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==Key Stage 4==
===Meaning===
'''Dynamic Equilibrium''' is when a [[Reversible Reaction|reversible reaction]] has been going long enough that the forward [[Chemical Reaction|reaction]] and the back [[Chemical Reaction|reaction]] happen at the same [[Rate of Reaction|rate]] causing a constant quantity of [[reactant]]s and [[product]]s in the [[Reaction Mixture|reaction mixture]].
===About Dynamic Equilibrium===
====Foundation====
: During '''dynamic equilibrium''' the amount of [[reactant]]s and [[product]]s is constant. However, the [[Chemical Reaction|reactions]] have not stopped taking place.
: When the [[Reaction Mixture|reaction mixture]] is initially added to a [[Reaction Vessel|reaction vessel]] the [[Rate of Reaction|rate]] of the forward [[Chemical Reaction|reaction]] is high. As the [[Chemical Reaction|reaction]] progresses the [[concentration]] of original [[reactant]]s decreases, slowing [[Rate of Reaction|rate of reaction. Meanwhile the [[concentration]] of [[product]]s increases, which increases the rate of the back [[Chemical Reaction|reaction]]. Once the two [[Rate of Reaction|rates of reaction]] are equal then the [[Reaction Mixture|reaction mixture]] is in [[Dynamic Equilibrium|dynamic equilibrium]].
====Higher====
: The position of the '''dynamic equilibrium''' (the [[ratio]] of [[reactant]]s to [[product]]s) can be affected by the [[temperature]] and by the [[Gas Pressure|pressure]].
=====Temperature and Dynamic Equilibirum=====
: 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]].
=====Pressure and Dynamic Equilibirum=====
: For [[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'''.
: 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.
Hydrogen + Nitrogen ⇌ Ammonia
<chem> 3H2(g) + N2(g) <=> 2NH3(g) </chem>
: 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
<chem> NH4Cl(s) <=> NH3(g) + HCl(g) </chem>
: 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.