Materials – double salt (self-made & EIU Chemistry Stockroom), 6 M HCl (EIU Chemistry Stockroom), 10% BaCl2, 6 M HNO3 (EIU Chemistry Stockroom)
Equipment – Ocean Optics Spectrometer USB4000, Logger Pro
Procedure – In order to find the mass percent of the sulfate, the sulfate needed to separate itself from the rest of the double salt. To do this, experimenters began by weighing out 0.998 g of the double salt into a 250-mL beaker. They then used the graduated cylinder to add about 150 mL of deionized water and 2 mL of the 6 M HCl into the 250-mL beaker. As they added the deionized water to the salt, it dissolved relatively quickly with the help of a glass stirring rod. As they dissolved the solution, it turned to a clear light …show more content…
They added about 20 mL of deionized water to the salt and stirred the solution until it dissolved. As it dissolved, the solution turned into a light blue color. Then to make sure that very little of the solution was left on the stirring rod, they rinsed it with more deionized water into the beaker. After thoroughly rinsing a 50-mL volumetric flask with deionized water, they transferred the solution into this flask and rinsed the 100-mL beaker with deionized water in order to ensure as much of the solution was transferred to the flask as possible. They filled the remainder of the flask with more deionized water, placed a rubber stopper into the top of the flask, and inverted it 20 times in order to mix the solution. In order to measure the absorbance of this solution, the beginning absorbance was set at 785.1 nm. Experimenters filled a cuvette with water until the water filled about two thirds of it, and then, after wiping it dry with a Kimwipe and handling it only by the frosted sides, placed it in the compartment of the spectrometer in order to calibrate it, with the transparent side of the cuvette aligned with the white line next to the compartment. To calibrate it, they selected “Experiment” from the main toolbar on Logger Pro, selected “Calibrate: Spectrometer 1,” clicked “Skip Warm Up,” and finally clicked “Finish” and then “OK.” Once calibrated, they threw out the water in the cuvette and shook out as much as they could of the remaining water residue. They then rinsed the cuvette with the solution, discarded that, rinsed it two more times, and then filled about two thirds of the cuvette with this solution. After again using a Kimwipe, handling it by the frosted sides, and placing the cuvette in the compartment, they recorded the absorbance displayed on the screen, which was 0.232 nm for this