Assignment 2B: Calorimetry & Cooling Curves
NAME: ___________________________
I certify that the work submitted for this
assignment is my own. I have referenced any
sources used in the work. I understand that a false
declaration is a form of malpractice.
DATE: ________________
,Introduction
A cooling curve shows the decrease in temperature of a substance in the formation of a graph,
within the cooling curve, the melting and boiling points can also be seen as a horizontal line due to
the energy being used to strengthen the intermolecular forces rather than decreasing the
temperature. This stage is known as an isothermal process due to the temperature staying constant.
The diagonal or curved lines are then visible as the cooling of the substance, with the decrease in
temperature due to less kinetic energy as a result of a drop in the mean thermal energy.
Cooling curves are essential in industry to be able to determine melting and boiling points that can
be accurately determined by repeating and recording the cooling process of a substance to gain
reliable data. This data can then be used to identify any impurities in a substance that would result in
a variance in melting and boiling points. Furthermore, the graph can also show the decrease in
energy and the time taken for the substance to decrease in temperature.
When substances change state from gas to liquid, the intermolecular forces between particles
becomes stronger and forces the particles to move towards each other, from liquid to solid the
intermolecular forces become even stronger and result in the particles vibrating. These changes
occur as less kinetic energy is transferred, resulting in the greater attraction between particles.
Brief description of states of matter
At solid state particles are arranged in fixed rows and vibrate, the intermolecular forces are also
strongest at this point, they also include a definitive shape and volume. Liquids are easily malleable
and so obtain shapes of the container they are present in and like solids, hold a specific volume.
Gases are completely unique with no exact shape or volume.
Risk Assessment
Hazard Nature Mitigation
Electrical hot plates, boiling Burns Take caution
water, hot wax Electric Shock Ensuring dry hands
before handling
electrical equipment
Turning off and
removing equipment if
there is a spillage
Stearic Acid (CLEAPPS, 2022) Dust (irritant if Keep as a whole
inhaled) Avoid unnecessary
breaking up
Paraffin Wax (CLEAPPS, 2022) NOT HAZARDOUS
Method and Equipment
Methods of measuring temperature with advantages and disadvantages
Digital Thermometers
Digital thermometers contain thermocouples and thermistors which are one way of measuring
temperature, two wires composed of different metals are required which come together to create a
junction, voltage can then be measured within the circuit and correlates to a temperature.
Thermistors involve a thermally sensitive resistor that differs in resistance with change in
temperature (Cook, 2023). This was the thermometer used to construct my cooling curve.
, Digital Thermometers – advantages & disadvantages (StudyKaki, 2021)
Advantages Disadvantages
Durable Can be vulnerable to corrosion with different
reactivity in metals
Temperature easily measured at a specific spot Common degrees of error lie between 10 c and
0
2 c
Recognise large temperature differences Do not recognise small temperature changes
quickly
Large temperature range measurable from Nearby electricals can cause inaccuracies in
0 0
−100 c to 2500 c readings due to low voltage outputs
Readings are objective
Infrared Thermometers
Infrared radiation that is reflected and emitted from a surface is tunnelled into the thermometer
into a detector called a thermopile. The thermopile then converts the radiation into an electrical
signal and displays a number.
Infrared Thermometers – advantages & disadvantages (Klump, N.D.)
Advantages Disadvantages
Large range of temperatures Inequality between surface reflectance, dull
metals easier to measure
Quick and easy to use Unable to measure internally
No-contact necessary Less accurate due to no contact
Alcohol filled thermometers.
With an increase in temperature the alcohol located within the thermometer expands due to the
molecules within the alcohol expanding and moving further apart. We used both full emersion and
76mm emersion.
Alcohol filled thermometers – advantage & disadvantages (Geerts, 2002)
Advantages Disadvantages
Alcohol is non – toxic Can be subjective
Lower temperatures offer greater accuracy Colourless so requires a dye
Freezing point is low Evaporation can occur so less durability
Mercury filled thermometers.
Similar to alcohol filled thermometers the mercury within the thermometer expands with heat and
contracts when cooled.
