BTEC Applied Science unit 2, assignment B: Using calorimetry to study cooling curves
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Course
Unit 2
Institution
PEARSON (PEARSON)
I received a Distinction grade for this piece of coursework.
Please be aware before purchase that this was carried out during the academic year affected by COVID, thus does not include any investigations on stearic acid. Everything else, including graph analysis, methodology and relevant referenci...
Calorimetry is a scientific technique which uses a calorimeter to measure the amount of thermal
energy gained or released from the surroundings during a chemical reaction. It is possible to identify
whether a reaction is endothermic or exothermic by calculating the difference in heat 1. Careful
observations must be conducted, alongside accurate temperature note-taking to ensure a reliable
conclusion. There are various applications of this science investigation, disregarding the thermal
characterisation of different drug molecules, such as paraffin wax. Calorimetry can be used to
measure the calories present in food, controlling human metabolic rates and, as a result, regulating
functions such as body temperature2.
A container known as a ‘calorimeter’ is used to measure the heat transferred during a chemical
reaction. An ideal calorimeter should be constructed from metal, and contain good thermal
conductivity, such as a container composed of copper. A beaker would suffice; however, a
polystyrene cup is preferrable as it’s an exceptional thermal insulator, which better prevents heat
from being lost through the sides of the cup 3. Within this investigation, a glass beaker is used as the
calorimeter. Its transparency allows for direct monitoring of different chemical reactions within the
beaker. More efficient alternatives were not available at the conducted time of this experiment.
Within this experiment of calorimetry, the calibration of two different thermometers were
conducted. After deciding on the chosen thermometer, the cooling curves of ice in hot water and
paraffin wax were observed. The molecular compound, paraffin wax, is a colourless solid which
consists of hydrocarbons containing 30-40 carbon atoms. The melting points of paraffin waxes are in
the range of 40-60°C with boiling points of up to 37°C. Its chemical formula is CnH2n+24.
The following equipment were used in the experiments:
• Heating equipment (tripod, gauze mat, bunsen burner)
• Clamp stand
• Stop watch
• Digital thermometer
• 20g of paraffin wax
• Boiling tube
• Glass beaker
• 35g and 45g of ice (for separate practical’s)
• Weight balance
• 150ml of water
1 Calorimetry [Internet]. 2020 [cited 2021 May 3]. Available from: https://chem.libretexts.org/@go/page/1894
2
Calorimetry [Internet]. 2020 [cited 2021 May 3]. Available from: https://chem.libretexts.org/@go/page/1894
3 Guru. Ultimate Guide to the Best Calorimeters for 2020-2021 [Internet]. Nerd Techy. 2021 [cited 3 May 2021]. Available from:
https://nerdtechy.com/best-calorimeters
4 John P. Investigation of the Functionality of White Soft Paraffin with Regards to Ointments - White Rose eTheses Online
[Internet]. White Rose eTheses Online. 2017 [cited 3 May 2021]. Available from: http://etheses.whiterose.ac.uk/19302/
, Health and Safety
After repeated trials of the different components of this experiment, it is essential to construct a risk
assessment before carrying out this scientific investigation. This allows the experimenter to be more
aware of the risks involved, which will be detailed in this section. Since solutions and solids will be
heated to their maximum boiling point, this creates the danger of self-injury if the subject makes
naked contact with the substance. In addition, the use of glass boiling tubes and potentially a glass
thermometer develops the risk of shattering the glass and consequently, causing cutting injuries to
people nearby the incident. Therefore, a high sense of maturity alongside the wearing of protective
clothing must be ensured, to prevent this danger from occurring.
The use of paraffin wax is associated with a number of potential risks to remain mindful of. Whilst
using this substance, protective eye wear should be worn to avoid irritation of the eyes. Since
paraffin wax is highly flammable, it is vital to keep it away from a naked flame. If the experimenter
has very sensitive skin, paraffin wax is likely to cause heat rash. This results in small red bumps
appearing on the skin that can be itchy and uncomfortable5. If this side effect is experienced by the
experimenter, ensure to quickly inform the supervisor and act on any given advice; likely being to
run cold water down the infected spot and the temporary dismissal from the experiment.
The equipment used within this investigation consists of a Bunsen burner. This will be used within
every part of the experiment (a, b and c). However, its use correlates multiple risks to be mindful of.
They burn at a high temperature and produce an open flame. Consequently, there is potential for a
fire hazard to occur. If the experimenter has long hair or dangling jewellery/loose clothing, they
must be covered up. In case of a fire, activate the nearest fire alarm and notify all nearby lab
personnel to evacuate the building.
Part A - Calibration of a thermometer
To ensure that findings of this experiment were as accurate as possible, the initial calibration and
validity testing of two different thermometer types were conducted. A liquid thermometer
composed of glass and a digital thermometer were tested against predetermined temperatures of
boiling and iced water. The findings from both thermometers in the two different conditions were
compared to the known temperatures, leading to the decision of the thermometer to be used in the
other components of the investigation. Since a thermometer’s accuracy can fluctuate over time, its
necessary to calibrate it to ensure accurate readings. Consequently, this will lead to higher
confidence regarding the validity of any findings drawn upon the calibrated equipment as a result.
Regarding the pre-identified temperatures of the boiling and iced water, they were fixed and
determined before the calibration process of the two thermometers. The maximum temperature of
boiling water is 100°C, the known value of iced water is 0°C. These values were compared against
the measurements of the digital and liquid thermometer.
5 Wilson D. Paraffin Wax: Uses, Benefits, Risks, How to, and More [Internet]. Healthline. 2019 [cited 4 May 2021]. Available
from: https://www.healthline.com/health/paraffin-wax#what-to-expect
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