Principle Of Calorimetry

The Universe comprises energy and matters where matter includes particles, namely molecules and atoms. Moreover, the molecules and atoms with the help of energy can move invariably. So, their motion can either be that of colliding with each other or moving forward and backward. 

As a result of this motion between atoms and molecules, heat energy is formed, which is one of the fundamentals of the principles of calorimetry. Furthermore, thermal energy is present everywhere – in the human body, in volcanoes and even in the coolest spaces. It is transferable from one body to another body.

This heat flow that takes place within physical processes and chemical reactions is measurable. Additionally, the procedure of measuring heat is termed calorimetry.

What Is Calorimetry?

To define calorimetry, it can be said that it is an act of quantifying the change in the thermal energy of an object. Some of the vital highlights related to calorimetry are as follows.

• The temperature of a body or an object determines the heat amount present in that body. 

• Temperature and heat energy are directly proportional to each other. So, this means that the more the amount of heat energy the more is the temperature of a body.

• To evaluate the loss and gain of thermal energy, an object’s temperature is measured prior to and after the transfer of heat. Hence, this temperature difference ascertains the heat change of a body. 

For example:

Let us consider a hot cup of coffee or chilled ice cream, which is kept at room temperature. Eventually, after an hour or two, the coffee will cool down, and the ice cream will melt. This change happens because the coffee releases heat energy, and its temperature reduces. On the other hand, the ice cream’s temperature rises as it absorbs heat from the atmosphere.

Notably, the process of calorimetry is executed using a calorimeter. A calorimeter is a tool that measures either the quantity of heat energy gained or released or specific heat capacity.

What is the Principle of Calorimetry 

In a calorimeter, two forms of matter (desirably a liquid and a solid) are situated in contact with one another. Moreover, both bodies have distinct temperatures. Due to this arrangement, heat energy gets transferred from an object having a greater temperature to an object having a lesser temperature.

However, heat flow continues until a state of thermal equilibrium is achieved between the bodies. The principle of calorimetry signifies the “law of conservation of energy.” Hence, this statement means that the total amount of heat absorbed by the cold object is equal to the total amount of heat released by the hot object.

Formula Related to Calorimetry

The basic concept of calorimetry is as follows.

The heat released by the hot object = Heat absorbed by the cold object

The transfer of heat is evaluated with the help of a formula, which is as follows

Q = mCΔT

Where Q = Entire heat energy (J)

m = Mass of an object or body (g)

C = Specific heat capacity (J/gm K)

ΔT = Change in temperature (°C)

(Fact: 4.1813 J/gm K is the specific heat capacity of water)

Numericals on Principles of Calorimetry

(i) What is the amount of heat needed to change 1g of water by 40°C. Provided that C of water is 4.2 J/gm K.

Solution: C= 4.2 J/gm K; m= 1g; ΔT= 40, then

According to the equation Q= mCΔT,

Therefore, Q= 1 X 4.2 X 40= 168 Joules.

(ii) 1000J of heat is applied to a mass of lead 0.5kg to change its temperature from 20°C to 40°C. Determine its heat capacity.

Solution: Q= 1000J; m= 0.5kg; ΔT= (40-20)°C= 20°C, then

C= 1000/(0.5X20); C= 100 J/kg K.

Do It Yourself

1. The Study of Calorimetry is Based on Which Law?

(a) Law of Kinetic Energy   

(b) Joule’s Law   

(c) Law of Conservation of Energy   

(d) None

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The principle of calorimetry is a concept taught in 11th class physics. The concept of calorimetry is introduced in chapter 11 in the NCERT book, the chapter is called thermal properties of matter. This chapter is an extremely important part of physics, it explains in depth the notion of heat and temperature and how temperature changes are a part of our day-to-day lives. In the study of physics, it is extremely important to define the notions of heat temperature et cetera. This chapter mainly talks about what really heat is and how it can be measured. It explains the many processes by which the flow of heat takes place from one place to another. This is where the study of calorimetry becomes important.

We know that the universe consists of matter-energy, matter can be further divided into atoms and molecules and The reason why these atoms and molecules are in motion is that the energy makes them in motion. This is either done by vibrating back and forth or by bumping into each other. This movement of the atoms and molecules produces energy that we call thermal energy or heat. Calorimetry mainly deals with the heat transfer that occurs within two objects and this method is known as calorimetry.

The Vedantu’s team has done extensive research and tailored The study material on the topic principles of Kalidah Metry according to the needs of the students this article mainly deals with the definition of calorimetry their examples, it explains the principle of calorimetry, formulae related to calorimetry, along with these The Vedantu’s team has also given practice questions along with their solutions based on principles of calorimetry so that students can get a good hold over the concept of Calorimetry.

The word calorimetry when divided can be seen as two words where calorie means heat and Metry means measurement, when combined the two words means measurement of heat, therefore, calorimetry can be defined as the measurement of heat in very simple terms. The device by which colorimetry can be measured is called a calorimeter.

A calorie meter is a metallic vessel that also includes a stirrer, both vessel and stirrer are made of the same material which is copper or aluminum. To ensure that there is no heat loss the vessel is kept in a wooden jacket. There is a small opening in the outer jacket through which a mercury thermometer can be inserted.

Important topics discussed in the chapter-

11.1 Introduction

11.2 Temperature and heat

11.3 Measurement of temperature

11.4 Ideal-gas equation and absolute temperature

11.5 Thermal expansion

11.6 Specific heat capacity

11.7 Calorimetry

11.8 Change of state

11.9 Heat transfer

11.10 Newton’s law of cooling