wear
goggles in the lab for your protection. Glasses
do not count as goggles because glasses do not
have the side protection like the goggles do. Use
common sense when working in the lab.
23
Labs Accomplished this Unit
Microscope lab- We looked at many different
things through a microscope. The first thing we
looked at was a dead bug. Next, we looked at a
newspaper letter e through the microscope. Then
we looked at cotton and pieces of thread. We
were also able to look at pond water through the
microscope. Carbohydrate lab- In this lab, we
were testing known carbohydrates and
unknown carbohydrates. There were three different
carbohydrate types monosaccharide,
disaccharide, and polysaccharide. We observed
their color change after heating them with
Benedicts solution, and then we observed their
color change after adding iodine. Protein lab-
In this lab, we were given samples, and we were
to figure out if they were proteins. We added
five drops of nitric acid to each sample. If the
sample changed to yellow, then that meant it was
a protein.
24
Microscopes
There are two different types of microscopes that
we used during this unit dissection microscopes
and light microscopes. We used dissection
microscopes to look at solid objects, and we
used light microscopes to look at transparent
objects. Light microscopes produce magnified
images by focusing visible light rays.
Microscopes should always be carried in an
upright position with both hands. You should
always let light microscopes cool a couple of
minutes before you touch it because they can get
very hot. An object should always be located
first with low power. The fine wheel adjustment
must be used to sharpen focus when using high
power magnification. You should always look to
the side of a light microscope when lowering the
objective. Total magnification is determined by
multiplying the eyepiece lens magnification and
the objective lens magnification.
25
Compound Light Microscope
eye piece
coarse wheel adjustment
revolving nose piece
fine wheel adjustment
low power objectives
arm
high power objectives
stage
stage opening
stage clips
base
diaphragm
light source
26
Functions of a Microscope
diaphragm-regulates amount of light entering
scope stage opening-allows light to pass through
stage mirror or lamp-directs light into
scope eyepiece-contains a lens capable of 10X
magnification low power objective-attached to
revolving nosepiece and contains a lens
capable of 10X magnification high power
objective-contains a lens capable of 43X
magnification revolving nosepiece-turns to change
from one power to another coarse wheel
adjustment-brings objects into rapid but coarse
focus fine wheel adjustment-brings objects slowly
into fine focus stage-supports slide stage
clips-holds glass slide and specimen in place