Що таке калориметр?

Calorimetry is the science of measuring the amount of heat transfer to or from a substance in a chemical or physical process. For this, a calorimeter is used.

A calorimeter is a calibrated device that heat is exchanged with in a way that can be measured. To measure heat transfer using a calorimeter, first, a system and its surroundings must be defined. By the First Law of Thermodynamics, any heat that is lost by the system must be absorbed by the surroundings:

$q_{system}$=$-q_{surroundings}$

The temperature change that is measured by the device is used to derive the amount of heat that is associated with a chemical reaction.

In other words, the temperature change can be used to calculate the enthalpy change per mole of substance A when two substances, A & B, are reacted, producing the formula:

$Q$ = $m$ $C_{v}$ ($T_{final}$-$T_{initial}$)

Here, $Q$ is the amount of heat in Joules, $m$ is the mass of the system in kilograms (kg), $C_{v}$ is the heat capacity of the calorimeter in Joules per Kelvin (J/K), and $T_{final}$ and $T_{initial}$ represent the final and initial temperatures.

A calorimeter will typically consist of a metallic receptacle made from materials of good conductivity (i.e. aluminum or copper) and a stirring apparatus, contained within an insulating container to prevent heat exchange with the environment. To measure the thermal changes of the system, a single opening through which a thermometer is inserted is found on the top.

Types of Calorimeters

• Adiabatic Calorimeters $\rightarrow$ used to examine runaway reactions, where heat is produced at a faster rate than it is lost

• Bomb Calorimeters $\rightarrow$ a constant volume (isochoric) calorimeter used for measuring heats of combustion and is useful for determining the amount of heat in food and fuels

• Constant Pressure Calorimeters $\rightarrow$ used to measure the change in enthalpy of a reaction in a liquid solution at constant pressure

• Differential Scanning Calorimeters (DSC) $\rightarrow$ used to measure temperature and heat flows correlated with thermal transitions in a material. DSC can be used to determine a molecules stability in a formula

(Video) Calorimeter | Reactions | Chemistry | FuseSchool

by FuseSchool-Global Education

In this video, the FuseSchool illustrates calorimeters. They show you a calorimeter's components and how to use one. They also explain some of their common applications. This short video is a great description of calorimeters.

(Video) The science of a calorimeter

by The BMJ

In this video, The BMJ youtube channel examine bomb calorimetry. You'll see a working lab use a bomb calorimeter to measure the calories in a Thanksgiving dinner. This short video will give you a better idea of how calorimetry experiments happen in a lab.