chemistry writing question and need a sample draft to help me learn.
please complete a formal lab report for the following lab, I have attached data needed for completion and guidelines to carefully folllow.
CHM 111/112 Formal Lab Reports – A Guideline
This handout provides guidelines for writing a formal, typed laboratory report for CHM 111/112. These guidelines should be similar (but not identical) to guidelines for reports in other Chemistry, Physics, or Natural Science courses.
Be concise. Say as much as is needed, while using as few words as possible (and still obeying common grammatical rules). Lab reports should be thorough but not repetitious.
Write in the third person. Do not use words such as “I”, “we”, “I believe”, “in my opinion”, etc., especially when referring to the experimental procedure or conclusions.
Use correct verb tenses.
The experimental procedure has already been conducted, so use third person, past tense, passive voice.
The Background and Discussion/Conclusion should be third person, present tense.
Take good notes, and write about what really happened, not what was supposed to happen.
Do not copy the lab handout – that is plagiarism! Use your own words to describe the experimental purpose and background, the experimental procedure, your observations, and your results of the experiment. The lab handout is to be used as a guide. If you really understand why you did what you did, your report can be surprisingly concise.
Lab Report Format:
The following describes in detail the content of the sections required in the report. All sections are expected to be typed.
Title Page. Includes title of the experiment, student’s name, name of lab partner(s), date on which the experiment was conducted.
Introduction. The introduction should include two main categories:
The Purpose or Objective of the experiment, expressed clearly in one or two sentences, including the main method used to accomplish the purpose. Do not directly copy the “Objective” section from the handout, since the handout often lists educational objectives in addition to the objectives for the experiment. Students should only include the experimental objectives.
The Background or Theory of the experiment. This can include information from the introduction in the lab handout, and should include any explanations of theories or equations used. Be concise, and include only the background information that a reader would need to know in order to understand the purpose and methods of the experiment. If useful, an example can be used to illustrate the theory.
Materials. A simple listing of the materials and equipment – it should be complete and accurate. Do not include common supplies like disposable gloves, paper towels, weighing boats, balances.
Experimental Procedure. This section includes the process of the experiment as it was done in the laboratory. It may be written out step-by-step in the form of a bulleted list. This section should be written in the passive voice – it should NOT be a set of instructions. Use the experiment handout as a guide, but include just enough information so that others who read the report would be able to duplicate the experiment at a later date. Do not include any experimental results in the Procedure section.
Results. This section should include all results of the experiment, including:
Raw data – Masses, volumes, temperatures, etc., organized into tables or graphs when appropriate. Use the lab handout as a guide in organizing the data.
Calculated results and/or important observations. Calculated results should be clearly displayed in a table; qualitative results that do not fit in a table or graph may be written out in clear, concise sentences. Use the lab handout as a guide to which results need to be reported. If required, averages and/or percent error should be reported here.
Calculations. Usually only one sample calculation needs to be shown for each calculated result. Be sure to use correct significant figures and correct units for all results and calculations. If required, the calculation for average or percent error is shown here. If a graph is part of the lab, include it in this section.
Discussion/Conclusions. This is the section in which the student shows that he or she has a thorough understanding of the concept of the experiment and the significance of the results obtained. The Discussion should be concise, and may focus on some of the following areas (but not all areas):
Did the completed experiment accomplish the purpose as written in the Introduction? Provide one or two sentences that summarize definitive conclusions from the results.
How did actual results compare with expected results (if known)?
An analysis of the experimental or percent error – comment on the magnitude of the error, and suggest specific potential sources of error. Unless you noted an obvious equipment malfunction in your Experimental Procedure section, do not list equipment malfunction or generic “human error” as sources of error.
Give specific suggestions on how methods could be improved to minimize experimental error.
If assigned, any Post-Laboratory questions should be answered/incorporated into this section.
CHM 111-XXX Fall 20XX
Lab 2 – Physical Properties of Pure Substances and Mixtures
Your Partner’s Name
Date that expt was conducted
The purpose of this experiment was to investigate the relationship between the mass percent and density of a series of increasingly concentrated aqueous salt solutions (in Part A); and to determine the density of an unknown pure metal sample using the concept of water displacement (in Part B). The use of density to calculate other physical properties (e.g., thickness) of a metal sample was also investigated in Part C.
The density of an aqueous salt solution (e.g., CaCl2) is known to be directly proportional to the mass percent of solute in solution. Consequently, if a series of mass percent/density data points is obtained experimentally for an aqueous salt solution, then the graphical relationship between the mass percent of solute and density should result in a straight line. By use of this proportionality, the mass percent of solute in an aqueous solution of unknown concentration can be obtained from its density. (Possibly insert example graph here…)
When a non-reactive solid is completely submerged in a liquid solvent, it displaces a volume of liquid that is equal to its own volume. Consequently, if the mass of the dry solid is known, the density of the solid can be determined experimentally, simply by measuring the volume of liquid it displaces, since d = m/V. The density of the solid can then be used to help identify the solid, by comparing its experimental density to published densities of known metals. (Insert example problem here…)
Just list them. Don’t include routine items such as paper towels, weigh boats, analytical balance etc. Focus on the specific items that are unique to the experiment.
(Third person, past tense, passive voice! Use just enough detail that another student could replicate your results.)
Part A – Determination of Densities of Calcium Chloride Solutions
A clean, dry 1.00 mL volumetric flask/stopper assembly was massed to the nearest 0.0001 g
The volumetric flask was rinsed and filled to mark with deionized water of known temperature; the filled flask/stopper was massed to the nearest 0.0001 g, and the density of pure water was determined.
Previously-prepared aqueous calcium chloride solutions of known mass percent (10%, 20%, 25%, 30%, 40%, 50%) were obtained. The 1.00 mL volumetric flask was rinsed and filled to mark with each solution; the filled flask/stopper assembly was massed to the nearest 0.0001 g, and the density of each solution was determined. Clean disposable pipets were used with each new sample, in order to avoid cross contamination of the experimental data or original sample bottles.
You get the idea…
Results – Part A
(Can be very similar to table/presentation in lab handout)
Volume of flask: 1.00 mL Mass of Empty Volumetric flask/stopper: _____________
Code for Unknown Solution: XXX Mass Percent of Unknown Solution: XXX
Sample Density Calculation: You must show the calculation, not just the result. No one trusts your math unless you show it!
Graph on Page XX
Results – Parts B and C
(Can be very similar to table/presentation in lab handout)
% Error Calculation: You must show the calculations!
Foil Thickness Calculation:
This experiment conclusively demonstrates that physical properties of mixtures and pure substances can be used to help identify unknown solution concentrations (as in the case of the aqueous salt solution in Part A), or even to identify an unknown substance (as in the case of the metal in Part B).
Although the exact concentration of the aqueous salt solution in Part A was not known, the graphical relationship between mass percent and density strongly indicates that that the mass percent of the unknown solution is XX% – see graph on page xx. Since the true concentration of the test solution was not known, no error analysis could be performed; however, the R2 value of xx for the linear trend line suggests a high degree of correlation between the observed densities and mass percent values for all solutions.
The results of Part B indicate that the identity of the metal is most likely XXXX. Error analysis reveals a percent error of XX%. The unusually high error was affected by the fact that a small amount of water accidently splashed out of the graduated cylinder during Trial 2. This type of error could be minimized if additional experimental trials were completed and averaged. Additionally, use of a more precise graduated cylinder to determine the volume of displaced water would probably increase the certainty of each volume measurement. (Obviously, this is where you discuss anything specific that went wrong, and its effect upon your results.)
(If any Post-lab Questions are assigned, they are incorporated into the Discussion section)