Density and Specific Gravity

Note on this virtual Lab Experiment Read the introductory principle procedure and experimental materials outlined below and understand as to how this virtual experiment would be conducted under real lab condition to generate the theoretical data supplied in Tables below. After clearly understanding the procedure and the formula for the calculations enter calculated values in the blank columns and write brief discussions as per the guideline and Submit it back in the Drop Box. Introduction Density Density is a physical property of solids and fluids that can be defined as the mass (m) or quantity of a substance contained in one unit of its volume (v). The density of water is 1.0 g/ml (1g/cm3); in other words 10ml has a mass of 10g. Specific Gravity Specific gravity of a body is that number which denotes the ratio of the mass of a body and the mass of equal volume water. Specific gravity = Mass of solid or liquid Mass of an equal volume of water Water is used as the standard because the density of water does not vary by more than 1/2 of a percent over the temperature range of zero to 30-degree Celsius. The density and specific gravity of any substance are numerically the same when the density is expressed in g/ml. When density is expressed in g/ml (g/cm3) specific gravity can be calculated by dividing the density value by 1 g/ml (1g/cm3) thus making it unit-less. Example for copper: density is 8.5 g/ml (g/cm3); specific gravity is 8.5. Standard specific gravities (densities) values of some materials are shown below: Water1.0 (1g/cm3)Aluminum 2.7 (2.7g/cm3) Copper 8.5 (8.5g/cm3) Steel7.8 (7.8g/cm3) The main objective of this experiment is to determine the densities and specific gravities of different materials and compare them with their standard values. Materials and Procedure Equipment Experimental Procedure Density of water Assignment The theoretical data generated for mass and volume of water are already given in Table 1. From these data calculate the density and % error values in the blank last column: % Error = */Standard value – observed mean/ x 100 Standard value *absolute difference (no negative sign) Density of pieces of metal (copper) Assignment The theoretical data generated following the procedure outlined above are given in Table 2. From these data calculate the density and % error values and enter in the last column blank spaces. Density of metal rounds (steel) Assignment The theoretical data generated following the above outlined procedure are given Table 3. From the given data calculate and enter the density for each replication the mean density value and the % error of the experiment using the given formulae. DATA SHEET Table 1. Density of water Replicate Mass of water (g) Volume of water (ml) Density (mass/volume) (g/ml) #1 80 84 #2 90 92 #3 100 103 Mean (average) % Error Table 2. Density of pieces of metal Replicate Mass (g) Volume (ml) Density Mass/volume (g/ml) Initial volume of water (V1) Final volume of water (V2) Actual volume of metal pieces (V2 – V1) #1 60 50 57 7 #2 70 50 58 8 #3 80 50 59 9 Mean (average) % Error Table 3. Density of round metal (steel) Replicate Mass of metal (g) Volume of metal (ml) Density mass/volume (g/ml) #1 70 9.5 #2 95 13.5 #3 120 16.0 Mean (average) % Error Discussion In the space provided below briefly discuss the results of each of your experiments by indicating the mean and percent error values. Also indicate the level of precision of the experiment by comparing the measurement results in the different replications as well as the level of accuracy of the experiment by comparing the means with their respective standard values. Try to give explanation for the level of error obtained by indicating possible sources of error if high % error (>10%) is observed. ________________________________________________________________________ ________________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ _____________________________ ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Beakers Graduated cylinders Analytical Balance Metal pieces (small) Metal roundsOverflow-cup with nozzle A 100ml graduate cylinder is filled with water more than half and read the exact volume in ml is read to one decimal place and record in Table 1 under the column designated volume of water (ml) Rep #1 third column. A 150ml beaker is tared (zero) on analytical balance. The volume of water in the cylinder is transferred quantitatively into the beaker; mass in grams of water in the beaker is measured and data record under mass of water (g) in the second column Rep #1 The same procedure is repeated for Rep #2 and #3 the mass and volume data recorded in the appropriate columns. The density of water (d) is calculated by dividing the mass (m) in grams of water to the volume (v) of water in ml. The mean density values are calculated by adding the three replications and dividing by 3. The error % as compared to the standard density of water which is 1g/ml is calculated using the following formula. Some metal pieces (copper) provided are weighed on a balance (about 60g) and the exact weight in gram recorded in Table 2 under mass (g) in column 2 Rep #1. A 100-ml cylinder is filled to about 50 ml of water and exact volume in ml is recorded under the V1 column Rep #1. The weighed metal pieces are immersed into the water in the cylinder. The new volume of water in ml is recorded under the V2 column in the data Table which is the volume after immersing the metal pieces. The change in volume of water (V2 – V1) is calculated and recorded (This is the actual volume in ml of the metal pieces). This procedure is repeated in the same manner to complete Rep #2 and #3. Density of metal pieces is calculated by dividing mass of metal by change in volume (g/ml) The mean density values are calculated by adding the three replications and dividing by 3. The error % as compared to the standard density of copper which is 8.5g/ml is calculated using the formula given under density of water measurement. The mass in gram of three metal round (steel) provided is measured one at a time and data entered in Table 3 under column 2 Replications #1 #2 #3 respectively. Overflow-cup with a drain-nozzle is placed on a bench above the water sink and filled with water until excess water flows out through the nozzle and levels off. After the excess water stops dripping out of the overflow-cup an empty beaker is held under the nozzle with one hand and the metal round of which mass entered in Rep #1 is gently dropped in the water with the other hand; the metal will displace a fraction of the water and water flows out through the nozzle into the beaker. The content of the beaker is then poured into a small graduated cylinder and the volume is measured in ml and data recorded under volume of metal column. The experiment described for Rep #1 is repeated in the same manner for metal rounds 2 and 3 and data entered in Row 2 and 3 in the appropriate columns. The density (g/ml) of the metal is calculated for each replication by dividing the mass of metal round (g) by the volume of metal (ml) and results entered in the last column. The mean density values are calculated by adding the three replications and dividing by 3. The error % as compared to the standard density of steel which is 7.8g/ml is calculated using the formula given under density of water measurement. 1. Density of water 2. Density of metal pieces 3. Density of metal rounds 1. Density of water 2. Density of metal pieces 3. Density of metal rounds ‘