This is an in depth assignment discussing how to correctly obtain data using different equipment to construct cooling curves, determine the
rate of cooling of substances using cooling curves, and analysing the rate of cooling of substances from your data using cooling curves to draw valid conclus...
Pearson level 3 BTEC national diploma in forensic and criminal investigation
Unit 2b assignment 2
Introduction:
In this experiment, we examined cooling curves and what happens to substances when
they are heated and cooled, we used paraffin wax and stearic acid. Stearic acid is a
compound of C17H35CO2H and is used in many personal care products such as moisturiser
and sunscreen, its melting point is 69.3° because of its high molecular weight. On the
other hand, paraffin wax is a mixture of hydrocarbon molecules, which has a softer
texture to stearic acid and is colourless, it is used candles and cosmetics. Paraffin wax
has a melting point of 50-57°.
Part 1 (calibration of the thermometers)
Digital thermometer Test 1 Test 2 Test 3 Average
Boiling water 100°C 100.3°C 100.4°C 100.35°C
Ice water 1.2°C 1.3°C 0.8°C 1.25°C
Liquid thermometer Test 1 Test 2 Test 3 Average
Boiling water 102°C 104°C 104°C 104°C
Ice water 1°C 1°C 0°C 0.3°C
To start with, we gathered all the equipment we needed for the calibration of the
thermometers, we got a beaker and filled it with ice and then filled the rest of the beaker
with some distilled water, we then held the digital thermometer in the beaker, making
sure not to let the thermometer touch the sides or the bottom of the beaker because
that could affect the reading on the thermometer. We took the reading on the
thermometer ever minute and wrote it down in the table. Then we gathered a beaker
and filled it with distilled water, we placed it on a gauze, on top of a tripod with a Busen
burner underneath it, boiling the water in the beaker. We waited until the water in the
beaker was boiling and held the digital thermometer in the beaker, taking a reading from
the thermometer every minute and wrote it down in the table. We repeated this again
with the liquid thermometer and wrote down the results into the table.
Part 2 (stearic acid)
Risk assessment:
Risks of the experiment Safety precautions
Boiling water (could burn or scold skin). Make sure to take extra care when
handling the kettle and clean up any
slippages.
Beaker/test tube (it could be smashed If any glass is smashed make sure to tell
and could cut someone's hand). a teacher and clean it all up.
Method:
The first substance we heated up was stearic acid. We gathered our equipment, and fill
up the beaker with boiling water, then we put a clamp around the test tube with the
stearic acid, and put it in the beaker containing the boiling water, making sure to not let
it touch the bottom of the beaker because the bottom of the beaker will be a different
, temperature to the boiling water, we put the thermometer in the test tube making sure
the bottom of it was not touching the bottom of the beaker because it will of been a
different temperature and effected the reads we got off of the thermometer, we then
waited until the boiling water had melted the stearic acid completely, and took it out of
the beaker and rested the test tube on a stand. We then read the thermometer after one
minute and wrote it down in the table below.
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