Lab - Rate of Change Reactions Physical Science
Lab Report Guide Directions Now that the lab is complete, it’s time to write your lab report. The purpose of this guide is to help you write a clear and concise report that summarizes the lab you have just completed. The lab report is composed of three sections: Section I: Experimental Overview · Provide background information. · Include the hypothesis. · Summarize the procedure. Section II: Data & Analysis · Include graphs to display trends in the data. · Identify trends in the data. Section III: Conclusions · Identify if the hypothesis was supported or refuted. · Provide logical reasoning based on data. · Explain how the experiment could be improved. To help you write your lab report, you will first answer the eight questions listed below based on the experiment that you have just completed. Then you will use the answers to these questions to write the lab report that you will turn into your teacher. You can upload your completed report with the upload tool in formats such as OpenOffice.org, Microsoft Word, or PDF. Alternatively, your teacher may ask you to turn in a paper copy of your report or use a web-based writing tool. Questions Section I: Experimental Overview 1. What is the question that you are trying to answer? 2. What is your hypothesis for this experiment? 3. What methods are you using to test this hypothesis? Outline the steps of the procedure in full sentences. Section II: Data & Analysis 4. What graphs would clearly represent the trends in your data? Your Student Guide includes information on which graphs to construct. Each graph should have the following: a. an appropriate title b. appropriate labels for each axis c. an appropriate scale for each axis d. the correct units for the data Complete a rough sketch of each graph. 5. What do the data in your graphs tell you? Explain in one or two sentences what trend the reader should observe in each of your graphs. Section III: Conclusions 6. What do the data tell you about your hypothesis? State how your hypothesis is either supported OR refuted by the data. 7. How do the data support your claim above? Explain your statement above. Be sure to refer to specific pieces of data from your experiment that support your argument. 8. If you could repeat the experiment and make it better, what would you do differently and why? There are always ways that experiments can be improved. Now that you are a veteran of this experiment and have experience with the procedure, offer some advice to the next scientist about what you suggest and why. Writing the Lab Report Lab Report Guide Lab Report Guide Now you will use your answers from the eight questions above to write your lab report. Follow the directions below. Section I: Experimental Overview Use your answers from questions 1-3 as the basis for the first section of your lab report. This section provides your reader with background information about why you conducted this experiment and how it was completed. It should be 1-2 paragraphs in length. Section II: Data & Analysis Use your answers from questions 4-5 as the basis for the second section of your lab report. This section provides your reader with the data from the experiment and a visual way to see any trends in the data. No paragraphs are required for this section, but you do need to include the appropriate graphs to display the data. Section III: Conclusions Use your answers from questions 6-8 as the basis for the third section of your lab report. This section provides your reader with your interpretation of the data set. It also demonstrates your understanding of the experiment through your ability to offer constructive criticism about its design. This section should be 1-2 paragraphs in length. Overall When complete, the lab report should be read as a coherent whole. Make sure that you connect different pieces with relevant transitions. Review for proper grammar, spelling, punctuation, formatting, and other conventions of organization and good writing. 2 Lab: Rate of Chemical Reactions Student Guide Student Guide (continued) Pre-Lab Information PurposeExplore the effects of variables on the rate of chemical reactions. TimeApproximately 45 minutes QuestionHow do the factors of temperature and surface area affect the rate of chemical reactions? HypothesisIf temperature and surface area increase, then the time it takes for sodium bicarbonate to completely dissolve will decrease, because increasing both factors increases the rate of a chemical reaction. VariablesIndependent Variable #1: Temperature of the water Independent Variable #2: Surface area of the sodium bicarbonate Dependent Variable: Time to dissolve sodium bicarbonate SummaryYou will establish a baseline for comparison by adding a tablet of sodium bicarbonate to room temperature water and recording the amount of time necessary for it to completely dissolve. You will then repeat the procedure in one series of trials in which you use different temperatures and another series of trials in which you manipulate the available surface area of the tablets. Each time, you will record the time it takes for the sodium bicarbonate to dissolve and compare it to your baseline. Safety Wear appropriate clothing for working in the lab, including a lab coat or apron. Wear protective gloves when handling chemicals and wash your hands thoroughly when the experiment is complete. Protect your eyes by wearing safety goggles throughout the experiment. Inspect glassware prior to starting your experiment. Check for chips, cracks, or other safety concerns. Behave in a way that is purposeful. Report all accidents – no matter how big or small – to your teacher. Lab Procedure Gather Materials one 400 mL beaker 15 sodium bicarbonate tablets water stir rod graduated cylinder thermometer stopwatch spatula mortar and pestle Establish Baseline for Comparison (Room Temperature Water) Use a graduated cylinder to add 250 mL of room temperature water to a beaker. Stir the water with a stir rod to make sure it is the same temperature throughout the beaker. Record the temperature of the water in Table A. Reset the stopwatch to zero. If you do not have a stopwatch, note the time on the clock. Add 1 sodium bicarbonate tablet to the beaker of water and start the stopwatch. Carefully watch the tablet as it dissolves. When the tablet can no longer be seen, press stop on