BTEC Applied Science Level 3 National Extended Diploma Unit 2: Practical Scientific
Procedures and Techniques
Learning Aim B: Undertaking calorimetry to study cooling curves
By Zohal Nadeem
Keeping up the standards
Investigating the cooling curve of stearic acid
INTRODUCTION:
I am a newly appointed technical assistant at Chemcalequip and as part of the induction period, I must
demonstrate skills that I have learnt in a range of practical procedures and techniques. This means
that, I need to show how to use a calorimeter and associated equipment to produce enough data to
generate accurate analysis, evaluation and determination for the rate of cooling of substances.
A cooling curve represents the change in state of substances usually from a liquid to a solid or a gas to
a solid. In this experiment, the cooling curve of stearic acid is shown in a line graph so we can
observe the melting point and freezing point. Gas molecules are separated further apart from one
another and can move around freely whereas liquid molecules are kept closer together and are free to
flow easily around each other depending on the container shape. Finally, the solid state are molecules
that are held in an arranged, regular pattern held firmly together and can only vibrate and cannot be
compressed or poured. Kinetic theory states that as temperature increases, the speed of gas particles
increases. This suggests that thermal expansion takes place due to temperature change.
Also, the stearic acid molecules have hydrogen bonds and hydrogen bonds are known as
intermolecular forces of attraction. The solid stearic acid has permanent molecule bonds and in the
liquid state, stearic acid molecules can slide over each other because the bonds are breaking and
forming.
Stearic acid is a saturated fatty acid mainly made by the hydrolysis of animal, vegetable oils and fats.
Stearic acid has many applications for human use. For example, stearic acid is used in personal care
products such as sunscreen, lotions and moisturisers, cosmetics and lubricants. Therefore, stearic acid
is seen as effective and consumed by a large population.
In this report, I will be constructing an experiment for the cooling curve of stearic acid. The aim of
this experiment is to observe the changes of state, analyse the temperature change and the different
rates of cooling curve for stearic acid.
RISK ASSESSMENT:
Before, during and after the experiment, it is important to carry out health and safety measures to
prevent injuries and ensure a safe environment is obtained. The use of lab gear must be followed
which involves wearing safety goggles, making sure hair is tied up and wearing lab coats. In addition,
the thermometer must not be removed from the solid stearic acid because it will break.
The use of glassware creates the risks of cutting and bleeding. So, we had to wear safety goggles and
handle glassware carefully. The area must be cleared immediately and a teacher must be present for
assistance if there was broken glassware. Another hazard is boiling water, so the risk of burns could
occur. To prevent burns, we had to wear safety goggles and gloves. In addition, stearic acid is an
irritant so we had to make sure the room was properly ventilated so the windows were open and we
, wore safety goggles to prevent breathing difficulties such as asthma attacks. Also, the kettle contained
boiling water so we had to handle the boiling water carefully to prevent spillages and burns.
METHOD:
Equipment/Apparatus:
Beaker (250 ml^3)
Tripod
Gauze
Heat resistant mat
Bunsen burner
Boiling tube
Alcohol thermometer
Stopwatch
Tongs
Test tube rack
Method for cooling curve of stearic acid experiment:
The method below was extracted from the Pearson BTEC National Applied Science Book, Unit 2:
Page 114 and Page 115
1. Calibrate the alcohol thermometer using ice water
2. Obtain a suitable quantity of stearic acid and place into a boiling tube
3. Place the boiling tube into a beaker of freshly boiled water
4. Place a thermometer into the boiling tube (in preparation to record the drop in temperature as
the acid cools)
5. As the stearic acid heats up, it will begin to melt
6. Record the highest temperature of the now liquid stearic acid
7. Remove the boiling tube from the beaker of hot water using tongs and allow to cool in a tube
rack
8. Record the temperature over a period at set intervals as the acid cools and for a time after it
has become solid
9. Produce a graph of your results (temperature y-axis, time x-axis)
10. Analyse your results according to the stages
Procedures and Techniques
Learning Aim B: Undertaking calorimetry to study cooling curves
By Zohal Nadeem
Keeping up the standards
Investigating the cooling curve of stearic acid
INTRODUCTION:
I am a newly appointed technical assistant at Chemcalequip and as part of the induction period, I must
demonstrate skills that I have learnt in a range of practical procedures and techniques. This means
that, I need to show how to use a calorimeter and associated equipment to produce enough data to
generate accurate analysis, evaluation and determination for the rate of cooling of substances.
