Calorimeter
A calorimeter is a scientific instrument used to measure the heat of chemical reactions, determining how much heat is absorbed or released during these processes. The term "calorimeter" comes from Latin and Greek roots meaning "heat" and "to measure," respectively. Calorimetry, the science behind these measurements, typically involves either constant atmospheric pressure or constant volume conditions. Commonly, calorimeters are employed to measure heat changes in solutions, often utilizing water as the medium.
The first calorimeter was invented by the French chemist Antoine-Laurent Lavoisier, who conducted experiments with various substances to explore heat generation during combustion and respiration. Modern calorimeters come in various forms, from simple ones like the coffee-cup calorimeter, made from Styrofoam, to sophisticated devices with advanced features. The effectiveness of a calorimeter relies on accurate temperature measurement before and after a reaction, which helps calculate heat capacity and the enthalpy of reactions. Special types, such as bomb calorimeters, are designed for measuring heat in high-energy reactions and operate under constant volume conditions.
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Calorimeter
A calorimeter is a scientific measuring device to measure the heat of a reaction. The calorimeter can measure both the heat absorbed or released during a chemical reaction. The word calorimeter is derived from Latin and Greek; calor, the Latin term for heat, and meter, Greek meaning to measure. The science of measuring the amount of heat is known as calorimetry, from the same etymology. There are two ways in which calorimeter measurements are conducted. These comprise a constant atmospheric pressure or a constant volume. A common usage of a calorimeter is to measure heat changes in a solution, very often with water as a basis. The laws of thermodynamics, especially the first law that maintains that heat lost by a system is absorbed into the surroundings, is relevant to the calorimetry study. Equipment and materials required generally comprise a volume of liquid or water, a source of heat, and a calorimeter or equivalent container.
Background
Antoine-Laurent Lavoisier (1743-94), a French chemist who revolutionized chemical research outcomes, invented the first calorimeter. The initial device he created was an ice calorimeter, wherein he first experimented with a candle, and then a living being (a guinea pig), to determine the amount of heat that would be generated. His experiment resulted in the finding that no matter the object, energy is released during this system or form of combustion, be it through the flame or respiration. Lavoisier's identification of the elements of carbon, hydrogen, and oxygen were extremely significant discoveries in the scientific world; moreover, his discovery of the role oxygen played in respiration and combustion was particularly pertinent for the field of calorimetry. The calorimeter is generally made up of water placed in some kind of chamber. Added to this is a chemical system placed inside so that an energy change transpires and is then measured accordingly. Ultimately, the main measurements supply information about the heat capacity, enthalpy of fusion or vaporization, and the enthalpy of the chemical reaction.
The theory of calorimetry and the use of calorimeters are based on the premise that energy is released most commonly as heat energy, although other energy releases can take place via alternative means. The measuring of the heat energy is the science known as calorimetry. Energy changes that occur in combustion, such as burning fuel, or the manifestation of energy changes when substances are placed in a solution, are examples of reactions that are measured by the calorimetry method.
The steps involved in measuring temperature and the changes occurring over time are determined as follows: T1 indicates the initial temperature of the reactants (the substances or products that will undergo a chemical reaction) as the experiment begins; T2 indicates the maximum temperature reached in the calorimeter when the exothermic reaction has taken place. An exothermic reaction implies the transference of energy to the surrounding environment. This is in contrast to an endothermic reaction where energy is taken in from the outside.
Overview
Types of Calorimeters. A calorimeter may be purchased as an upmarket scientific device or devised from a simple piece of equipment. A Styrofoam cup may be used as it maintains the heat temperature for a period of time by acting as an insulating chamber, so the heat does not escape into the environment. The Styrofoam model calorimeter is often referred to as the coffee-cup calorimeter. A thermometer is placed in a hole on top of the cup to read the temperature. A more expensive calorimeter will comprise a more sophisticated lid and thermometer insertion mechanism, including a stirrer. It is essential that the calorimeter is dry at the commencement of the process.
Temperature Measurement. Since the purpose of a calorimeter is to measure the heat of a reaction, such reactions are often initiated by a process of enclosing the heat. When the substance known as the reactant is placed in this enclosed or insulated space, such as in the calorimeter, a reaction is instigated. The temperature is measured prior to the reaction and after it has occurred. Once the difference in temperature is calculated, scientists are able to assess the status of the heat that has been released during the reactive process.
Heat Capacity. Heat capacity is a key to understanding and evaluating the measurement of heat reaction. The quantity of heat that is needed to raise the calorimeter’s temperature by 1K (K being Kelvin, a thermodynamic temperature measurement unit) is what determines heat capacity. The heat capacity is not calculated at the same time as the heat reaction, but rather before or after this is measured. The exact determination of heat capacity involves a procedure whereby a specific amount of heat is transferred into the calorimeter. Thereafter, the increase in temperature is checked, indicating the heat capacity of the calorimeter. Temperatures may show a minute difference and thus require an extremely sensitive thermometer to measure the changes accurately.
Bomb Calorimeter. One of the calorimeters employed to measure a large reaction is a bomb calorimeter. Called a bomb calorimeter due to the combustion reaction it measures, this calorimeter is made out of steel and is explosive-proof. The volume of the bomb calorimeter remains constant during the process. The reaction of the heat is calculated by placing the special calorimeter in water so that the reaction heat is absorbed. The method of measuring the heat capacity and reaction is equivalent to methodologies of the other calorimeters. Bomb calorimetry is the term given for this form of heat measurement.
Experiments. Experiments are conducted within laboratory conditions to effectively evaluate the amount of heat generated. For instance, heat measurements per the amount of heat released and the calculation of the enthalpy of combustion per mole of substance is one such experiment. This may give rise to concepts including ideal energy levels of a person. Enthalpy, the heat content or energy at a level of constant pressure, is formulated as H (enthalpy) = E + pV, with E being internal energy, p is pressure, and V volume.
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