# 1818 ACC Chemistry

Penny Density Lab Report overview 1. Title and heading 2. Introduction: Info on density and using graphing to find density, volume by water displacement, context of pennies 3. Purpose: To determine density of older (before 1982) and newer (after 1983) pennies using graphs. 4. Hypothesis: Which density do you expect to be higher? 5. Procedure: What YOU DID in past tense 6. Data: both mass and volume for some number of pennies. 7. Data Analysis: Graphing Mass vs Volume. 2 graphs. Best fit line slope = density. 8. Discussion: Evaluate results with percent error. State at least two sources of error. Questions.

9. Conclusion: Refer to Purpose and Hypothesis. Data Analysis For completing the calculations table: Make sure you subtract initial volume from volume data and initial mass data from mass data. Verify that you place your volume differences in the X variable column and your mass differences in the Y variable column. Include units of mL for volume and g for mass. Verify that the largest penny mass you recorded occurs for the 7 older pennies. Data Analysis For preparing your graphs 1) Look at calculated data for volume (mL) in each tables. Find the maximum value there.

2) Set an x scale for volume that includes your max value and zero and is each to use: 1 block = 1, 2, 5 or 10. 3) Repeat Steps 1 and 2 for the mass data and put scale on the y axis. 4) Plot points for one table and draw a best fit line. (see image) 5) Repeat Step 4 for the other graph. Label your graphs with new and old in the titles. 6) Finish your graphs with a titles and axis labels Data Analysis Finding density from your graph: Find TWO POINTS ON YOUR BEST FIT LINE that pass through an intersection of graph paper lines. DO NOT USE YOUR DATA POINTS.

Record the coordinates of a point at each end of your line. (x1 , y1) and (x2 , y2) Calculate the density = slope between these two points: https:// www.youtube.com/watch?v=CCe6paXiW oQ A video that summarizes the process of graphing to find density. General Laboratory Report Format Although Labs may be performed in class with a partner and data will be shared each student is responsible for their own lab report. Students who submit a group lab report or lab reports that are almost identical will receive a zero. Typed Lab Reports are preferred, but handwritten are acceptable. Digital reports are insufficient. Perform lab work in pairs

Share data with partner Each student writes their own report Hybrid typed-written is easiest. Attach hand drawn graphs to back of report. Then attach original data table and prelab questions. Check your report with checklist 1. Title (1 pt) Title: Name the report. Something like Chemistry Lab Report is not specific enough. Should say something about

pennies, densities and the two time frames. Include header information near the title (just above or below): Your name, lab partner name, date experiment performed and date report is submitted. DOES NOT NEED TO BE A SEPARATE PAGE. 2. Introduction (3 pts) Introduction (or Background): This should be written in the 3rd person. This should be several sentences to introduce the lab and background information, ideas, formulas, or chemical equations important to the lab. Sometimes you may reorganize class notes into a short paragraph. It is not an abstract and it is not the purpose of the lab. Use a subheading Introduction

What concepts, or formulas should be included for this lab? 1) Density formula and how density can be measured graphically 2) How water displacement to measure volume works 3) History of penny density changes 3. Purpose(s) (2 pts) Purpose/Problem: State what the problem is that you are researching. What are you trying to accomplish or determine in this lab? (may be a statement(s) beginning with To or a question(s)) Use a subheading What is the purpose of this lab?

To measure the density of older pennies from before 1982 To measure the density of newer pennies from after 1983 4. Hypothesis (2 pts) Hypothesis: What is your prediction to the outcome of the lab? Your hypothesis should be should be a clear, and exact description of what should happen and why. It can be more than one sentence. It can be in a logical format like ifthen... format. Use a subheading Predict which density you expect to be higher. Justify your prediction

5. Procedure (3 pts) Procedure (written in 1st person.) Use a subheading A. First list materials, equipment, and size/amounts of everything used. B. List the steps taken in complete sentences, past tense and first person. This part should be written clearly enough that anyone could duplicate your experiment. Do not write what I told you to do but what you did. Include the IV and DV if appropriate. Include how the DV was monitored. Were there controls? How was all relevant data recorded and how many trials did you perform? Describe what YOU ACTUALLY DID!!

Should be similar to printed procedure but written in past tense. Should include the specific kind of balance you used and the specific size graduated cylinder used. 6. Data (3 pts) DataThere may be two types Use a subheading A. Qualitative- This will involve the 5 senses. You may use pictures or diagrams with an explanation of the images. Data Table Organized and Easy to read. Attached raw data table for

accuracy check. Verify that all and only measured quantities are reported in the data table. Remember to include qualitative obs. B. Quantitave This is all the raw numerical data. It should be presented in a labeled table with units of measure and titles and reflect the proper number of significant digits. 7. Data Analysis / Results / Calculations (3 pts) Data Analysis: This is where all the calculations will be correctly calculated and presented. It may be in the form of charts, graphs, tables etc. All graphs and charts should have a title, labels, appropriate data and units. All results should be explained here. What does the data mean? Are there patterns in the

data? Identify this and describe it. If the lab has questions with it, they should be answered here. Use a subheading Calculate your mass and volume data sets Graph your two (x,y) data sets Draw best fit lines Determine the slopes of your lines Pick two points ON A LINE (NOT DATA POINTS) Use the slope formula (y2-y1)/(x2-x1) to find the slope between these two points

Attach hand drawn graphs to lab report. 8. Discussion (3 pts) Discussion:(1st person): In paragraph form, discuss your results. Evaluate the lab and your results. How do your results compare to the accepted or known value or findings? Did you think of further questions after completing this lab? What were the strengths and weaknesses in the set up and methods used? How would you improve the lab? Identify and critique procedural mistakes or sources of error (at least 2) that could affect the data. Use a subheading Answer the 3-4 questions here because they are about doing the evaluation Percent Error = (Exp Known)/Known *100 Consider systematic and random errors.

Determine at least two sources of error that would account for the observed density being different than the known 9. Conclusion (2 pts) Conclusion (1st person): In paragraph form, conclude the lab. Be sure you refer back to the hypothesis and purpose of the lab. Use a subheading Should refer to each purpose was the purpose met? Should comment on hypothesis was the hypothesis supported or should the hypothesis be rejected. In general, consider a percent error of 10% or lower to be a confirmation.

General Format (3 pts) Using subheadings, having all parts present and in the proper order Being readable (typed/legible), using grammar and spelling and using I only when 1st person voice is allowed. Using proper sigfigs and units on all measurements and calculations Your name and name of lab partner. Date performed and date lab report was submitted.

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