Calibrating Thermometers Assignment Sample

Introduction Of Calibrating Thermometers

The report aims to calibrate several types of thermometers (liquid thermometers and digital thermometers) to evaluate the “melting point” of ice and “stearic acid” to identify the “cooling point”. Further, it will evaluate and analyse the “rate of cooling” of substances and compare it using cooling curves.

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Calibrations of thermometers

Figure 1: Digital and liquid thermometers

(Source: Khattab et al., 2020)

The process of calibratingalcohol andmercury thermometers has been done using cold and hot water. In the beginning, a "250 cm3 beaker" has been filled with "crushed ice" along with tap water in a small amount (Khattab et al., 2020). The mixture has been stirred with a glass rod and allowed to settle, approximately for 2 to 3 minutes. Next, the thermometer has been inserted into a beaker, and the readings have been taken each minute for about eleven minutes. These results have been then recorded on a suitable table. The next step involved calibrating the thermometers using hot water. The beaker has been filled with water and heated until it reached boiling point, indicating a temperature of 100°C (Wijaya et al., 2020). The thermometer has been placed into the boiling water, and then the readings have been taken every minute for about 11 minutes, which has been then recorded on a suitable table.

Figure 2: Thermometer calibration

(Wang et al., 2021)

Preparation of cooling curve for stearic acid

Aim

The report aims to do the determination of changes that occur physically and also the temperature changes, and further study the cooling curves by using both stearic acid and paraffin wax.

Introduction

The experiment aims to utilize the "calorimeter method" to determine the "cooling curve" of a solid substance. The “calorimeter” is a vessel, typically a "polystyrene cup" or a "glass beaker", which can be used in a conjunction with thermometer for recording changes in temperature during the reaction that involves exchange of heat with the surrounding environment (Wang et al., 2021). "Calorimeters" are commonly utilized to monitor exothermic or endothermic reactions, and phase changes such as melting or freezing, and to determine "specific heat capacity". This method is a process to measure the amount of transferred heat. There exist two major thermometers types, which have been utilized in calorimetry: "liquid-filled thermometers", which may use alcohol or mercury, and "electronic thermometers" such as thermistors, rotary thermometers,thermocouples, resistance thermometers, and infrared thermometers (Fan et al., 2022). It has been found that each type of this thermometer operates according to its own principle and is suited to specific applications.

Equipment

• Digital thermometer
• Beaker
• Stearic aid
• Clamp and retort stand
• Stop clock
• Bunsen burner
• Gauze
• Tripod
• Boiling tube

Safety measures

Proper safety measures have been followed during the experiment. Precautions have been taken for the use of the chemical stearic acid as it can cause irritation in the skin and eye. Further, glassware and bunsen burner have been used in a very careful manner and all the instructions of the experiment have been followed.

Method

Figure 3: Experiment method

(Source: Du et al., 2021)

Before starting the experiment, the equipment provided has been thoroughly cleaned and washed as well as calibrated. Next, ten grams of "stearic acid" has been placed in a boiling tube, which has been subsequently placed in a beaker of boiled water (Du et al., 2021). Followed by that, the digital thermometer has been incorporated into boiling tube for monitoring the drop in temperature as the “stearic acid” cooled down. Thereafter, the "melting point" of the stearic acid has been observed as it started heating up and liquefying. The highest temperature of the liquid stearic acid has been noted before the boiling tube has been removed from the boiling water and allowed to cool down (Du et al., 2022). Next, the temperature of “liquid stearic acid” has been recorded at "1-minute intervals" for 20 minutes until the liquid started to solidify. Further, a "cooling curve graph" of the stearic acid has been plotted, with "temperature" on the "y-axis" and "time" on the "x-axis". Followed by that,a “curve of best fit” has been drawn, and the "cooling rate" has been calculated from the gradient of the curve. Finally, generated results have been analyzed.

Results

Table 1: Temperature of stearic acid

(Source: Provided)

The above table represents the temperature of stearic acid recorded at an interval of 1 minute for 20 minutes. Digital thermometers have been used to measure the temperature drop. The table shows that the initial temperature has been 80 °C.

The above graph depicts the cooling curve of the “static acid” using a digital thermometer. In this graph, the temperatures have been plotted on the “y-axis” and time has been plotted on the “x-axis”.

Calculations

For calculating the "rate of cooling", the experiment data of temperature and time has been utilized.

