Basic Laboratory Operations and Identification of a compound
Discussion for Experiment 1 (Basic Laboratory Operations and Identification of a compound : Chemical Properties)
In the first experiment, the precision of instrument was studied by measuring the mass of water for several times. The result shows that the mass measurement of the balance is precise since the masses of water in six trials are somewhat close. The reason that the masses of water in each trial are not identical may come from the high sensitivity of the balance that keep fluctuating due to many factors, such as wind and vibration. Another possible reason is that the same beaker was used to measure the mass of water. There were several drops of the water cling to the beaker. This may increase the actual mass of water in each trial.
In the density part, the mass and density of zinc electrode was measured and calculated to determine the accuracy of the measurement. The result shows that the densities of zinc electrode in two trials are 6.2±1.6 g/cm3 and 9.4±3.8 g/cm3 (The average density is 7.8±3.8 g/cm3), which is not quite accurate, compared to the standard of solid zinc density1 (7.14 g/cm3)1. The random error may result from the reading of volume of water in graduated cylinder. The scale difference in 100 ml of graduated cylinder was 1 ml, which is difficult to determine the volume of water that is in between scales. The volume difference in two trials is 1 ml, which is very significant that may be the cause of the error. The reading of volume of water in graduated cylinder should include one or two decimal places in order to make the calculated result more accurate. Repeating more trials (averaging) could also prevent the random error.
In the liquid part, the density of water and ethanol were determined at room temperature to measure the accuracy of pipette measurement. The average density of water of two trials is 1.0±0.1 g/ml, which is very accurate, compared to the standard density of water at room temperature (approximately 1 g/ml)2. The
In the first experiment, the precision of instrument was studied by measuring the mass of water for several times. The result shows that the mass measurement of the balance is precise since the masses of water in six trials are somewhat close. The reason that the masses of water in each trial are not identical may come from the high sensitivity of the balance that keep fluctuating due to many factors, such as wind and vibration. Another possible reason is that the same beaker was used to measure the mass of water. There were several drops of the water cling to the beaker. This may increase the actual mass of water in each trial.
In the density part, the mass and density of zinc electrode was measured and calculated to determine the accuracy of the measurement. The result shows that the densities of zinc electrode in two trials are 6.2±1.6 g/cm3 and 9.4±3.8 g/cm3 (The average density is 7.8±3.8 g/cm3), which is not quite accurate, compared to the standard of solid zinc density1 (7.14 g/cm3)1. The random error may result from the reading of volume of water in graduated cylinder. The scale difference in 100 ml of graduated cylinder was 1 ml, which is difficult to determine the volume of water that is in between scales. The volume difference in two trials is 1 ml, which is very significant that may be the cause of the error. The reading of volume of water in graduated cylinder should include one or two decimal places in order to make the calculated result more accurate. Repeating more trials (averaging) could also prevent the random error.
In the liquid part, the density of water and ethanol were determined at room temperature to measure the accuracy of pipette measurement. The average density of water of two trials is 1.0±0.1 g/ml, which is very accurate, compared to the standard density of water at room temperature (approximately 1 g/ml)2. The