Determination of nickel percentage: the concentration of nickel in your purple nickel compound is determined spectrophotometrically using the spectrovis. three standards are provided to make the calibration curve. before obtaining the standards, prepare your sample containing the purple nickel compound. weigh 1-1.5 g of your nickel compound on an analytical balance, transfer to a 100-ml volumetric flask, dissolve in 1 m h2so4, and carefully dilute to the 100 ml mark with 1 m h2so4. invert the flasks several times to ensure uniform concentration. once you have prepared your sample, log into logger pro and calibrate the spectrovis using dih20 as the blank. set the wavelength to 400 nm. record the concentration of the standards and their absorbances as well as the absorbance of the solution you prepared. create a beer's law graph plotting absorbance on the y-axis and concentration of ni2+ on the x- axis only including your three standards. do not include your purple nickel sample in the calibration curve. if the line appears straight, then have the computer draw a regression line. if it appears curved, consult your instructor. from the graph, determine the concentration of ni2 in 76 your sample. the concentration and volume should give moles, which can be converted to grams, and then, knowing your original sample mass, the % ni in the compound.