A cooling curve represents the change in state of substances usually from a liquid to a solid or a gas to
a solid. In this experiment, the cooling curve of stearic acid is shown in a line graph so we can
observe the melting point and freezing point. Gas molecules are separated further apart from one
another and can move around freely whereas liquid molecules are kept closer together and are free to
flow easily around each other depending on the container shape. Finally, the solid state are molecules
that are held in an arranged, regular pattern held firmly together and can only vibrate and cannot be
compressed or poured. Kinetic theory states that as temperature increases, the speed of gas particles
increases. This suggests that thermal expansion takes place due to temperature change.
Also, the stearic acid molecules have hydrogen bonds and hydrogen bonds are known as
intermolecular forces of attraction. The solid stearic acid has permanent molecule bonds and in the
liquid state, stearic acid molecules can slide over each other because the bonds are breaking and
forming.
Stearic acid is a saturated fatty acid mainly made by the hydrolysis of animal, vegetable oils and fats.
Stearic acid has many applications for human use. For example, stearic acid is used in personal care
products such as sunscreen, lotions and moisturisers, cosmetics and lubricants. Therefore, stearic acid
is seen as effective and consumed by a large population.
In this report, I will be constructing an experiment for the cooling curve of stearic acid. The aim of
this experiment is to observe the changes of state, analyse the temperature change and the different
rates of cooling curve for stearic acid.
RISK ASSESSMENT:
Before, during and after the experiment, it is important to carry out health and safety measures to
prevent injuries and ensure a safe environment is obtained. The use of lab gear must be followed
which involves wearing safety goggles, making sure hair is tied up and wearing lab coats. In addition,
the thermometer must not be removed from the solid stearic acid because it will break.
The use of glassware creates the risks of cutting and bleeding. So, we had to wear safety goggles and
handle glassware carefully. The area must be cleared immediately and a teacher must be present for
assistance if there was broken glassware. Another hazard is boiling water, so the risk of burns could
occur. To prevent burns, we had to wear safety goggles and gloves. In addition, stearic acid is an
irritant so we had to make sure the room was properly ventilated so the windows were open and we
, wore safety goggles to prevent breathing difficulties such as asthma attacks. Also, the kettle contained
boiling water so we had to handle the boiling water carefully to prevent spillages and burns.
METHOD:
Equipment/Apparatus:
Beaker (250 ml^3)
Tripod
Gauze
Heat resistant mat
Bunsen burner
Boiling tube
Alcohol thermometer
Stopwatch
Tongs
Test tube rack
Method for cooling curve of stearic acid experiment:
The method below was extracted from the Pearson BTEC National Applied Science Book, Unit 2:
Page 114 and Page 115
1. Calibrate the alcohol thermometer using ice water
2. Obtain a suitable quantity of stearic acid and place into a boiling tube
3. Place the boiling tube into a beaker of freshly boiled water
4. Place a thermometer into the boiling tube (in preparation to record the drop in temperature as
the acid cools)
5. As the stearic acid heats up, it will begin to melt
6. Record the highest temperature of the now liquid stearic acid
7. Remove the boiling tube from the beaker of hot water using tongs and allow to cool in a tube
rack
8. Record the temperature over a period at set intervals as the acid cools and for a time after it
has become solid
9. Produce a graph of your results (temperature y-axis, time x-axis)
10. Analyse your results according to the stages
