View source for Equilibrium Position (Chemistry)

==Key Stage 4 Higher==
===Meaning===
'''Equilibrium position''' is the the [[ratio]] of [[reactant]]s to [[product]]s when a [[Reversible Reaction|reversible reaction]] is in a state of [[Dynamic Equilibrium|dynamic equilibrium]].

===About the Equilibrium Position===
: The '''equilibrium position''' can be affected by the [[temperature]] and by the [[Gas Pressure|pressure]].
: The availability of raw [[material]]s can affect the choice of '''equilibrium position'''. Where those raw [[material]]s are rare or expensive it is better to have an '''equilibrium position''' which strongly favours the forward reaction.
=====Temperature and Equilibrium Position=====
: An increase in [[temperature]] will increase the [[Rate of Reaction|rate]] of an [[endothermic]] [[Chemical Reaction|reaction]] it requires [[energy]] from the environment to take place.
: This means for an [[endothermic]] forward [[Chemical Reaction|reaction]] a higher [[temperature]] will result in more [[product]] being formed. However, for an [[exothermic]] forward [[Chemical Reaction|reaction]] less product will be formed as the back [[Chemical Reaction|reaction]] will be [[endothermic]] and would increase its [[Rate of Reaction|rate]] with higher [[temperature]].
: High [[temperature]]s are more expensive because they require [[energy]] to maintain a high [[temperature]]. This means it may be more cost effective not to go for the best '''equilibrium position''' for the [[Chemical Reaction|reaction]].

=====Pressure and Equilibrium Position=====
: For [[Chemical Reaction|reaction]]s involving a [[gas]] as either one of the [[reactant]]s or [[product]]s changing the pressure will affect the position of [[Dynamic Equilibrium|dynamic equilibrium]].
: The number of [[mole]]s of [[gas]] in the [[reactant]]s and [[product]]s will determine which direction of [[Chemical Reaction|reaction]] is favoured by higher [[Gas Pressure|pressure]].
: If the forward [[Chemical Reaction|reaction]] [[product|produces]] more [[mole]]s of [[gas]] than the back [[Chemical Reaction|reaction]] then high [[Gas Pressure|pressure]] will reduce the amount of [[product]]s formed.
: If the forward [[Chemical Reaction|reaction]] [[product|produces]] less [[mole]]s of [[gas]] than the back [[Chemical Reaction|reaction]] then high [[Gas Pressure|pressure]] will increase the amount of [[product]]s formed.

===Examples===
Hydrogen + Nitrogen ⇌ Ammonia

<math> 3H2(g) + N2(g) <=> 2NH3(g) </math>
: In this [[Reversible Reaction|reversible reaction]] there are more [[mole]]s of [[gas]] in the [[reactant]]s than the [[product]]s so higher [[Gas Pressure|pressure]] will favour the forward [[Chemical Reaction|reaction]] and the [[Equilibrium Position|equilibrium position]] will have a greater [[concentration]] of [[product]]s than [[reactant]]s.

Ammonium Chloride ⇌ Ammonia + Hydrochloric Acid

<math> NH4Cl(s) <=> NH3(g) + HCl(g) </math>
: In this [[Reversible Reaction|reversible reaction]] there are more [[mole]]s of [[gas]] in the [[product]]s than the [[reactant]] so higher [[Gas Pressure|pressure]] will favour the back [[Chemical Reaction|reaction]] and the [[Equilibrium Position|equilibrium position]] will have a greater [[concentration]] of [[reactant]] than [[reactant]]s.

===References===
====OCR====

:[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 ''Equilibrium position, pages 188-191, Gateway GCSE Chemistry, Oxford, OCR  '']