Chemistry+Lab+Reports

= **The Chemistry Laboratory Report**  = = = ** // __Purpose:__ // ** A laboratory notebook should be used to explain laboratory procedures, record all laboratory data, show how calculations are made, discuss results of an experiment, and to explain the theories involved. A record of laboratory work is an important document that will show the quality of the laboratory work that you have done. As you record information in your notebook, keep in mind that someone who is unfamiliar with your work should be able to use your notebook to evaluate your laboratory experiences in chemistry.

** // __Requirements:__ // ** When you explain your work, list your data, calculate values and answer questions completely and in full sentences that ‘stand alone’ without restated questions. Be sure that the meaning of all statements will be obvious to anyone who reads your notebook.

** // __Before arriving in the lab__ // **, the title, problem, and procedure should be completed. A data table should also be constructed, where data can be entered as it is collected.

** // __Before leaving the lab__ // **, all data and observations should be neatly recorded. Basic calculations should be completed. After lab, complete calculations should be performed and the conclusion written.

**// __Laboratory Reports__ //****:**

1. **Title:** The title should be descriptive – just look at the lab. //Experiment 5 is not a descriptive title//.

2. **Date:** This is the date (or dates) you performed the experiment.

3. **Purpose:** A brief statement of what you are attempting to do. These are similar to the objectives.

4. **Pre-lab:** If there are any pre-lab questions, include the question and the answers here.

5. **Procedure:** A brief description of the method you are using. You may refer to the lab document for specific i nstructions, but you should include a brief statement of the method. DO not include lengthy, detailed directions. A person who understands chemistry should be able to read this section and know what you are doing. Include all chemicals used and the major equipment.

6. **Results –** Results are recorded in three parts: //Observations// – General descriptions of visible appearances or changes that occur during the experiment, such as “table salt is a white, cube-shaped crystal which dissolves in water. (Qualitative)

//Data// – Neatly arranged measured values listed in tabular form. The units of measurement MUST be included with the numerical values. The accuracy of the measurement can also be included as a range (+/-). Calculated answers that are derived by performing a simple mathematical operation can also be included in the data table. If the graphs are included, make the graphs an appropriate size. Label all axes and give each graph a title. USE A RULER to make all data tables and graphs!

//Calculations// – Show all calculations with formula and appropriate units on all numbers. Neatly demonstrate the math set-ups, including units. Label what is being calculated. –make it organized. Show error calculations where appropriate. If experiments are qualitative, this section may be omitted.

7. **Conclusions:** Make a simple statement concerning what you can conclude form the experiment. Refer back to the purpose of the lab to write this section. (i.e. How was the purpose of the experiment fulfilled?) 8. **Discussion of Theory:** In this section you should include such information as: What theory was demonstrated in this experiment (Include concepts used in the experiment)? What do the calculations show? Why does (or doesn’t) the experiment work? This section shows me that you understand the concepts used in the lab. // Be detailed and ask if you need help! //

<span style="margin-bottom: 0in; margin-left: 28.0pt; margin-right: 0in; margin-top: 0in; mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">9. **Experimental Sources of Error:** What are some specific sources of error, and how do they influence the data? Do they make the values obtained larger or smaller than they should be? Which measurement was the least precise? Instrumental error and human error exist in all experiments, and should not be mentioned as a source of error unless they caused a significant fault. Significant digits and mistakes in calculations are NOT a valid source of error. In writing this section it is sometimes helpful to ask yourself what you would do differently if you were to repeat the experiment and wanted to obtain better precision. **If you can calculate percent error, do so and include in this section.**

<span style="margin-bottom: 0in; margin-left: 28.0pt; margin-right: 0in; margin-top: 0in; mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">10. **Post-lab Questions:** Answer any questions included in the lab. Answer in such a way that the meaning of the question is obvious in your answer.

<span style="margin-bottom: 0in; mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;">**A note about the purpose of laboratory reports:** <span style="margin-bottom: 0in; mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;"> • Reports give enough information so someone could repeat the lab. This will include showing how calculated values were obtained. <span style="margin-bottom: 0in; mso-layout-grid-align: none; mso-pagination: none; tab-stops: 28.0pt 56.0pt 84.0pt 112.0pt 140.0pt 168.0pt 196.0pt 224.0pt 3.5in 280.0pt 308.0pt 336.0pt; text-autospace: none;"> • Reports give you an opportunity to reflect on the laboratory experience and ponder the meaning of the lab. You should understand what you did and why you did what you did.