Open main menu
Key Stage Wiki β

Difference between revisions of "Bond Energy"

(Created page with "==Key Stage 4== ===Meaning=== '''Bond Energy''' is the energy needed to break a chemical bond between two atoms. ===About Bond Energy=== : When Ch...")
 
 
(6 intermediate revisions by one other user not shown)
Line 1: Line 1:
−
==Key Stage 4==
+
==Key Stage 4 Higher==
 
===Meaning===
 
===Meaning===
 
'''Bond Energy''' is the [[energy]] needed to break a [[Chemical Bond|chemical bond]] between two [[atom]]s.
 
'''Bond Energy''' is the [[energy]] needed to break a [[Chemical Bond|chemical bond]] between two [[atom]]s.
Line 5: Line 5:
 
===About Bond Energy===
 
===About Bond Energy===
 
: When [[Chemical Bond|chemical bonds]] are formed [[energy]] is released to the surroundings increasing the [[temperature]]. An [[exothermic]] process]].
 
: When [[Chemical Bond|chemical bonds]] are formed [[energy]] is released to the surroundings increasing the [[temperature]]. An [[exothermic]] process]].
−
: To break [[Chemical Bond|chemical bonds]] [[energy]] is needed to separate the [[atom]]s, decreasing the [[temperature]] of the [[surroundings]]. An [[endothermic]] process]].
+
: To break [[Chemical Bond|chemical bonds]] [[energy]] is needed to separate the [[atom]]s, decreasing the [[temperature]] of the surroundings. An [[endothermic]] process]].
  
 
===Examples===
 
===Examples===
Line 50: Line 50:
 
| style="height:20px; width:150px; text-align:center;" |391
 
| style="height:20px; width:150px; text-align:center;" |391
 
|}
 
|}
 +
 +
These can be used to calculate the [[energy]] released per [[mole]] in a [[Chemical Reaction|chemical reaction]].
 +
 +
'''Example 1'''
 +
{| class="wikitable"
 +
|-
 +
|[[File:StructuralDiagramMethane+Oxygen.png|center|500px]]
 +
|-
 +
| style="height:20px; width:200px; text-align:center;" |In the [[Chemical Reaction|reaction]] between [[Methane]] and [[Oxygen]] the [[Chemical Bond|chemical bonds]] in the [[reactant]]s must be broken first before the [[Chemical Bond|bonds]] in the [[product]]s are formed.
 +
|}
 +
 +
There are 4 C-H [[Chemical Bond|bonds]] and 2 O=O [[Chemical Bond|bonds]].
 +
 +
4 x 413 + 2 x 498 = 2648kJ
 +
 +
Therefore 2648kJ/mol are needed to break the [[Chemical Bond|bonds]] in the [[reactant]]s.
 +
 +
There are 2 C=O [[Chemical Bond|bonds]] and 4 O-H [[Chemical Bond|bonds]].
 +
 +
2 x 799 + 4 x 464 = 3454kJ
 +
 +
Therefore 3454kJ/mol is released when the [[Chemical Bond|bonds]] in the [[product]]s form.
 +
 +
Once the [[Chemical Reaction|reaction]] is complete 806kJ will be released.
 +
 +
'''Example 2'''
 +
{| class="wikitable"
 +
|-
 +
|[[File:StructuralDiagramHydrogen+Nitrogen.png|center|500px]]
 +
|-
 +
| style="height:20px; width:200px; text-align:center;" |In the [[Chemical Reaction|reaction]] between [[Hydrogen]] and [[Nitrogen]] the [[Chemical Bond|chemical bonds]] in the [[reactant]]s must be broken first before the [[Chemical Bond|bonds]] in the [[product]]s are formed.
 +
|}
 +
 +
There are 3 H-H [[Chemical Bond|bonds]] and 1 N≡N [[Chemical Bond|bonds]].
 +
 +
3 x 436 + 1 x 941 = 2249kJ
 +
 +
Therefore 2249kJ/mol are needed to break the [[Chemical Bond|bonds]] in the [[reactant]]s.
 +
 +
There are 6 N-H [[Chemical Bond|bonds]].
 +
 +
6 x 391 = 2346kJ
 +
 +
Therefore 2346kJ/mol is released when the [[Chemical Bond|bonds]] in the [[product]]s form.
 +
 +
Once the [[Chemical Reaction|reaction]] is complete 97kJ will be released.
 +
 +
===References===
 +
====AQA====
 +
:[https://www.amazon.co.uk/gp/product/1782945571/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945571&linkCode=as2&tag=nrjc-21&linkId=9e29fad914244909903e5e93f8a01d62 ''Bond energies, page 63, GCSE Chemistry; The Revision Guide, CGP, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/1471851346/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851346&linkCode=as2&tag=nrjc-21&linkId=3ac654f4b0da781c49c855a1af4c92ea ''Bond energies, pages 133-5, GCSE Chemistry, Hodder, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/178294639X/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=178294639X&linkCode=as2&tag=nrjc-21&linkId=51599bb45a2bfaf7c1b6a978b2ca2616 ''Bond energies, pages 158, 159, GCSE Combined Science Trilogy; Chemistry, CGP, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/1782945962/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945962&linkCode=as2&tag=nrjc-21&linkId=476bb5c8d1dfb5c08ac81b6d4d1c98d8 ''Bond energies, pages 183, 184, GCSE Chemistry, CGP, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/1471851354/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1471851354&linkCode=as2&tag=nrjc-21&linkId=9012a0d354024419214fb3ad5ac44ba0 ''Bond energies, pages 235-7, GCSE Combined Science Trilogy 1, Hodder, AQA '']
 +
:[https://www.amazon.co.uk/gp/product/0198359381/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359381&linkCode=as2&tag=nrjc-21&linkId=47c8d1ae58d8b3a5e2094cd447154558 ''Bond energy, pages 117-119, GCSE Chemistry; Third Edition, Oxford University Press, AQA '']
 +
 +
====Edexcel====
 +
:[https://www.amazon.co.uk/gp/product/1782945741/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945741&linkCode=as2&tag=nrjc-21&linkId=30da4f2178da182547b62a7329d13b57 ''Bond energies, page 136, GCSE Combined Science; The Revision Guide, CGP, Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1782945725/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945725&linkCode=as2&tag=nrjc-21&linkId=694be7494de75af3349537d34e13f7f0 ''Bond energies, page 85, GCSE Chemistry; The Revision Guide, CGP, Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1782948147/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782948147&linkCode=as2&tag=nrjc-21&linkId=f63dcd8345f4e49c717b39a228a36c7c ''Bond energies, pages 248-250, GCSE Chemistry, CGP, Edexcel  '']
 +
:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Bond energy, page 147, GCSE Chemistry, Pearson, Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Bond energy, page 261, GCSE Combined Science, Pearson Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1292120215/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120215&linkCode=as2&tag=nrjc-21&linkId=8f96ddb76196848bafdb124354e4cf77 ''Bonds; energy calculations, page 147, GCSE Chemistry, Pearson, Edexcel '']
 +
:[https://www.amazon.co.uk/gp/product/1292120193/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1292120193&linkCode=as2&tag=nrjc-21&linkId=572df39392fb4200db8391d98ae6314e ''Bonds; energy calculations, page 261, GCSE Combined Science, Pearson Edexcel '']
 +
 +
====OCR====
 +
:[https://www.amazon.co.uk/gp/product/1782945679/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=1782945679&linkCode=as2&tag=nrjc-21&linkId=a2db42f7b4bdf10cafaafa3bb9120940 ''Bond energies, page 42, GCSE Chemistry; The Revision Guide, CGP, OCR Gateway '']
 +
:[https://www.amazon.co.uk/gp/product/0198359829/ref=as_li_tl?ie=UTF8&camp=1634&creative=6738&creativeASIN=0198359829&linkCode=as2&tag=nrjc-21&linkId=90e8d7b4f039d53035238fa0320fe00b ''Bond energies, pages 106-107, Gateway GCSE Chemistry, Oxford, OCR  '']

