DENSITY AND SPECIFIC GRAVITY
Materials and Methods
Part 1: Density of an Unknown Solid
1. We first were asked from our laboratory instructor to attain an unknown solid and were asked to note down the number of the solid. 2. Determine the mass of the unknown solid to the nearest 0.001 g and record it in the data table in the back of the laboratory workbook. 3. Then we determined the volume of the unknown solid by water displacement. We first filled a 100mL graduated cylinder about 1/3 of the way with water and we recorded the volume to the nearest 0.1mL. We carefully slid the unknown solid into the cylinder with water. We then recorded the new volume and subtracted the two recordings equaling the volume of the unknown. 4. We then calculate the density by dividing the mass by the volume. 5. We then remove the metal cylinder, dry it and repeat to get the other two densities. Then record the measurements and density for each trial and then average the densities.
Part 2: Calibration of a Buret
1. Get 4 small beakers, clean and dry them, then record the mass of each. 2. Get & Fill the buret past the zero mark.
3. Measure 10, 15,20,25 mL of water from the Buret separately into the four small beakers. 4. Measure and record the combined mass of the beaker and the water 5. Then we determined the actual volume of water by using the mass of water in the beaker, table densities, and the equation: volume equals mass over density. 6. We then calculated and recorded the absolute error and percent error for each volume.
Part 3: Calibration of Pipet
1. Obtained a beaker and measures its mass.
2. Draw a sample of water into the pipet above the calibration mark, then I quickly replaced the bulb on top on the pipet with my hand to prevent any water coming out past the calibration mark. 3. Then we emptied the water into the beaker
4. Measure the mass of the water and the beaker
5. Then we calculated the volume again by diving the mass by the density. 6. Repeat the same procedure two more times then calculate and record the absolute and percent error for each volume. Then we averaged the results.
Part 4: Density of an unknown liquid
1. Get a small beaker, measure the mass and pour approximately 10 mL of the unknown liquid and record the number of the unknown in the data table. 2. Then we transferred 5 mL of the unknown liquid into a dry beaker and measured that. 3. We then calculated the density of the unknown liquid. 4. Then we repeated it twice more and then calculated the average density.
Results and Calculations
PART 1: Density of an Unknown Solid
| Trial 1| Trial 2| Trial 3|
Mass| 53.74| 53.74| 53.74|
Initial Volume| 61| 69| 64|
Final Volume| 69| 75| 70|
Volume of Unknown| 8mL| 6mL| 6mL|
Density| 6.7175| 8.9566| 8.9566|
Average Density | 8.2102|
1. We calculated the Volume of the Unknown by subtracting the final volume by the initial volume. 2. We then calculated the Density by dividing the mass by the volume of the unknown. 3. Last we added all three densities and divided by 3 to get our Average Density.
PART 2: Calibration of a Buret
Buret Volume| Mass Of Beaker| Mass of Beaker & Water| Mass of Water| Volume of Water| Absolute Error| Percent Error| 10.00mL| 28.493| 39.587| 11.094| 11.122| 1.122| 11.22| 15.00mL| 28.493| 43.026| 13.533| 13.567| -1.433| -9.55| 20.00mL| 28.493| 45.799| 17.306| 17.349| -2.651| -13.255| 25.00nL| 28.493| 48.932| 20.439| 20.490| -4.51| -18.04| 1. First we calculated the Mass of the water by subtracting the mass of the beaker & water by the mass of the...