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Experiment A1

A. Weighing by Difference and the Mole Concept Results 5.48 g = mass of vial + Carbon 4.45 g = mass of empty vial 1.07 g = mass of carbon transferred to beaker 5.69 g = mass of vial + tin 4.41 g = mass of empty vial 1.28 g = mass of tin transferred to beaker Calculations 0.089 mol Carbon = amount of carbon transferred to beaker (in moles) 5.36 x 10^22 Atoms of carbon = Amount of Carbon atoms transferred to beaker 0.0108 mol Tin = amount of tin transferred to beaker (in moles) 6.49 x 10^21 Atoms of Tin = Amount of tin atoms transferred to beaker 1. 1.995 x 10^-23 2. 19.71 x 10^-23 > 1.971 x 10^-22 3. 1.995 : 19.71 ratio of 1 :10 In theory the ratio would be 1 gram carbon to 10 grams tin. B. Density of Water 25.5 mL = volume of water in cylinder 50.33 g = mass of water + cylinder 25.42 g = mass of empty cylinder 24.91 g = mass of water in cylinder 23 degrees celsius = water temperature

Density of water at 23 degrees celsius = 24.91g / 25.5 mL = 0.97686 g/mL 0.99754 g/mL = Literature value for the density of water at this temperature. Reference: Table A1.1

C. Calibration of a Pipette

Set 1 - (43.78 – 38.33) = 5.45 v mL Set 2 – (44.05 – 38.33) = 5.72 v mL Set 3 – (43.62 – 38.33) = 5.29 v mL Set 4 – (44.35 – 38.33) = 6.02 v mL Set 5 – (44.46 – 38.33) = 6.13 v mL Temperature of water = 22 degrees celsius Density of water at temp = .99777 g/mL Total Volume dispensed = 28.61 mL Average Volume dispensed = 28.61 mL / 5 trials = 5.722 mL Deviation set 1 – (5.722 – 5.45) = 0.272 Deviation set 2 – (5.722 – 5.72) = 0.002 Deviation set 3 – (5.722 – 5.29) = 0.432 Deviation set 4 – (5.722 – 6.02) = -0.298 Deviation set 5 – (5.722 – 6.13) = -.408 Average Deviation = 1.0232(sum of each deviation)/5(number of trials) = 0.20464 Standard deviation = Sqr root ((1.0232)^2/5-1)= .5116

Questions 1. The remaining powder is not important due to weighing by difference. A measurement is taken with the vial “empty” and sets a baseline. When the next powder is introduced and weighed, it already has taken into account the weight of the previous powder and the new powder can be measured. This method allows results to still be valid. 2. If the cylinder contained a few more drops of water during its initial measurement when it should be clean and dry then the weighing by difference would be off. If the weighing by difference is off, then that would result in an inaccurate measurement when water is added and measured which leads to an inaccurate density result....