Formula: "Rate of cooling" = "(T1 - T2)" / (“t1 - t2”)

Where "T1" is the "initial temperature", "T2" is the "final temperature", "t1" is the "initial time", and "t2" is the "final time".

Here, "initial temperature' has been "80°C" and "final temperature" is "29°C", and the "time interval" for the cooling process is "20 minutes", the formula has been utilized to calculate the “rate of cooling” as follows:

"Rate of cooling" = (80 - 29) / (0 - 20) = -2.55 °C/min

Therefore, the average "rate of cooling" for this experiment is approximately -2.55 °C/min, which means that the temperature decreased by about 2.55 degrees Celsius every minute during the cooling process.

Here, the drop in temperature has been divided into two segments to understand the “rate of cooling” more precisely. Thefirst segment is from time 0 to time 5, where temperature has decreased from 80°C to 60°C. Next, thesecond segment is from time 6 to time 20, where the temperature decreases from 59°C to 29°C.

The “rate of cooling” has been calculated for each segment separatelyusing the same formula:

For the first segment:

T1 = 80°C, T2 = 60°C, t1 = 0 min, t2 = 5 min

“Rate of cooling” in the first segment = (80 - 60) / (0 - 5) = -4 °C/min

Thus,the “rate of cooling” in the first segment is approximately -4 °C/min, which means that the temperature decreased by about 4 degrees Celsius every minute during the first segment of the cooling process.

For the second segment:

T1 = 59°C, T2 = 29°C, t1 = 6 min, t2 = 20 min

“Rate of cooling” in the second segment = (59 - 29) / (6 - 20) = -2 °C/min

Therefore, the “rate of cooling” in the second segment is approximately -2 °C/min, meaning that the temperature decreased by about 2 degrees Celsius every minute during the second segment of the cooling process.

Investigation of paraffin Wax by Calorimetry

Paraffin wax has been commonly used in denoting the group of different alkanes and hydrocarbons, having the general formula C_nH_2n+2, where "n" helps in denoting the number which is greater than the value 20 (Elaremet al. 2022). They can take different solids and liquids forms. The calorific value of paraffin wax is42 MJ/kg. Studies have shown that the increase in the energy and the application of certain phase-changing methods and materials could be new phenomena for controlling the temperature, and the storage of the energy which helps in managing the investigation areas (Sathishkumaret al.2023). Certain phase change materials help in fixing the melting point and help in regulating the flexibility of the nontoxic and non-corrosive high latent heat of the paraffin Wax. Further for improving the thermal conductivity of the paraffin wax, nao-particles, and diamond has been used as the additive for the microencapsulation of the paraffin wax which helps to coat the "Gelatin-Gum Arabic" (Sadrameliet al.2019). By doing the calorimetric test of the experiment, it was investigated that the measurement and the efficiency of the microcapsules after doing the heat test and washing it with toluene showed different and positive results for the experiment(Elarem et al. 2022). The thermal properties were measured and calculated by the calorimetric analysis using "Differential scanning calorimetry" "(DSC)" tests.

Further investigations were done and analyses were made and recorded for the experiments. The studies by (Elaremet al.2022) showed that different samples were taken for doing five phases of changing and determining the properties of the thermal methods, where "100 paraffin wax", "99.5 paraffin wax" also "0.5 MWCNT", "99.5 paraffin wax" + "0.5 BN", "99 paraffin wax" + "0.5 MWCT" + "0.5 BN" and "98 paraffin wax" + "1 MWCNT" + "1 BN" "mass percentage compositions" were taken under considerations(Elarem et al. 2022). The size of the particles was further determined by the usage of "TEM"(Elarem et al. 2022). Different scanning methods opted for the measurement of the calorimetry (DSC) and the analysis of the thermal conductivity of the physical and thermal properties of the conducting test methods. Further, the results revealed that the hybrid composition of the powdered nano-meters has increased from "0.18" to "0.31" Wm⁻¹K⁻¹

Thus the investigations were done based on different experimental analyses and were found to give several results of the experiment depending on the analysis and the experimental observations that were made from the different results obtained in the experiments(Elaremet al. 2022). Further, the tests were also done at the right temperature of the melted paraffin wax. The wax needs to be poured into the plastic container which has been greased and then the wax forms thin skin, after which the temperature has been tested and checked for making it ready and experimentally true.

