LAB REPORT OUTLINE
Title:
Date:
(Be sure to label each section of the report)
Purpose
The purpose of any experiment is a concise statement as to why we are performing such an
exercise and what we are trying to prove or learn from it.
EXAMPLE:
The purpose of this experiment is to discover differences between physical and
chemical changes.
Materials
All the materials and apparatus needed to perform the experiment should be listed in column
form. Knowing the concentrations of solutions is vital. You often need this information to
perform calculations and to answer the questions at the end of the experiment.
EXAMPLE:
250 mL beaker
100 mL graduated cylinder
ring stand
hot hands
laboratory burner
6.0 M HCl
Procedure
The procedure used in the experiment should be written in brief, numbered steps. (Paraphrase
the steps in the lab.) You should be able to do the lab based on your procedure. The procedure
should not include instructions on how to do calculations. (Those instructions belong in the
calculation section of the report.)
EXAMPLE:
1.
2.
Find the mass of a 250 mL beaker.
Measure exactly 100 mL of tap water in a graduated cylinder. (etc.)
Observations
Observations are to be brief, descriptive statements. They are to be made at every possible
interval of an experiment. They should be an honest record which does not always reflect the
textbook content or what is reputedly “right". Remember, careful observations will make it
easier for you to recognize chemical reactions.
EXAMPLE:
Reaction
Observation
CaCO3 + 6.0M HCl
rapid bubbling
CaCO3 + 1.0M HCl
bubbling
CaCO3 + 0.1M HCl
slight bubbling
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Data and Calculations Tables
Data may be most efficiently arranged in a form of a table or tables. The columns of the table
must be properly categorized and labeled. Always be sure to place labels on numerical values,
such as 10.00 grams instead of 10. Make sure that all numerical values contain the correct
number of significant figures.
EXAMPLE:
Sample
Glass Rod
Determining Density
Original
Final Water
Mass (g)
Water Level
Level (mL)
(mL)
10.00
50.00
51.00
Volume of
Solid* (cm3)
1.00
1st irregular solid
15.00
50.00
60.00
10.00
2nd irregular solid
20.00
50.00
55.00
5.00
Regular metal
object
25.00
50.00
80.00
30.00
*Calculation for the volume of the solid should be shown in the calculation section.
Graphs
In chemistry, data is often displayed o x-y graphs. There are many components that are
important to a complete graph. They are listed below.
•
Title - brief description of the information that the graph represents, often given in the
form y versus x.
•
Axis Labels – identification of the variable represented by each axis and the unit. The xaxis represents the independent variable. The y-axis represents the dependent variable.
•
Numbered Axes – Indication of the magnitude of the measurements must be provided for
each axis. The distance between two marks must always represent the same difference in
numbers. That is, the y-axis markings could represent 5, 10, 15, 20 etc., but they could
not represent 1, 4, 9, 16 etc because the distance markings changes.
•
Data Points
•
Curve or Line of Best Fit – There are two basic ways to determine the curve on a graph:
connect the data points, point-to point, or draw the best approximation of a smooth curve
through the midst of the data points (though not necessarily through each data point).
Sometimes this approximated curve will take form of a straight line; other times it will be
a curve. In chemistry, since the data points often represent experimental measurements,
the approximation method is preferred. If the data point fall along an approximate line,
the “Line of Best Fit” is drawn. If the points approximate a curve, a smooth “Curve of
Best Fit” is drawn.
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EXAMPLE:
Examine the following graph. This graph shows the amount of a sample of the
radioactive isotope carbon-14 remaining after a given time. A “Curve of Best Fits”
has been drawn.
Calculations
All mathematical computations should be recorded in the lab reports no matter how insignificant
and simple they may seem. This is important for future reference to a particular laboratory
experiment.
EXAMPLE: (This example is based on information from the data table.)
1.
2.
Determine the volume of each solid.
Volume of the solid = final water volume – original water volume
a.
Volume of the glass rod = 51.00 mL – 50.00 mL = 1.00 mL = 1.00 cm3
b.
volume of 1st irregular solid = 60.00 – 50.00 mL = 10.00 mL = 10.00 cm3
c.
etc.
Determine the density of each solid.
Density =
mass
volume
a.
Density of the glass rod =
b.
etc.
10.00 g
1.00 cm
3
3
= 10.0 g/cm 3
Questions
Based on the data and calculations, you should be able to develop a plausible explanation for the
phenomena observed during the experiment. Specific questions are asked that require you to
draw on the concepts you have learned. All questions accompanying a lab experiment should be
answered by making complete statements. In making your response make sure you are restating
the question you are answering. It is not necessary to write the question as stated in you lab
manual. Equations should be included anytime they will help to explain a particular situation.
EXAMPLE
WHAT EVIDENCE WAS THERE TO PROVE THAT THERE WAS A CHEMICAL
REACTION BETWEEN CaCO3 and HCl?
There was evidence of a chemical reaction in the experiment involving CaCO3 and
HCl because a gas was produced.
CaCO3 + HCl
→
CaCl2
+
H2O +
CO2
Conclusion
One of the most important aspects of a laboratory report is the conclusion. The purpose of any
lab exercise is to learn about some particular area of science. In drawing a conclusion from such
an experiment you should look again at the purpose for performing this experiment and then
decide whether or not you established the validity of this hypothesis. Did you really accomplish
what you started out to; did you get accurate results; and where was your source of error? What
improvements would you make if you were repeat the lab or do further study? Specific examples
should be cited from the lab in your conclusion. Again the conclusion should be as brief as
possible but yet contain all the necessary correlation between data, observations, and the original
purpose.
EXAMPLE:
The purpose of this experiment was to discover the differences between physical
and chemical changes. Many physical and chemical changes were observed while
completing this laboratory experiment. A physical change is one that involves a
change in state or matter without changing the chemical composition. Ice melting
and water evaporating are physical changes (example from lab). A chemical
change is one in which the atoms are rearranged to form substances that have
chemical formulas that are different from that of the reactants. Chemical changes
may be observed whenever heat is absorbed or given off. They are also evident
when a new phase is produced such as a precipitate or a gas. The reaction of
calcium carbonate and hydrochloric acid was a chemical change because it produced
carbon dioxide gas (example from lab). Sources of error include . . . Improvements
that could be made include . . .
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