Unit 2 Assignment 2: Colourimetry

BTEC Level 3 Extended Diploma in Applied Science Assignment
grade achieved

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Cooling

Calorimetry is a process in which the measurement of transferred heat is taken. This measurement of
transferred heat is further used in coal industries such as coal-fired power stations. The calorimetry process is
vital in industry as it provides safety information which further allows engineers and scientists to make
informed decisions.

By following the calorimetry technique, the cooling graph of both stearic acid and paraffin wax can
be formed. Through these graphs, the melting points of both these substances can be sought out and their
gradients calculated using tangents. In addition to this, we can study both the cooling curves for paraffin wax
and stearic acid.

Apparatus and material:

 Analogue and digital thermometer
 100ml beakers (2x)
 Salt and ice
 Boiled water
 Stop clock
 Boiling tube rack
 Boiling tubes
 Water bath
 Paraffin wax
 Stearic acid

Calibration:

Before the investigation, the calibration of both analogue and digital thermometers had taken place.
This was so to see whether the analogue or digital thermometers were better suited for the practical.

It is vital to calibrate thermometers to find which are more reliable than others. This reliability would
greatly affect the results of the calorimetry investigation.

Method for calibration:


1. For the calibration, a beaker with both salt and ice was prepared.
2. An analogue thermometer was placed into the beaker with salt and ice.
a. This was done to bring the temperature below zero degrees.
b. This was also done for the digital thermometer.
3. In a separate beaker, boiled water was poured which was recorded to be eight-seven degrees.
a. The boiled water was attained using a kettle
4. The analogue thermometer which was left in the beaker with both salt and ice was then
transferred to the beaker with boiled water,
a. A stop clock was started immediately after the analogue thermometer was moved.
b. This was also done to the digital thermometer.
5. Once the thermometer read eighty-seven degrees, the stop clock’s time was stopped and
recorded.
a. The time to read the temperature from zero degrees to eighty-seven degrees of the
analogue and digital thermometers were compared.
6. This process was repeated twice

After the calibration had taken place, the time taken to read the temperature from zero degrees to
eighty-seven degrees for the analogue thermometer was seventeen seconds whilst the time for the digital
thermometer was nineteen seconds.




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, BTEC Level 3 Extended Diploma in Applied Science


As the time taken to read temperature was quicker for the analogue thermometer, it was used in the
calorimetry practical.

Method for calorimetry of stearic acid:

Apparatus and material:

 Analogue thermometer
 Boiling tube rack
 Boiling tube
 Stop clock
 Stearic acid

During the calorimetry practical, a change of state was witnessed for two substances, stearic acid and
paraffin wax.

1. The temperature of the water bath of 5g of stearic acid was recorded using an analogue thermometer.
a. This temperature was recorded to be 62oC.
b. The temperature of the water bath of 62oC was recorded to be the temperature at 0 time.
2. The boiling tube of stearic acid was then taken out of the water bath and into a test tube rack.
a. As soon as the stearic acid was transferred out of the water bath, the stop clock was started.
b. The analogue thermometer used was placed in the boiling tube so as to not measure the
temperature of the edges of the boiling tube but only the stearic acid.
3. The time displayed on the stop clock was recorded whenever the temperature of the stearic acid
dropped by 1oC.
a. This was recorded until the stearic acid in the boiling tube reached room temperature which
was recorded as 22oC.

After the practical had been carried out, the boiling tubes containing the substance was put back into
its water bath before removing the thermometer.

A cooling curve was then constructed of stearic acid after its change of state had been witnessed.

The method to find the melting point of 5g of paraffin wax follows the same steps as stearic acid, the
only change was of the substance within the boiling tube which was paraffin wax rather than stearic acid. In
addition, the temperature of the water bath of paraffin wax was 65 oC which was recorded as 0 time.




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