Discussion

“Stearic acid” is a "fatty acid", commonly obtained in food products like margarine and butter. This experiment required precise temperature measurements at each step, particularly when the boiling tube has been placed in a beaker of boiled water, which was freshly boiled. It has been evident that careful attention has been needed during the temperature check as the thermometer did not always display 100 °C (Voronin et al., 2022). Further, great care has been taken to prevent spills of hot water when inserting the "digital thermometer" into the boiling tube, as exposure to hot water could cause skin burns.

The experiment showed that at the start of the “cooling process” for stearic acid, the “rate of cooling” has been“4 °C/min”. However, at the end of the process, it decreased to “2 °C/min”. The temperature at which“stearic acid” has been measured and recorded using a “digital thermometer” and the “resulting graph” has indicated a change in the “cooling rate” after the “first gradient”, where the curve bends due to the melting point. This explains the drop in temperature as the “stearic acid” starts to pipe down (Dai et al., 2022). Further, the "flat section" in the graph has represented the time “stearic acid”has taken to transform from a "liquid to solid' state, as evidenced by the slight drop in the curve. After this point, the stearic acid remained solid and the curve remained constant.

The aim of the report has been to construct a "cooling curve" for "stearic acid" using several thermometers, "digital thermometer", being one of them. The experiment has been conducted with great care as well as caution to achieve high reliability and accuracy in constructing the cooling graph. For verifying the reliability of the experiment results, the results have been compared to the calculated "rate of cooling" for "stearic acid" with published data. According to the punished articles, the "melting point" of stearic acid is 66 °C, and the melting point observed in the experiment has been around "66-69 °C", indicating that the experiment has been successful (Kar et al., 2022).

However, there has been a discrepancy between the calculated “rate of cooling” for the experiment and the values provided in the “student book”. The actual "rate of cooling" for the “first gradient” has been stated to be "6.32 °C/min", whereas in this experiment the calculated value was "4 °C/min". Similarly, the actual value for the “second gradient” has been shown to be "2.63 °C/min", but in this experiment, the calculated gradient was "2 °C/min" based on the graph, derived from using the digital thermometer (Kar et al., 2022). The results suggest that the utilization of digital thermometers is not reliable in the case of measuring cooling temperature.

It has been found that thespeed at which substances cooldown is closely linked to their intermolecular forces and their state. The reason behind this is thatis because the “existence of molecular liquids”, solids and gases depends on a delicate equilibrium between the "intermolecular forces" that “hold them together” as well as the “kinetic energy” of the molecules, which pushes the substances apart (Du et al., 2021). Further, theprocess of heating and coolingsolids andliquids also plays a role in determining their "physical state". It has been seen that bothsolids andliquids possess distinct properties and behaviours in this regard.

It has been also seen that liquidsmaintain a fixed volume regardless of the shape of the container, whereas solids do not adapt well to the shape of their container. Further, liquids are generally less dense compared to solids, which tend to be denser as well as less compatible. In addition, the "intermolecular forces" in liquids are strong enough to keep individual atoms united, while solids rely on intermolecular forces to keep their molecules bound together (Liu et al., 2022). Moreover, liquids lack the ability for attractive forces to hold molecules together, whereas solids rely on these forces to establish a rigid structure. It has been seen that diffusion happens at a relatively slow pace in liquids, while it occurs even more slowly in solids.

Hence it can be infered that “intermolecular forces” can be summarized as the combined effect of attractive and repulsive forces among molecules. The physical state of a substance is primarily determined bythe "kinetic energy" of its atoms andthe "strength" of the "attractive forces" (Fabbrizzi, 2022). In addition, "intermolecular forces" impact various properties such aspressure, boiling and melting points, as well as viscosity. It has been seen that strongintermolecular forces require higher temperatures to overcome the attractive forces between molecules, which implies that a significant amount of additional heat energy is necessary to convert a solid into a liquid, and even more, energy is needed to transform a liquid into a gas. Moreover, when the temperature is raised, the particles gain kinetic energy, causing a weakening of the attractive forces and resulting in the melting of solids into liquids (Fabbrizzi, 2022). In contrast, when the temperature decreases, the particles lose kinetic energy, leading to a strengthening of the attractive forces, which causes liquids to freeze and eventually become solids.

Conclusion

The theory of intermolecular forces has beenimplemented in the experiment by subjecting the solid substance to heat energy, causing it to transform from a solid to a liquid state. Subsequently, the substance has been allowed to cool down by reducing the temperature. The rate at which the stearic acid cooled has been observed to be influenced by the speed at which the temperature decreased, enabling the accurate determination of the gradient.

References

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