the stopwatch. Record the time required for the tablet to fully dissolve in Table A. Dispose of the solution and rinse out the beaker for the next step. Increase Accuracy of Baseline Measurement (Room Temperature Water) Repeat steps 2a–2g two more times and record your measurements of the time required to dissolve the tablet in Table A. Note any changes to temperature as well. Add up your measurements and divide by the number of trials to determine the average amount of time required for the tablet to fully dissolve. Record the average time in Table A. Determine the Effect of Temperature on Reaction Rate (Hot Water) Use a graduated cylinder to add 250 mL of hot water to a beaker. Stir the water with a stir rod to make sure it is the same temperature throughout the beaker. Record the temperature of the water in Table B. Reset the stopwatch to zero. If you do not have a stopwatch, note the time on the clock. Add 1 sodium bicarbonate tablet to the beaker of water and start the stopwatch. Carefully watch the tablet as it dissolves. When the tablet can no longer be seen, press stop on the stopwatch. Record the time required for the tablet to fully dissolve in Table B. Dispose of the solution and rinse out the beaker for the next step. Repeat steps 4a–4g two more times to increase the accuracy of your measurement. Record your data in Table B. Calculate the average time for the tablet to dissolve under these conditions and record it in Table B. Determine the Effect of Temperature on Reaction Rate (Cold Water) Use a graduated cylinder to add 250 mL of cold water to a beaker. Stir the water with a stir rod to make sure it is the same temperature throughout the beaker. Record the temperature of the water in Table C. Reset the stopwatch to zero. If you do not have a stopwatch, note the time on the clock. Add 1 sodium bicarbonate tablet to the beaker of water and start the stopwatch. Carefully watch the tablet as it dissolves. When the tablet can no longer be seen, press stop on the stopwatch. Record the time required for the tablet to fully dissolve in Table C. Dispose of the solution and rinse out the beaker for the next step. Repeat steps 5a–5g two more times to increase the accuracy of your measurement. Record your data in Table C. Calculate the average time for the tablet to dissolve under these conditions and record it in Table C. Determine the Effect of Surface Area on Reaction Rate (Quarters) Use a spatula to break 1 sodium bicarbonate tablet into 4 pieces. Use a graduated cylinder to add 250 mL of room temperature water to a beaker. Stir the water with a stir rod to make sure it is the same temperature throughout the beaker. Record the temperature of the water in Table D. Reset the stopwatch to zero. If you do not have a stopwatch, note the time on the clock. Add the 4 smaller sodium bicarbonate pieces to the beaker of water and start the stopwatch. Carefully watch the pieces as they dissolve. When the pieces can no longer be seen, press stop on the stopwatch. Record the time required for all of the pieces to fully dissolve in Table D. Dispose of the solution and rinse out the beaker for the next step. Repeat steps 6a–6h two more times to increase the accuracy of your measurement. Record your data in Table D. Calculate the average time for the tablet pieces to dissolve under these conditions and record it in Table D. Determine the Effect of Surface Area on Reaction Rate (Crushed) Use a mortar and pestle to crush 1 sodium bicarbonate tablet into a fine powder. Use a graduated cylinder to add 250 mL of room temperature water to a beaker. Stir the water with a stir rod to make sure it is the same temperature throughout the beaker. Record the temperature of the water in Table E. Reset the stopwatch to zero. If you do not have a stopwatch, note the time on the clock. Add the sodium bicarbonate powder to the beaker of water and start the stopwatch. Carefully watch the powder as it dissolves. When the powder can no longer be seen, press stop on the stopwatch. Record the time required for the powder to fully dissolve in Table E. Dispose of the solution and rinse out the beaker for the next step. Repeat steps 7a–7h two more times to increase the accuracy of your measurement. Record your data in Table E. Calculate the average time for the powder to dissolve under these conditions and record it in Table E. Summarize Data Transfer your data for volume, temperature, and the calculated averages from Tables A–E to the Summary Tables F and G for easy comparison of each of the variables. Construct Graphs Follow these directions to construct graphs of your data. Sketch your graphs in your Lab Report Guide, Section 2. Construct a bar graph that compares the average time to dissolve the sodium bicarbonate for the three temperatures that you calculated to determine whether temperature does have an effect on the rate of a chemical reaction. Construct a bar graph that compares the average time to dissolve the sodium bicarbonate for the three different surface areas that you calculated to determine whether surface area does have an effect on the rate of a chemical reaction. Data Record your data in the tables below. Table A: Baseline Data for Tablet in Room Temperature Water Volume (mL) Temp. (oC) Start Time End Time Elapsed Time (s) Trial #1 250 mL 20°C 0.00 50.70 Trial #2 250 mL 20°C 0.00 52.00 Trial #3 250 mL 20°C 0.00 51.00 Average Time for Tablet to Dissolve 51 Table B: Time to Dissolve Tablet in Hot Water Volume (mL) Temp. (oC) Start Time End Time Elapsed Time (s) Trial #1 250 mL 40°C 00.00 22.00 Trial #2 250 mL 40°C 00.00 24.00 Trial #3 250 mL 40°C 00.00 20.00 Average Time for Tablet to Dissolve 22 Table C: Time to Dissolve Tablet in Cold Water Volume (mL) Temp. (oC) Start Time End Time Elapsed Time (s) Trial #1 250 4°C 00.00 84.00 Trial #2 250 4°C 00.00 89.00 Trial #3 250 4°C 00.00 85.00 Average Time for Tablet to Dissolve 86.00 Table D: Time to Dissolve Tablet When Quartered Volume (mL) Temp. (oC) Start Time End Time Elapsed Time (s) Trial #1 Trial #2 Trial #3 Average Time for Tablet to Dissolve Table E: Time to Dissolve Tablet When Crushed Volume (mL) Temp. (oC) Start Time End Time Elapsed Time (s) Trial #1 Trial #2 Trial #3 Average Time for Tablet to Dissolve Summary Tables Table F: Summary Table for the Effect of Temperature Volume (mL) Temp. (oC) Average Time (s) Hot Water Room Temperature Cold Water