Essay
BTEC APPLIED SCIENCE UNIT 2 ASSIGNMENT A
- Institution
- PEARSON (PEARSON)
distinction level, sentences that are in red show the criteria that are met.
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COOLING CURVES OF STEARIC ACID AND PARAFFIN WAXINTRODUCTION
The cooling curve measures how quickly a substance falls in temperature with time. This is a
way of calculating how pure a substance is. This is calculated by plotting and analyzing the
shape of the graph which precisely shows the melting and cooling point of the substances.
AIMS
The aim of this practice is to determine the cooling curves of various substances, in this
practical paraffin wax and stearic acid. After collecting the data, this data has allowed for
calculations to draw conclusions. The data obtained allowed for analysis and comparison
between the two substances. In order for the results to be concordant, calibration of the
thermometer was done. This practical indicates how pure substances e.g. water are used on
a daily basis. This is due to the fact that there are oceans that are contaminated by oil
spillages therefore in this time period, there is pollution that could harm people and living
habits in the environment. The method to show how pure the substances are is to calculate
them through a cooling curve.
CHOOSING A THERMOMETER
In the experiment, the thermometer is calibrated to 0°C by cooling it with ice water in a
beaker. This is to show the initial calculations of the temperature of both the substances
(stearic acid and paraffin wax) to view the differences between that and the final
calculations.
CALIBRATION TABLE
TESTS BEFORE CALIBRATION
1 100°C
2 100°C
Before calibration, the temperature is stationary (100°C), to make it more accurate the
thermometer is standardized (calibrated) to 0°C. This is to make sure the reading is much
more accurate and easy to distinguish without further confusion when doing the calculations
of Stearic acid and Paraffin wax. Below is what’s read after calibrating the temperature for
both substances.
TESTS DURING CALIBRATION
1 0°C
2 0°C
If I were to use a digital thermometer, it would be calibrated by accessing the calibration
mode.
, THE MAIN EXPERIMENT
Equipment that is used are:
Beaker: used to calibrate thermometer by cooling it with ice water
Two thermometers: to calculate the temperatures of both the substances
Water bath: calculate the initial temperature of both the substances
Boiling tube containing stearic acid
Boiling tube containing paraffin wax
Stopclock: calculate how the temperature changes as it is cooled down
Test tube rack: hold down the boiling tubes
PROCEDURE/METHOD
Before starting the method, make sure to rinse the equipment and dry them carefully so that
excess materials are removed from the equipment.
Place two boiling tubes containing stearic acid and paraffin into a beaker of boiling
water and wait until it starts to completely melt.
Place a thermometer on each of the boiling tubes, make sure not to adjust the
thermometer or move so that you are able to read the temperature without any
hassle.
Record the initial temperature.
Remove the boiling tube from the water bath and place it into the test tube rack. (To
be weary of not moving the boiling tube in the rack, make sure to place tissues under
it to be held in position).
Start the stopwatch every 30 seconds quickly before it cools down.
Record the temperature.
Repeat 5 and 6 in a necessary amount of time (20 times) to increase the level of
accuracy.
Independent variable (deliberately change): Time.
Dependent variable (what you measure): Temperature.
Controlled (what you keep the same): Thermometer, boiling tube, mass of the substances
[2.0g]
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