Question

4. A student determines the density of a solid with a pycnometer (see the Sample Report in Chapter I of your text) at 25.0 °C. The weight of the empty, dry pycnometer is 6.2330 g. Some of the solid material is introduced; the weight of the pycnometer plus solid is 39.4156 g. Water (density p 0.997048 g cm-3 at 25.0 °C) is added to fill all space not occupied by the solid; the weight of the pycnometer plus solid plus water is 46.1357 g. The pycnometer is emptied and filled with water only; the weight is 19.7531 g. The student's estimated 95 percent confidence limit of error in any single weighing is 0.0020 g. Calculate the density of the solid and its 95 percent confidence limit of error and present it and its limit of error in proper form with the correct number of significant figures and proper units.

Answer 1

Solution & Weight of empty day pycnometer= 6.2330 g. @ Weight of pycnometer + solia = 39.41569 b. Weight of pychnometee + solid + waters 461357 g-© Weight of pychnometert water = 19.7531 gm ar - Density of wate8 = 0.997048 oglan at 25°C. Density = mass lo t - Volume Only weigh of wate? - pychnometer + wates) - & pychnometer i Volume = 19.7531- 6.2330 = 13.520lgn of pychnometer & Density of water 13.520 DE M = mass of water 0.990 volume of pychnometa = 13.5607 cm3 -6 Weight of solid = (pychnometex toolid)-fychnometa) = 39.4156 g -6.233 0 2 Weight of solid = 3.1826 gm @ Weight of water in pychander = Pt wts) + (P+) on - containing (Pt wts) = 46.1357–989.4156 = 6.7201 qoo .

uwon 8- in (PtWts) min in ume of wate8 - Mass = 6.7201 s from Density o.9970 = 6.7403 cm3 -6 Volume of solid in (wts) = (wts)-(W) = 13.5607 -6.7403 = 6.8204 cm3 Density of solid = mass Volume = 33.1826 6.8204 Density of solid = 4.8651 91 cm3 at 25°C I te At 95% confidence limit error in weight is 0.0020 g. Higher limit Lower limit Densitys Mt 0.0020 Density - M-0.0020 - • 33.1826 +00020 = 33.1826-0.0020 6.8204 6.8204 = 33.1846 = 33.1800 6.8204 6.8204 = 4.8654 glom = 4.8648 g/cm3 so at 95% confidence limit densities are between limit o 4.86 48 g/cm3 to 4.8654 g/cm ILUL 968