LAB REPORT The purpose of lab report is to: 1) record changes in variables 2) communicate observations 3) interpret observations. Parts of the Laboratory Report Experiment title on a title page Although self explanatory, the title helps you, as the student, define your understanding of the laboratory experiment. The title page also indicates the names of the lab partners, the date the report was handed in and the course number. Purpose A brief description (in your own words) of what scientific principle is to be tested or verified. The purpose of a lab experiment is to test a hypothesis. In most of our labs, you will be given a question or a hypothesis to design your own procedures to test. Materials and Method (Procedure) First, list all the materials that will be needed to carry out the experiment. Then, briefly outline of the experimental procedure. A detailed report of all the steps taken is not necessary. By including a procedure outline in the report your attention is focused on what happened during the experiment. If the procedure is provided to you, you must note any modification made to that procedure. Try to avoid writing your procedures using the past tense or passive form. Data Collection Presentation of data in tables allows easy following of the coming data manipulations. Tables should be clearly labelled as to their content and numbered for ease of referral in the discussion section. Therefore, some estimation of the experimental uncertainty is necessary to help explain the results and to verify if the scientific principle tested holds. Part of the data may involve making observations (color changes, temperature changes, melting point, boiling point, the physical appearance of a chemical substance, etc.) Results Calculations, result table and graphs are ways to express results. Experimental error analysis Some of your lab questions might have answers that have been repeatedly obtained and generally accepted as correct. This number would be called the theoretical value. When you perform an experiment and get a number, that number would be called the experimental value. When a theoretical value is known, you can determine just how good your experiment is and how well your procedures were done by using the following equation to calculate the experimental error. % error: theoretical value – experimental value theoretical value Discussion This section requires looking at the experiment’s purpose, the data, the graph and the calculation sections of the lab report and bringing them all together. Sometimes it involves the comparison of the student's experimentally derived answer to a known literature value. Other times, it requires the student to identify an unknown from a list of unknowns based on the information gathered during the experiment. Sometimes, you will be asked a series of questions that should guide your thinking. In the discussion section. Conclusion Summarize the essential lab data. Show how the essential data answers the hypothesis/purpose of the experiment. Identify the one area of the lab most likely responsible for measurable experimental error.