What is Calorimetry?
Calorimetry is the process that measures the amount of heat released and gained by the bodies through physical contact due to the thermal difference between them. The calorimeter is used to measure the transfer of heat from one body to another due to the temperature difference. The process in which bodies release energy in the form of heat is known as exothermic reactions, and those processes where the heat is absorbed are known as endothermic reactions.
In this article, the concept of a calorimeter is defined along with the types of the calorimeter and the uses of the calorimeter. It also discusses the function of the calorimeter. Further, we will also discuss the calorimetry principle and calorimetry experiment in the upcoming sections.
A calorimeter is a device that is used for the measurement of the heat capacity of the material generated during the reaction. The type of reaction can be physical, chemical, or mechanical. The function of the calorimeter is to determine the thermal changes that occurred in the body during the reaction. It is extensively used in thermochemistry for determining the thermal properties of a material. The thermal properties involve enthalpy, stability, heat capacity, etc.
Principle of Calorimetry
The principle of calorimetry states that the body/object at a higher temperature releases the heat and the body/object at a lower temperature absorbs the heat. Its principle defines the law of conservation energy. According to this, the total heat loss by the object at a higher temperature is equal to the total heat absorbed by the object at a lower temperature.
The calorimetry process is possible only when two bodies at different temperatures are kept in physical contact and the heat exchange process continues until the thermal equilibrium is established.
The calorimeter is a physical instrument of measurement which is used to measure the heat and its related parameters. The calorimeter consists of vessels/containers which are good conductors of heat such as copper, aluminium, etc. The metallic vessel consists of a stirrer which helps in stirring the contents of the vessel. During the stirring process, the heat loss is prevented with the insulation provided around the stirrer. The thermometer is accommodated through a small opening that monitors the change in temperature taking place inside the calorimeter.
A Schematic View of the Calorimeter
A certain amount of fuel is burned inside the calorimeter. The burning of fuel heats the water which is contained in the metallic vessel. The heat lost from the fuel is transferred as the heat absorbed by the water indicating the law of conservation of energy. Accurate results can be obtained by incorporating the insulation of the calorimeter from the external environment.
The heat change of the water is determined with the incorporated thermometer. The heat capacity of water and the amount of converted energy can be identified using the readings of the thermometer.
Types of Calorimeters
1. Adiabatic Calorimeters
It is a type of calorimeter indicating a runaway reaction. Due to the adiabatic environment, heat generation by the fabric test sample will lead to an extension of the sample owing to the increase in temperature, leading to intensification of the reaction. Though the name is adiabatic calorimeter, it does not have the complete adiabatic environment as a certain amount of heat is lost through the sample holder. Therefore, a phi-factor (mathematical correction factor) is used to adjust the result in accordance with the heat losses.
2. Bomb Calorimeters
A bomb is a type of constant-volume calorimeter that measures the heat of combustion of a specific reaction. The fuel is ignited using electrical energy which helps the fuel burn and increases the temperature of the surrounding air. This air on expansion escapes the copper tube which releases the air out of the calorimeter. The copper tube, which is at high temperature, transfers the heat to the water outside this tube, and this temperature difference helps in identifying the calorie content of the fuel.
3. Differential Scanning Calorimeters
The differential scanning calorimeter allows heat to flow into the test sample which is encompassed in a small aluminium capsule. The measurement of heat flow is differential in nature which means the heat flow values are compared to the heat flow into an empty reference capsule.
4. Isothermal Titration Calorimeter
A titration experiment is followed to identify the heat of reaction in the case of an isothermal titration calorimeter. This technique is growing its significance in the biochemistry sector as it facilitates the identification of substrate binding to enzymes. There are other sectors that are utilising this technique such as the pharmaceutical industry.
Applications of Calorimeters
Calorimeters play a vital role in everyday life. The uses of calorimeters are used to control the metabolic rates of the human body and simultaneously maintain the temperature of the body. As the calorimeter is used to measure the heat of a reaction, it is a crucial part of thermodynamics.
There are various uses of calorimeters in thermodynamic applications in thermal industries and the most common types of calorimeters used in everyday life are bomb calorimeter and coffee-cup calorimeter.
The heat generated by the sensors in reactors is measured using a reaction calorimeter.
Enthalpy change can also be measured using a constant-pressure calorimeter.
Runtime reaction can be measured or assessed using the adiabatic calorimeter.
This article concludes with conceptual information about calorimetry, the calorimeter instrument, and the various types of calorimeters. It also answers the queries related to the components of the calorimeter and applications of the calorimeter. The article also covers various examples of calorimeters. It discusses the principle of calorimetry and what it indicates. This article explicitly discusses the calorimetry uses and calorimetry experiments.
FAQs on Calorimetry: Principle, Experiment and Applications for JEE
1. What is the working principle of a calorimeter?
The principle on which the calorimeter works is called the law of conservation of energy. The law of conservation states that the total heat lost from the hot body will be equal to the total heat gained by the cold body due to the temperature difference between them.
It clearly depicts that when two bodies at different temperatures come in contact physically, then the heat gets transferred from the higher body temperature to the lower body temperature until thermal equilibrium is attained between them.
2. What are the components of a bomb calorimeter?
Bomb calorimeters are used to precisely calculate the energy shift that occurs during a reaction. A bomb calorimeter essentially consists of a small cup to hold the sample, oxygen, a bomb made of stainless steel, water, a stirrer, a thermometer, the dewar or insulating container (to stop heat from the calorimeter from escaping to the surroundings), and an ignition circuit connected to the bomb. Using stainless steel for the bomb will ensure that there is no volume change during the reaction.
3. What is the importance of calorimetry in the JEE competitive exam?
The concept of calorimetry comes under the category of heat and thermodynamics. It is found that the topic relating to heat and thermodynamics belongs to the high weightage section in the competitive exams of JEE Main and Advanced. Such topics which are connected to heat and thermodynamics require less input and have a high advantage as an output in scoring maximum marks in it. Topics like heat and thermodynamics, fluids, gravitation, wave optics, and ray optics are some of the frequently tested topics in the JEE exam paper.