Inorganic Double Salt Lab Report

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In this experiment, the percent composition of the inorganic double salt was found. Various methods were used to break down the double salt so that a mass percent could be found. There were four different methods used to find the individual percents that made up the double salt. First, the percent of potassium was given (17.9%).
Second, the percent of Ni2+ was found. This involved multiple steps and was the most involved part of the experiment. A chart and graph were made from the values that part D of the experiment produced. A line of best fit was made and came out to be y=66.167x+0.0081. Using the absorbance value of the double salt (0.234) as X, the concentration came out to be .004314 g/mL. This value was multiplied by fifty. It was …show more content…

This was found by taking the mass of the evaporated water (0.250 g) and dividing it by the amount of salt in the crucible (1.017 g). This gave the amount of water in one gram of salt as 0.246 g. This number was multiplied by 100 percent, yielding a percent composition for water as 24.6%.
Finally, the amount of sulfate (SO4) was calculated. This took several conversion factors to complete. The mass of barium sulfate isolated in the filter paper was 1.132 g. This number was multiplied by the fraction of in SO4 (96.06 g) in 1 mole of BaSO4 (233.3 g). This gave the mass of 0.4661 g of SO4 in the amount of the sample used in part B of the experiment (1.026 g). It was then divided by that amount and multiplied by 100 yielding a percent composition of 45.4% SO4.
Using these percents, the molecular formula of the double salt could be determined. The percent values were converted to gram values and then divided by their molar mass, yielding how many moles of the double salt were present in 100 g of the sample. Those values were then divided by the smallest value (0.2897) to create a simple ratio of the components of the double salt. The mole values were as follows; 1.631 mole SO4, 4.718 mole H2O, 1.580 mole K, 1 mole Ni2+. These values were rounded to their nearest whole number, creating the empirical formula of the double salt, K2 Ni (SO4)2 (H2O)5. It was instructed to use the empirical formula as the molecular formula, …show more content…

Many steps were taken it minimize error, but error may have altered results regardless. Starting at the beginning of the experiment, one place that error could have occurred was in the recording of data. There were numerous places that this could have happened, such as when taking the mass of the double salts or when taking the mass of the crucible and lid. Further on in the experiment, there was a chance of error when trying to extract the last bit of barium sulfate from its beaker into the funnel. Also mass could have been lost on the glass stirring rod. There were two times in the experiment where substances had to be transferred from a funnel to a watch glass. Error could have occurred here from substances falling off of the filter paper or watch glass. In part C of the experiment, while trying to evaporate only the water, the double salt could have been overheated. Overheating the contents of the crucible was a concern, it would cause the loss of mass other than water. Finally, at the end of the experiment, when using the spectrometer, if the nickel solution had not been stirred enough it would cause the results to be

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