Question

2. Make buoyancy corrections for the weights in part 1 to determine the real mass of each sample of water. Use the buoyancy correction equation, assuming the balance weights have a density of 8.0 g/mL. Use the density of water determined from the appendix (the temperature is 22°C). The Density of Water at 22 degrees Celsius is 0.9977735 (g/mL).

1. Using a 25-mL volumetric transfer pipet, pipet 25 mL of DI water into a dry, pre-weighed, conical flask or a beaker and weigh the sample. Use an analytical balance (± 0.0001 g) to make these weighings. Read and carefully follow the "Analytical Balance" instructions. Repeat 3 times. Calculate the average value of your measurements and the standard deviation.

W_vac = W_air + W_air [(0.0012/D_o)-(0.0012/D_w)]

W_vac = weight in vacuum, g; W_air = weight in air, g

D_o = density of object; D_w = density of weights

0.0012 = density of air

This table shows the results of the 25 mL transfer:

25-mL Trial #	Mass of flask (without water)	Mass of flask (with water)	Mass of the water (Difference in masses)
1	48.0485 g	72.6685 g	24.6200 g
2	51.5100 g	76.2950 g	24.7850 g
3	55.2756 g	80.1296 g	24.8540 g

Average value: 24.5730 g

Standard Deviation: 0.0981733 g

This table shows the results of the 10 mL transfer:

10-mL Trial #	Mass of flask (without water)	Mass of flask (with water)	Mass of the water (Difference in masses)
1	48.0167 g	57.9463 g	9.9295 g
2	52.0842 g	62.0142 g	9.9300 g
3	55.2745 g	65.2300 g	9.9555 g

Average Value: 9.9383 g

Standard Deviation: 0.12140 g (five significant figures within the mass of water).