IENMISTRY FREE-RESPONSE QUESTIONS NayC3,HyNS,o, + ocr products blue 5. Blue food
ID: 978211 • Letter: I
Question
IENMISTRY FREE-RESPONSE QUESTIONS NayC3,HyNS,o, + ocr products blue 5. Blue food coloring can be oxidized by household bleach (which contains OCT) to form colorless products, as colorless br ksr represented by the equation above. A student used a spectrophotometer set at a the absorba large excess so that the concentration of OCI is essentially constant throughout the reaction. The student used data from the study to generate the graphs below. wavelength of 635 nm to study nce of the food coloring over time during the bleaching process. In the study, bleach is present in 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.04 45 40 -0.5 815 25 20 15 10 -3.0 -3.5 0 20 40 60 80 100 Time (s) e6s) 80 10040 0 20 40 60 80 100 Time (s) 0 20 40 60 80 100 Time (s) Graph I Graph 11 Graph ITI (a) Based on the graphs above, what is the order of the reaction with respect to the blue food coloring? (b) The reaction is known to be first order with respect to bleach. In a second experiment, the student prep solutions of food coloring and bleach with concentrations that differ from those used in the first experi When the solutions are combined, the student observes that the reaction mixture reaches an absorbanc zero too rapidly. In order to correct the problem, the student proposes the following three possible modifications to the experiment. .Increasing the temperature tIncreasing the concentration of the food coloringExplanation / Answer
a) From the graphs the order of reaction is first order kinetics. (b)1) As temperature increases initially rate of reaction also increasesas the reaction is of first order.2) Also by increasing the concentration of food coloring rate of reaction initially increases but later it get retarded the rate of reaction.3)As per first order kinetics conc.of bleach increases rate of reaction increases but after inceasing the number of bleach molecules again it slows down. c) For red food coloring student should modify the wavelength of spectrophotometer.