The aim of this experiment was to evaluate a sample so as to determine its density. This was achieved by finding its mass and volume. The specific gravity of liquids was also determined where two liquids were used. For the purpose of determining the specific gravity of liquids, the experiment was done in pairs. Each partner worked on one liquid using the same procedure provided and then shared results at the end of the experiment.
Procedure
Density of Regularly Shaped Solids
Cubes: take a sample of a cube. Using a weighing scale, determine the mass (g) of the cube. Measure the length (l) of one side of the cube in (cm) using a meter rule. Calculate the volume in cm3, that is (v=l*l*l) and then the density of the cube by dividing the mass with the volume, D=m/v in g/cm3
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Rectangular solids: acquire a sample of a rectangular solid and weigh it to get its mass (g) using a weighing balance. Using a meter rule, determine the length, the width and the height of the rectangular solid in cm. Calculate the volume of the solid in cm3, that is (v=l*w*h).Calculate the density of the solid using the mass and volume values acquired in the experiment, i.e. (D =m/v in g/cm3)
Density of Solids by Displacement
First, get an irregular shaped solid and weigh it to get the mass (g) using the weighing scale. Half fill a 100ml measuring cylinder with water and record the volume at the lower meniscus as (V initial). Carefully immerse the solid into the water taking care not to splash the water or break the glass. Record the new volume of water in the measuring cylinder as (V final). Calculate the volume of the solid by subtracting the initial volume from the final volume, i.e. (V=V final-V initial) Note that 1.0ml=1.0cm3.Using the values of mass and volume from the experiment, calculate the density of the solid, (D=m/v in g/cm3). Determine what your unknown solid is likely made of from the table below.
| Material | Density (g/cm3) | Material | Density (g/cm3) |
| Aluminum | 2.7 | Nickel | 8.9 |
| Brass | 8.0 | Platinum | 21.4 |
| Copper | 8.9 | Silver | 10.5 |
| Gold | 19.3 | Stainless steel | 8.0 |
| Iron | 7.9 | Tin | 7.3 |
| Lead | 11.3 | Zinc | 7.1 |
Density of Specific Gravity of Liquids
For this experiment, use deionized water and 2-propanol. Get 20ml of each liquid. This experiment should be done with a partner. Each partner should follow the following procedure. Take the mass of a clean 50ml flask with a rubber cork and record. Transfer 10ml of the liquid into the flask using a pipette and pipette filler and put the cork back. Weigh the flask, cork, and the liquid and record the new mass. Calculate the mass of the liquid by getting the difference of the two obtained masses. Determine the density of the liquid using the mass and volume obtained. Transfer a second 10ml portion of the liquid into the weighed flask using the pipette and cork the flask. Determine the mass of the flask, cork and the liquid and record the results. Calculate the total mass of the liquid by getting the difference between the new mass and the initial mass. Calculate the density of the liquid for a volume of 20ml. Determine the average of these two densities and calculate the specific gravity of the liquid from the average density. Note that specific density is calculated by dividing the density of the sample liquid by the density of water. Go to the lab station and view the hydrometers. What is the specific gravity of the solution you analyzed using the hydrometer? Compare with your calculated value.
B: Density of Regularly Shaped Solids
| Cube ID, appearance | Mass (g) | Length of a side (cm) | Volume (cm3) | Density (g/cm3) |
| Wooden | 10.15 | 2.4 | 13.83 | 0.734 |
| Rectangular solid ID, Appearance | Mass (g) | Length (cm) | Width (cm) | Height (cm) | Volume (cm3) | Density (g/cm3) |
| Plastic | 50.44 | 10.1 | 2 | 10.1 | 204.02 | 0.2472 |
C: Density of Solids by Displacement
| 1 | Mass of the sample (g) | 27.036 | ||
| 2 | Volume of water alone (ml) | 30 | ||
| 3 | Volume of water plus sample (ml) | 40 | ||
| 4 | Volume of sample alone (ml) line3-line2 | 10 | ||
| 5 | Density of metal sample in g/ml or g/cm3 line1/line4 | 2.7036 | ||
| Identification | Unknown #: 14 | Likely material (best match of density value): Al | ||
D: Density of Specific Gravity of liquids
| Identification | DI Water | 2-propanol | |
| 1 | Mass of the flask plus stopper (g) | 48.25 | 48.45 |
| 2 | Mass of the flask, stopper, and 10.00 ml of sample (g) | 56.29 | 54.24 |
| 3 | Mass of the 1st 10.00 ml sample (line 2- line 1) | 8.04 | 5.78 |
| 4 | Density of the liquid (line 3 / 10.000 ml) | 0.804 | 0.578 |
| 5 | Mass after the 2nd 10.00 ml sample is added (g) | 63.72 | 60.55 |
| 6 | Mass of the 20.00 ml sample (line 5- line 1) | 15.47 | 12.09 |
| 7 | Density of the liquid (line 6 / 20.00 mL) | 0.7735 | 0.605 |
| 8 | Average of your 2 density measurements (line 4 + line 7) /2 | 0.7915 | 0.5925 |
| 9 | Average specific gravity (line 8 / 1.00 g/ml) | 0.791 | 0.592 |
| 10 | Read the specific gravity from the hydrometer | 1g/ml | 0.800g/ml |
| 11 | Compare your data value from that with the hydrometer. How close are they? If they are different, why? | 0.2 difference holds more | 0.300 difference holds more |
Results and Conclusion
The acquired density value of 2.7036g/ml for aluminum was a reasonable value for the material. The published value being 2.7g/ml, the accuracy of the experiment was 98%. Some of the sources of error may have been inaccurate reading of the volume from the graduated measuring cylinder and the other probable source of error could be that the material absorbed some of the water when it was immersed in the measuring cylinder.
Summary
The data used in this lab report was acquired through experiments done in a laboratory. The data may have some experimental errors. However, the results obtained are 98-99% accurate and the value attained is close to the published value.
