The reaction of bromine with acetone follows first order kinetics, i.e where k is the rate constant, c is the concentration at time t and c0 is the initial concentration. The absorbance of bromine can be followed to determine the rate constant. The absorbance is related to concentration by Beer's Law A = ebc where e is the molar absorptivity, b the path length and c the concentration. An aqueous solution of acetone and bromine was mixed in a 1 cm quartz cell of and the absorbance was measured at 532 nm. Initially the absorbance was 0.98 and at 120 s it was 0.76. The error in the absorbance reading was 0.02 absorbance units, the timer could be read to within 1 sec, and the tolerance of the cell was 0.5 mm. Given that the molar absorptivity of Br2 in water at 532 nm is e = 5512 L mol-1 cm-1 calculate the rate constant for the reaction and report it with error limits and proper significant figures