Instructions for Brass Analysis Lab Report

This will be an individual lab report. Each group will perform the experiment and collect the data but the actual writing is to be done on an individual basis.

The lab report will require four (4) sections - Introduction (3 points), Results (7 points), Discussion (7 points) and Questions 10 points). An additional 3 points will cover appearance, spelling and grammar. The lab report must be typed in 12 point font and all sections must be in the same font (Calculations should be typed; do not use a caret for exponents). Clearly indicate the sections of the lab report and follow the sequence given above. Use a formal, analytical style of prose. Do not use words like "got", or "thing" and do not use contractions (e.g. it's for it is or don't for do not) Part of your grade will be based upon the satisfactory determination of copper in the sample. .

Introduction:. Provide a paragraph of background information on the history of the use of brass. State a purpose for the experiment. The introduction should be at least 50 words.

Results: This section should contain the following:

A. A table of the class data of the density determination.

B After the density data there should be a section on the calculation of the percent copper and the percent zinc in the brass screws from the density data. (Remember that percent copper plus percent zinc is assumed to equal 100%)

C. A graph of the standard curve for the copper determination as was described in class. The graph should be prepared using Excel (see instructions on website under Handouts, Chapter One) Included in your graph should be a trend line (line of best fit) and the equation for a line.

D. A calculation of the percent copper based upon the absorbance of the unknown and its comparison to the standard curve (use the formula for a line and substitute the unknown absorbance for the y value, then multiply by the total volume to get the total amount of copper in the sample. Then divide by the mass of the brass to get the mass percent of copper in the sample).

Discussion: This section should contain three paragraphs. The first paragraph should be a summary of the experiment. This should be between 75 and 100 words. The next paragraph should discuss your results and your conclusions and reasoning regarding the percent copper in the brass screws. Is the data internally consistent, i.e. do the density and spectrophotmetric data compare favorably? Is the data consistent with published values for the percent copper in brass? This should be between 75 and 100 words. There should be specific reference to results of the different tests. The last paragraph should include a discussion of potential sources of error in your results and suggestions for improvement. This last paragraph is where you should discuss the precision of your measurements in terms of standard deviation. The last paragraph should be about 50 words.

Questions: Answer the questions at the end of the lab handout. A copy of can be obtained online at the website.