Latest revision as of 11:22, 1 December 2019

Contents

Key Stage 4 Higher

Meaning

Bond Energy is the energy needed to break a chemical bond between two atoms.

About Bond Energy

When chemical bonds are formed energy is released to the surroundings increasing the temperature. An exothermic process]].
To break chemical bonds energy is needed to separate the atoms, decreasing the temperature of the surroundings. An endothermic process]].

Examples

Some common bond energies are given in the table below.

Bond Energy in kJ/mol
H-H 436
O=O 498
N≡N 941
C-C 347
C=C 614
C≡C 839
C-H 413
O-H 464
C=O 799
Cl-Cl 243
H-Cl 432
N-H 391

These can be used to calculate the energy released per mole in a chemical reaction.

Example 1

 
In the reaction between Methane and Oxygen the chemical bonds in the reactants must be broken first before the bonds in the products are formed.

There are 4 C-H bonds and 2 O=O bonds.

4 x 413 + 2 x 498 = 2648kJ

Therefore 2648kJ/mol are needed to break the bonds in the reactants.

There are 2 C=O bonds and 4 O-H bonds.

2 x 799 + 4 x 464 = 3454kJ

Therefore 3454kJ/mol is released when the bonds in the products form.

Once the reaction is complete 806kJ will be released.

Example 2

 
In the reaction between Hydrogen and Nitrogen the chemical bonds in the reactants must be broken first before the bonds in the products are formed.

There are 3 H-H bonds and 1 N≡N bonds.

3 x 436 + 1 x 941 = 2249kJ

Therefore 2249kJ/mol are needed to break the bonds in the reactants.

There are 6 N-H bonds.

6 x 391 = 2346kJ

Therefore 2346kJ/mol is released when the bonds in the products form.

Once the reaction is complete 97kJ will be released.

References

AQA

Bond energies, page 63, GCSE Chemistry; The Revision Guide, CGP, AQA
Bond energies, pages 133-5, GCSE Chemistry, Hodder, AQA
Bond energies, pages 158, 159, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Bond energies, pages 183, 184, GCSE Chemistry, CGP, AQA
Bond energies, pages 235-7, GCSE Combined Science Trilogy 1, Hodder, AQA
Bond energy, pages 117-119, GCSE Chemistry; Third Edition, Oxford University Press, AQA

Edexcel

Bond energies, page 136, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Bond energies, page 85, GCSE Chemistry; The Revision Guide, CGP, Edexcel
Bond energies, pages 248-250, GCSE Chemistry, CGP, Edexcel
Bond energy, page 147, GCSE Chemistry, Pearson, Edexcel
Bond energy, page 261, GCSE Combined Science, Pearson Edexcel
Bonds; energy calculations, page 147, GCSE Chemistry, Pearson, Edexcel
Bonds; energy calculations, page 261, GCSE Combined Science, Pearson Edexcel

OCR

Bond energies, page 42, GCSE Chemistry; The Revision Guide, CGP, OCR Gateway
Bond energies, pages 106-107, Gateway GCSE Chemistry, Oxford, OCR
Retrieved from "https://keystagewiki.com/index.php?title=Bond_Energy&oldid=20874"