Example Lab Write-up
TITLE: Gas Stoichiometry Lab
Name
Period
Date
PURPOSE: (lab notebook & lab report)
The (goal, purpose) of this (experiment, laboratory work, study) is to (experimentally,
empirically) (determine, derive, calculate) the molecular mass of butane, C4H10.
(Empirical: relating to observation or experience)
BACKGROUND: (lab report)
Discuss Dalton’s law, and how, in our experiment, water vapor must be included in the gas
mixture based our collection method. Using the atmospheric pressure as the total pressure, we can
subtract the partial pressure of the water vapor (temperature dependent!) to obtain the partial pressure
of the butane. Include a discussion on how the experimental pressure is used with the Ideal Gas Law to
determine molar mass – be specific.
PRE-LAB ASSIGNMENT: (lab notebook)
Calculate the theoretical molar mass of butane, C4H10.
PROCEDURE: (lab notebook; you have the option to cut & paste these steps into your notebook; include
one drawing.)
PROCEDURAL SUMMARY: (lab report)
Summarize the laboratory procedure in an expository paragraph, (do not write very step!)
SAFETY PRECAUTIONS: (lab notebook)
 Do not inhale the butane gas.
 Wash hands before leaving.
OBSERVATIONS: (lab notebook, lab report)
This section includes your descriptions and experimental data, summarized in a data table. Use
the table provided in your lab handout (cut & paste into the book or recreate.)
ANALYSIS/CALCULATIONS: (lab notebook – raw calculations; lab report – calculations neatly presented
in a data summary table).
Again here, you can use the “Conclusions Data Table” from the handout – cut & paste in your
notebook or recreate. Perform the calculations required (see handout Calculations 1-6). Respond to the
Questions (see handout Questions 1-3). Put draft responses in lab notebook, and final responses in your
lab report.
CONCLUSIONS: (lab report)
The calculated molar mass of butane from our experiment was ________ g/mol. The actual
molar mass of butane, C4H10 is _________. The percent was __________%. Potential sources of
experimental error included ______________________________________.
CONCLUSIONS: (lab report)
SUMMARY: (lab report)
Reiterate the purpose, and discuss your discoveries.