Techniques and Measurements
Background Information
There are several aspects of chemistry laboratory measurement all of which are centralized at data collection (Douglas et al., 2011). In chemistry, it is therefore, essential to have key knowledge on different laboratory measurement techniques. All the safety rules needs strict adherence, with measurements done precisely. Through international system of units (SI), different measurements are applicable to different objects. Furthermore, different common laboratory equipments are vital for measurements (Haynes et al., 2012). The laboratory units have both a number and a scale. The standard system is used to measure length, temperature, amount of substances and mass. All the quantitative measurements lack meaning without their associated units of measurements.
The Purpose of the Experiment
The purpose of this experiment is to determine the length of different objects, temperature of water, and the mass of diverse objects. Different principles such as the metric and Archimedes ideology will be essential for different measurements. Furthermore, the basis of this experiment was to establish molarity, number of moles and the relationship between molarity dilution and density of a resolution.
Procedure
- Length measurements
Different objects such as a metric ruler, key, DVD, spoon, and a fork were gathered. The ruler was used to measure the length of the different objects. The data recorded in Table 1 in centimeters, and millimeters respectively, after which, it was converted to meters.
- Temperature measurements
Water was collected in a 100ml glass beaker. The calibration mark on the thermometer was observed to determine the degree of uncertainty. The hot tap water was left to run for approximately 15 seconds, and the temperature measured using the thermometer. 100ml glass beaker was filled with approximately 75ml of hot tap water. The temperature was measured and recorded in Table 2. The beaker was placed in a hot wire gauze burner, and the water was allowed to heat to boiling point. The temperature was recorded after 1 minute and five minutes of boiling. The beaker was allowed to cool, then cold tap water as poured into it and the temperature recorded. A handful of ice cubes was added and the temperature recorded after 1 and five minutes. Each of the temperature measurements was converted to Kelvin (K) and Fahrenheit units of measurements.
- Mass measurements
Pen, 5 pennies, 3 quarters, 4 dimes and a key were collected and their weight estimated in grams. The weights of the objects were measured using a digital scale, and the data recorded in Table 3. Each of the actual masses was converted to kilograms.
- Liquid measurements solvent
A clean dry 25ml-graduated cylinder was weighed, then, 5 ml of water was added. Then the water was determined (calculated). Using isopropyl alcohol, this procedure was repeated to determine the density of water and the alcohol. The percent error was recorded in Table 4.
- a) Magnetic measurement method
On magnet, the mass was measured in grams. The length of the three dimensions of the magnet (height, width and length), were determined with a ruler. The attained data, was used to determine the magnet’s density and volume. By means of a string, the metal bolt’s length and diameter were measured (as recorded in Table 6). The attained data was used to calculate the volume and density of the bolt.
- b) Archimedes principle method
The magnet was placed into a graduated cylinder with water. The displaced water was collected and the weight was calculated. Then, the metal bolt was suspended in to the water. The mass of displaced water was then determined (as recorded in Table 7).
- Solute and concentration analysis
Eight grams of sugar was weighed, and using a white paper, the sugar was transferred to a volumetric flask. The molecular weight of the sugar was used to determine molarity, and density of the sugar. The mass of the sugar solution was recorded in Table 9. Using a volumetric flask, 2.5 ml of the sugar solution was pipette and used to perform serial dilutions of 3, 4.5, and 6.0 of the sugar solution. The molarity and densities of the diluted solutions were recorded in Table 9.
Results and Data
Table 1: Length measurements degree of uncertainty
| Object | Length (cm) | Length (mm) | Length (m) |
| Key | 3 | 30 | 0.3 |
| Spoon | 22 | 220 | 2.2 |
| Fork | 15 | 150 | 1.5 |
| DVD | 12 | 120 | 1.2 |
Table 2: Temperature measurements
| Water | Temperature (°C) | Temperature (°F) | Temperature (K) |
| Hot from tap water | 50.1 | 609.98 | 321.1 |
| Boiling | 99.9 | 703.22 | 372.9 |
| Boiling for 5 minutes | 100.6 | 7.4.48 | 373.6 |
| Cold from tap water | 7.1 | 536.18 | 280.1 |
| Ice Water -1 minute | 5.8 | 533.84 | 278.8 |
| Ice Water 5 minutes | 1.0 | 525.2 | 274 |
Table 3: Mass measurements
