AP Chemistry Lab Write-Up
1.
Name
Class
Title of Experiment
Date Lab Performed
Date of Report
Lab Partners: Names of lab partners
Teacher: Mrs. Hintz
2.
Purpose: What are the main reasons you are performing this experiment. Be
specific and include your hypothesis. Do not restate the title or copy the
experiment objectives.
4.
Chemical Reaction: Write out any chemical reactions that are occurring in the
experiment in the form of a balanced chemical equation.
5.
Chemical Properties Table: This table is for any chemical used during the
experiment. ChemPub is a good resource for these properties. Include molecular
weight, melting point, boiling point, density, toxicity, color, solubility
Name
Benzaldehyde
MW
MP
106.1 -26 C
3
g/mol
Acetone
BP
178 C
Density
1.04
g/cm3
Toxic
Irritant
58.08 -95 to - 56 C
g/mol 93 C
0.790
g/cm3
Sodium Hydroxide
39.99 318 C
71
g/mol
2.13
g/cm3
Dibenzalacetone
234.3 60
C 130 C
0
cis/tran cis/tran
g/mol s
s
Flamm
able
NonToxic
Chemic
al
burns
and
Blindne
ss
Irritant
1388 C
Color
Colorles
s Liquid
(almond
odor)
Colorles
s Liquid
Solubility
.6 g/100 mL
20 C
White,
waxy,
opaque
crystals
1110 g/L 20
C
Yellow
Solid
Insoluble in
water
Miscible
water
in
6. Materials: List equipment and amounts of listed substances used.
7. Procedure: Written as a sequence in past tense
1.) 2 mL of 3 M sodium hydroxide solution were placed into a 10 X 100 mm reaction
tube.
2.) 1.6 mL of 95% ethanol and 0.212 g of benzaldehyde were added to the solution.
3.) 0.058 g of acetone were added to the reaction mixture.
4.) The tube was capped and shaken immediately for approximately one minute until a
yellow precipitate of the product formed and the solution became cloudy.
5.) For the next thirty minutes the solution was shaken intermittently.
6.) The inside of the tube was scratched to encourage crystallization.
7.) The liquid was removed from the tube using a Pasteur pipette, and the crystals were
left behind.
8.) 3 mL of water were added to the tube, capped, and shaken vigorously.
9.) The liquid was removed from the tube using a Pasteur pipette.
10.) The crystals were washed two more times with 3 mL of water.
11.) The crystals were collected in a Hirsch funnel using vacuum filtration.
12.) The crystals were placed in-between two pieces of filter paper to dry.
13.) The crude dibenzalacetone was recrystallized using a 70:30 ethanol-water mixture.
14.) During recrystallization a wooden boiling stick was inserted into the reaction tube.
15.) The tube was allowed to cool to room temperature in an insulated container on ice
for several minutes.
16.) The solvent was removed using a Pasteur pipette.
17.) The mixture was washed with 0.5 mL of ice cold 70% ethanol while it stayed on
ice.
18.) The melting point was determined.
8. Data: Tables and graphs with all labels, and any calculations utilized in the
experiment
9. Data Analysis:
Present the data collected and discuss how the data was obtained.
Discuss how the data obtained and explain any calculations – do not restate the
procedure
Analyze why the data is relevant
This section of the lab should contain only statements you can support with your data,
NOT your opinions. Every statement should be backed up by quoting your data and/or
referencing by title, relevant tables, charts or graphs within your report. For example, in
your “data” section you recorded the freezing point of unknown sample #1 to be -5oC. In
the “data analysis” section you will further analyze that data: "We used an electronic
temperature probe and determined the freezing point of sample #1 to be -5oC as noted
in Figure 2 by the flat portion of the curve. This shows that the addition of a solute
(NaCl) lowered the freezing point by 5oC when compared to the curve of the pure
sample shown in Figure 1."
10. Conclusion:
A brief paragraph where you:
*restate your hypothesis/objective
*quote data that proves you met or did not meet the objective
*describe possible sources of error and how they affected your data
*suggest how to improve your results if you were to repeat the experiment
* use this section to analyze sources of error and how those errors influenced
the data