Chemistry Baseline Cornerstone Assessment The Cornerstone Assessments were developed with support through the VDOE Mathematics and Science Partnership Grant Program NCLB Title II, Part B program by high school teachers as a part of the Old Dominion University Learning Enhanced through the Nature of Science (LENS) project. 2012 2013 This assessment consists of two parts. DIRECTIONS to provide to read to students: Today you will be taking the Chemistry Baseline Cornerstone Assessment to find out your skills in scientific investigation, data analysis and interpretation, and scientific reasoning. Read each question carefully and provide your best answer or response. Record your answers directly on the spaces provided in the assessment. Be sure your work and responses are legible. Chemistry Baseline Cornerstone Assessment Version 1 1
Chemistry Baseline Cornerstone Assessment: Part A. Experimental Design Directions: Read the paragraph below and then respond to the questions. Hydrogen peroxide is a liquid that breaks down and releases bubbles of oxygen gas. By adding a catalyst, this chemical reaction occurs faster and is completed more quickly. Patty uses a hydrogen peroxide product with a catalyst to clean her contact lenses every night, and she has to wait until morning for the bubbles to stop forming so she knows the reaction is finished. Patty wants to design an experiment to determine the effect of varying the amount of a catalyst on how fast this reaction occurs. Patty obtains a 500 ml bottle of hydrogen peroxide and 25 grams of the catalyst. 1. What should be the independent variable in Patty s experiment? Explain your choice. 2. What should be the dependent variable in Patty s experiment? Explain your choice. 3. State an appropriate hypothesis for Patty to test. Explain your hypothesis. 4. What condition(s) should remain constant in this experiment? Explain your choices. Chemistry Baseline Cornerstone Assessment Version 1 2
5. A well designed experiment must have a control for comparison purposes. Identify an appropriate control for this experiment. Justify your answer. 6. Design a procedure for Patty to carry out to determine the effect of varying the amount of catalyst on the rate of the reaction. List the steps below and the materials needed. 7. Create a data table that can hold all the data you would gather through your procedure. Chemistry Baseline Cornerstone Assessment Version 1 3
Chemistry Baseline Cornerstone Assessment: Part B. Data Interpretation and Analysis and Scientific Reasoning Directions: Read the paragraph below and review the data table. Then, answer the questions that follow. Patty carries out an experiment by measuring out 25 ml of hydrogen peroxide into each of five test tubes. She leaves the first one without any catalyst in order to create a control condition. Then she adds an increasing amount of catalyst (0.5 g, 1.0g, 1.5g, and 2.0g) to four of the test tubes. She starts the stopwatch when the catalyst has been added and lets the reactions proceed until they stop bubbling. When each reaction stops bubbling, Patty notes the time on the stopwatch and records it in her data table. She then repeats the all five reactions two more times. Time Amount of catalyst Trial 1 Trial 2 Trial 3 Average time 0 g 10 hours 11 hours 10 hours hrs 0.5 g 6 hours 7 hours 5.7 hours hrs 1.0 g 2 hours 3.5 hours 1.9 hours hrs 1.5 g 45 minutes 48 minutes 53 minutes min hrs 2.0 g 44 minutes 48 minutes 54 minutes min hrs 1. Calculate the average time for each amount of catalyst. Show your calculations in the space provided below and follow significant digit rules. Then, write the answer in the blank column of the data table. 2. To graph the data, the time must be in the same units. Convert average time in the final two reactions to hours. Show your calculations in the space provided below and follow significant digit rules. Then, write your answers in the data table. Chemistry Baseline Cornerstone Assessment Version 1 4
3. Create a graph showing the relationship between the amount of catalyst and the average time the reaction took. Graph the data on the grid below. Be sure to label and correctly scale the axes and give the graph a title. 4. Examine the data. How does the amount of catalyst affect the reaction time? 5. What do you think the time of reaction will be when 2.5 grams of catalyst is used? Explain your answer using the data. 6. Patty hypothesized that increased catalyst would decrease the time taken for the reaction. Based on this experiment, do you accept or reject her hypothesis? Explain your decision. Chemistry Baseline Cornerstone Assessment Version 1 5
7. After completing her experiment, Patty tested the balance she used to measure out the amount of catalyst. She placed a 10-gram weight on the balance, and the balance read out 11 grams. Based on this new information, how would the data Patty gathered change? Would you change your interpretation of the data (question #4)? Explain why or why not. Chemistry Baseline Cornerstone Assessment Version 1 6