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Chemistry 141

Chemistry 141. Laboratory Information. Lab Books. Get a lab book with prenumbered carbonless copy pages. Write your name on the front of the lab book. All data in the lab book must be written in blue or black ink.

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Chemistry 141

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  1. Chemistry 141 Laboratory Information

  2. Lab Books • Get a lab book with prenumbered carbonless copy pages. Write your name on the front of the lab book. • All data in the lab book must be written in blue or black ink. • Do not tear any original pages out of the book, unless you are turning them in!!

  3. No writeovers 375.788g No obliterations 639.824g No Erasing Cross out once and rewrite. 4.932g 5.382g Be sure to write all data in your lab book in black or blue ink when you take the data. The only exception will be for data collected by the computer. Any data recorded on stray pieces of paper will be confiscated! Lab Books 636

  4. For the prelab: Complete the header Write a title, objective, procedure reference, safety, and waste treatment. Get is signed off before beginning your experiment. Everyone will do the entire lab on their own, but you may want to work with someone else to compare your results. Title e.g. Experiment 1 – Standard Deviation Lab Objective Procedure Safety Waste Treatment Lab Books BeN FrON Instructor

  5. Write the objective of the experiment. Why are you doing this experiment? Objective: To determine the accuracy and precision of glassware and to calculate the standard deviation. To determine the density of… Lab Books

  6. If you followed the procedure outlined in the handout provided in lab then reference the procedure, leave space for changes note any safety precautions note the waste treatment Procedure: Lehman, J. et al (2012). “Experiment 1: Measuring Density with Different Types of Glassware”, Grossmont College, Chemistry 141 Laboratory Manual (6th Edition, pp 1-12) El Cajon, California. Part B Procedure (You will make up your own, but sure to note it here). Safety: Wear safety glasses Waste Treatment: n/a Lab Books

  7. Lab Books Data and Observations: • This should be a log of what you saw along with any tables of data that may be necessary. • Another student should be able to pick up your lab notebook and repeat your experiment. • Be sure to draw and label the equipment used. • Uncertainty of beaker ± 1 mL • Temperature of water 23.8 °C • Density of water from CRC Handbook 82nd edition of 0.9973485 g/mL. • Used Balance Number 1376 • I filled the beaker to the 50 mL line with an eyedropper. It was very difficult to determine when the water level reached the line on the beaker. • Etc…

  8. At the end of the lab period, sign and date your lab book after your last data entry and get an instructor stamp. Copper sulfide precipitate was filtered and left in lab drawer to dry. The precipitate was a very fine black powder. BeN FrON Instructor Lab Books

  9. Typewritten reports documenting your experimental results. Some reports will be abbreviated as noted in write-up instructions. Be sure to clearly label each section! Title Page Objective Introduction Procedure Results and Calculations Discussion Conclusion Questions Lab Reports

  10. This will identify the experiment, you, the course, your class, your instructor, and the date(s) the experiment was performed. Very important so I can keep track of what you are handing in! Standard Deviation Experiment Fun with Glassware! Jane Doe Lab Partner: John Smith Chemistry 141 Section 5399 Instructor: BeN FrON August 29, 2007 completed September 7, 2007 turned in Lab Reports: Title Page

  11. Restate objective from lab book, but make sure to update it to make it more specific is something was left out. Objective: To determine the accuracy and precision of laboratory glassware and to learn how a standard deviation is calculated. To determine the density… Lab Reports: Objective

  12. This section tells a little bit about the theory of the experiment and how it will be done. Be sure to give each equation and/or reaction it’s own line and label is eq. 1, eq. 2, rxn 1, rxn 2, etc…so that you can refer back to then by number later in your report. Introduction: When doing scientific experiments it is always necessary to minimize the error where possible. Unfortunately, however, it is impossible to completely avoid error. In experiments there are several types of error. They are random error, systematic error, and gross error. Random error is--- Lab Reports: Introduction

  13. Reference the procedure used and note any deviations from the published procedure. Procedure Followed procedure from handout: Lehman, J. et al (2012). “Experiment 1: Measuring Density with Different Types of Glassware”, Grossmont College, Chemistry 141 Laboratory Manual (6th Edition, pp 1-12) El Cajon, California. Part B: Density of Coke and Diet Coke Selected most accurate and precise piece of glassware the… … Note any changes e.g. In this experiment the liquid used for the density determinations was an isopropanol/water mixture. Lab Reports: Procedure

  14. Lab Reports: Results and Calculations • A table summarizing major data like the one shown. • For non numerical labs, summarize the data generated. Results and Calculations

  15. Lab Reports: Results and Calculations Results and Calculations • The minor data is on the spreadsheet, which will also be turned in: • Found at www.grossmont.edu/dianavance • Show sample calculations for each type of calculation. (These may be hand written.) Sample Calculation for mass liquid: xxx.xxg-xx.xxg=xx.xxg

  16. This is where you get to explain your results. Be sure to include quantitative numerical data where appropriate. e.g. average mass/volume, standard deviation, true value, percent error Be sure to include qualitative descriptions where appropriate. e.g. precipitate was a fine, white powder. Evaluate your data e.g. precision and accuracy Your sources of experimental error in your discussion must be supported by your running log in your data and observations section in your lab notebook. Discussion: The average mass of water held by the beaker was 43.2 g with a standard deviation of 0.1 g. This was less than expected based on the marking on the beaker which have an uncertainty of ± 1mL. The mass of water held was probably low because I filled my beaker to the bottom of the line and it may have been designed to fill to the top of the line. I also noticed that… Lab Reports: Discussion

  17. This is where you give the final result and evaluate your objective. This is essentially the punch line-- Conclusion The beaker held 53.4 grams of water with a standard deviation of 0.7 g with good precision and a percent error of 6.8%, so fair accuracy. The graduated cylinder… Lab Reports: Conclusion

  18. Lab Reports: Questions • Answer any questions posed in the lab here or on the sheet(s) provided in the lab manual.

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