| Object | Estimated mass ( g) | Actual mass(g) | Actual mass (kg) |
| Pencil | 5.0 | 5.1 | 0.0051 |
| 3 pennies | 15 | 15.5 | 0.0155 |
| 3 Quarter | 18 | 18.75 | 0.01875 |
| 2Quarter,3 dimes | 19 | 19.21 | 0.01921 |
| 4dimes, 5 pennies | 24 | 24.58 | 0.02456 |
| 3 quarters, 1 dime, 5 pennies | 36 | 36.52 | 0.03652 |
| Key | 12 | 12.1 | 0.0121 |
| Key,1 Quarter, 4 pennies | 30 | 30.75 | 0.03075 |
Table 4: Liquid measurements
| Water | Measurements | Isopropyl alcohol | Measurements |
| Mass of empty 25 ml cylinder | 22.17g | Mass of empty 25 ml cylinder | 22.17g |
| Mass of beaker +5ml water | 27.12g | Mass of beaker +5ml isopropyl alcohol | 26.02g |
| Mass of water | 4.95g | Mass of alcohol | 3.85g |
| Density of water | 0.99g/ml | Density of alcohol | 0.77g/ml |
| Accepted density | 1g/ml | Accepted density | 0.786g/ml |
| Percentage error | 0.1 | Percentage error | 0.016 |
Table 5: Magnet measurement method
| Object | Measurements | |
| Magnet | Mass(g) | 2.5 |
| Length(cm) | 0.5 | |
| Width(cm) | 0.8 | |
| Height(cm) | 0.25 | |
| Density(g/cm3) | 38.31 | |
| Metal bolt | Mass(g) | 40 |
| Diameter(cm) | 1 | |
| Height(cm) | 2 | |
| Density(g/cm3) | 25.47 |
Table 7: Archimedes principle
| Magnet | Mass(g) | 2.5 |
| Initial volume of water(ml) | 100 | |
| Final volume(ml) | 100.65 | |
| Weight of displaced water (g) | 2.49 | |
| Density of the magnet | 38.31 | |
| Metal bolt | Mass (g) | 40 |
| Initial volume of water (ml) | 100 | |
| Final volume (ml) | 101.57 | |
| weight of displaced water | 39.97 | |
| Density of the metal bolt | 25.47 |
Table 8: Initial concentration
| Weight of sugar C12H22O11(g) | 8 |
| Molecular weight(g/mole) | 342.186 |
| Moles | 0.0234 |
| Morality (M) | 0.936 |
| Mass (g) | 320.286 |
| Density(g/ml) | 12.81 |
Table 9: Serial dilutions
| Dilution | Molarity | Density(g/ml) |
| 0 | 0.936 | 12.81 |
| 2.5 | 0.855 | 1.28 |
| 4.5 | 1.539 | 2.304 |
| 3 | 1.026 | 1.536 |
| 6 | 2.053 | 3.072 |
Molarity verses density chart
Figure 1: Molarity versus density chart
Answers to questions.
- A) The water in this experiment did not boil at 100 degrees Celsius because the tap water is not pure and might contain impurities. The boiling point of water is not different from the atmospheric pressure. Even so, the solvents’ (dissolved solvents) boiling point in the tap water raises the boiling point of the water. In short, when the pressure is equal to the atmospheric pressure, then, the boiling point of water is high.
(B) Percentage error for boiling point (102 degrees Celsius) = 0.02
Percentage error for boiling point (99.8 degrees Celsius) = 0.02
- C) Density is equivalent to mass/ volume
Mass =21.6g
Volume = (length x width x height) = 3.6 cm x 4.21 cm x 1.17 cm =17.73cm3
Density = 1.22g/ cm3
- D) Mass of gold (Au) = 26.15g
Theoretical density = 19.30g/ml
Volume of the gold = mass/density = 1.355ml or 1.355 cm3
- E) Because of surface tension forces, the weight of water displaced ≠ the weight of the object. This aspect is attributed to Archimedes principles, which relies on buoyancy, to determine the upward force of a submerged object. Based on Archimedes principle, the buoyancy force experienced by a submerged object is similar to the weight of displaced water (liquid).
- F) Compared to calculated volume, the determination of magnetic measurements through Archimedes principle are more accurate and lower. Archimedes principle is more accurate because when a solid of Volume (V) is immersed in a fluid, it experiences a buoyant force (F-B), which is equal to the weight of fluid displaced (Piazza, et al., 2012). On the other hand, most scales used in the laboratory are calibrated in units of mass and not the units of force. The reading on the scale is not the force in the string, but the tension divided by the gravitational force.
- G) Density of the colored material is mass/volume = 15g/cm3
This material is not gold because the density of gold is 19.30g/cm3. Gold has a higher density, much higher than the densities of several other metals.
- H) I will use the formula C1V1 = C2V2, where C = concentration,
V = volume
Therefore, 2.5ml of 1M HCL is needed, with 1000 ml of water.
- H) There was a direct relationship between Molarity and the densities of the dilution. Different dilutions of the sugar solution had varied densities due to differences in molarity, volume and sugar concentration levels.
References
Douglas, A. S., Donald, M. N., Holler, F. J., Crouch, S. R., & Chen, S. C. (2011). Introduction to Analytical Chemistry. Case bound.
Haynes, W. M., Lide, D. R., & Bruno, T. J. (Eds.). (2012). CRC Handbook of Chemistry and Physics 2012. CRC press.
Piazza, R., Buzzaccaro, S., Secchi, E., & Parola, A. (2012). What buoyancy really is. A generalized Archimedes’ principle for sedimentation and ultracentrifugation. Soft Matter, 8(27), 7112-7115.
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