Mercury filled thermometers – advantages & disadvantages (Geerts, 2002)
Advantages Disadvantages
High accuracy Mercury is toxic so if the thermometer breaks
poisoning could occur
NAME: ___________________________
I certify that the work submitted for this
assignment is my own. I have referenced any
sources used in the work. I understand that a false
declaration is a form of malpractice.
DATE: ________________
,Introduction
A cooling curve shows the decrease in temperature of a substance in the formation of a graph,
within the cooling curve, the melting and boiling points can also be seen as a horizontal line due to
the energy being used to strengthen the intermolecular forces rather than decreasing the
temperature. This stage is known as an isothermal process due to the temperature staying constant.
The diagonal or curved lines are then visible as the cooling of the substance, with the decrease in
temperature due to less kinetic energy as a result of a drop in the mean thermal energy.
Cooling curves are essential in industry to be able to determine melting and boiling points that can
be accurately determined by repeating and recording the cooling process of a substance to gain
reliable data. This data can then be used to identify any impurities in a substance that would result in
a variance in melting and boiling points. Furthermore, the graph can also show the decrease in
energy and the time taken for the substance to decrease in temperature.
When substances change state from gas to liquid, the intermolecular forces between particles
becomes stronger and forces the particles to move towards each other, from liquid to solid the
intermolecular forces become even stronger and result in the particles vibrating. These changes
occur as less kinetic energy is transferred, resulting in the greater attraction between particles.
Brief description of states of matter
At solid state particles are arranged in fixed rows and vibrate, the intermolecular forces are also
strongest at this point, they also include a definitive shape and volume. Liquids are easily malleable
and so obtain shapes of the container they are present in and like solids, hold a specific volume.
Gases are completely unique with no exact shape or volume.
Risk Assessment
Hazard Nature Mitigation
Electrical hot plates, boiling Burns Take caution
water, hot wax Electric Shock Ensuring dry hands
before handling
electrical equipment
Turning off and
removing equipment if
there is a spillage
Stearic Acid (CLEAPPS, 2022) Dust (irritant if Keep as a whole
inhaled) Avoid unnecessary
breaking up
Paraffin Wax (CLEAPPS, 2022) NOT HAZARDOUS
Method and Equipment
Methods of measuring temperature with advantages and disadvantages
Digital Thermometers
Digital thermometers contain thermocouples and thermistors which are one way of measuring
temperature, two wires composed of different metals are required which come together to create a
junction, voltage can then be measured within the circuit and correlates to a temperature.
Thermistors involve a thermally sensitive resistor that differs in resistance with change in
temperature (Cook, 2023). This was the thermometer used to construct my cooling curve.
, Digital Thermometers – advantages & disadvantages (StudyKaki, 2021)
Advantages Disadvantages
Durable Can be vulnerable to corrosion with different
reactivity in metals
Temperature easily measured at a specific spot Common degrees of error lie between 10 c and
0
2 c
Recognise large temperature differences Do not recognise small temperature changes
quickly
Large temperature range measurable from Nearby electricals can cause inaccuracies in
0 0
−100 c to 2500 c readings due to low voltage outputs
Readings are objective
Infrared Thermometers
Infrared radiation that is reflected and emitted from a surface is tunnelled into the thermometer
into a detector called a thermopile. The thermopile then converts the radiation into an electrical
signal and displays a number.
Infrared Thermometers – advantages & disadvantages (Klump, N.D.)
Advantages Disadvantages
Large range of temperatures Inequality between surface reflectance, dull
metals easier to measure
Quick and easy to use Unable to measure internally
No-contact necessary Less accurate due to no contact
Alcohol filled thermometers.
With an increase in temperature the alcohol located within the thermometer expands due to the
molecules within the alcohol expanding and moving further apart. We used both full emersion and
76mm emersion.
Alcohol filled thermometers – advantage & disadvantages (Geerts, 2002)
Advantages Disadvantages
Alcohol is non – toxic Can be subjective
Lower temperatures offer greater accuracy Colourless so requires a dye
Freezing point is low Evaporation can occur so less durability
Mercury filled thermometers.
Similar to alcohol filled thermometers the mercury within the thermometer expands with heat and
contracts when cooled.
Mercury filled thermometers – advantages & disadvantages (Geerts, 2002)
Advantages Disadvantages
High accuracy Mercury is toxic so if the thermometer breaks
poisoning could occur
