Enthalpy Change ∆H Of A Reaction - Reaction Enthalpy
Chapter Name : Thermodynamics |
Sub Topic Code : 102_11_06_04_04 |
Topic Name : Enthalpy Change ∆H Of A Reaction - Reaction Enthalpy |
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Sub Topic Name : Standard Enthalpy Of Formation |
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Introduction
·
The standard enthalpy of formation is a measure of the
energy released or consumed when one mole of a substance is created under
standard conditions from its stable elements.
·
An element is said to
be most stable at standard conditions of 298 K and 1 bar.
·
The standard enthalpy
of formation of stable elements is zero.
Pre-Requisites:
· Thermodynamic terms
· The state of a system
· Enthalpy
Activity:
Sugar has a different energy value. When its
mixed with water, the enthalpy changes and the final enthalpy of formation of
sugar water is different.
Real Life Question:
What is the enthalpy
change associated with a formation reaction?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Enthalpy | It is same as energy at low and moderate pressure |
| Standard enthalpy of formation | The standard enthalpy change for the formation of one mole of a compound from its stable elements is called Standard Molar Enthalpy of Formation. It is represented as ?fH? |
| Reference state of element | The standard enthalpy change for the formation of An element is said to be in reference state at standard conditions of 298 K temperature and 1 bar pressure. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| NCERT Chemistry 11 Table 6.2 | It gives the value of standard enthalpy of formation of different substances |
Real life uses :
Enthalpy of formation tells the amount of energy
it takes to make different substances.
Places to visit :
kitchen
Practical examples around us
| Examples | Explainations |
|---|---|
| Formation of carbon dioxide gas | Carbon and oxygen gas combine to give CO2 in atmosphere. |
What you learn in Theory:
Enthalpy changes
associated with formation reactions
What you learn in Practice:
How to calculate
standard enthalpy of reaction using standard enthalpies of formation