Measurement Of ∆U And ∆H
Chapter Name : Thermodynamics |
Sub Topic Code : 102_11_06_03_02 |
Topic Name : Measurement Of ∆U And ∆H |
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Sub Topic Name : ∆U Measurements |
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Introduction
• A bomb calorimeter is used to measure the heat absorbed by a chemical reaction at constant volume. • Here the work done = 0 as there is no volume change. • To calculate the heat released the following formula is used : ?U = qv = C ?T
Pre-Requisites:
• Thermodynamic terms • The state of a system • Enthalpy • Heat capacity
Activity:
Energy value of different food items, fuels is measured using bomb calorimeter.
Real Life Question:
How do we measure the energy associated with any chemical process at constant volume?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Calorimetry | It is the act of measuring the energy associated with chemical reactions or physical changes. |
| Calorimeter | It is an object used for measuring energy change associated with a chemical or physical process. |
| Heat capacity | The number of heat units needed to raise the temperature of a body by one degree. |
| Bomb calorimeter | It is a device used to measure the heat absorbed by a chemical reaction at constant volume. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Bomb calorimeter | It is a device used to measure the heat absorbed by a chemical reaction at constant volume. |
Real life uses :
- Food companies use Calorimetry to calculate the energy content of their product. - At chemical plants, new reaction/process is first tried at small-scale in a calorimeter to see how much heat is evolved, to know if the cooling system will be able to handle it or not.
Places to visit :
Home.
Practical examples around us
| Examples | Explainations |
|---|---|
| Cereal box | The energy associated with combustion of food is measured using bomb calorimeter. |
| Oil can | The combustion energy associated with the oil is measured using bomb calorimeter. |
What you learn in Theory:
Measurement of energy associated with a physical or chemical process at constant volume.
What you learn in Practice:
Applications of Calorimetry at constant volume (bomb calorimeter).