Difference between revisions of "Dynamic Equilibrium"
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==Key Stage 4== | ==Key Stage 4== | ||
===Meaning=== | ===Meaning=== | ||
| − | '''Dynamic Equilibrium''' is when [[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]]. | + | '''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=== | ===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. | ||
Revision as of 16:02, 16 January 2019
Contents
Key Stage 4
Meaning
Dynamic Equilibrium is when a reversible reaction has been going long enough that the forward reaction and the back reaction happen at the same rate causing a constant quantity of reactants and products in the reaction mixture.
About Dynamic Equilibrium
Foundation
- During dynamic equilibrium the amount of reactants and products is constant. However, the reactions have not stopped taking place.
- When the reaction mixture is initially added to a reaction vessel the rate of the forward reaction is high. As the reaction progresses the concentration of original reactants decreases, slowing [[Rate of Reaction|rate of reaction. Meanwhile the concentration of products increases, which increases the rate of the back reaction. Once the two rates of reaction are equal then the reaction mixture is in dynamic equilibrium.
Higher
- The position of the dynamic equilibrium (the ratio of reactants to products) can be affected by the temperature and by the pressure.
Temperature and Dynamic Equilibirum
- An increase in temperature will increase the rate of an endothermic reaction it requires energy from the environment to take place.
- This means for an endothermic forward reaction a higher temperature will result in more product being formed. However, for an exothermic forward reaction less product will be formed as the back reaction will be endothermic and would increase its rate with higher temperature.
Pressure and Dynamic Equilibirum
- For reactions involving a gas as either one of the reactants or products changing the pressure will affect the position of dynamic equilibrium.
- The number of moles of gas in the reactants and products will determine which direction of reaction is favoured by higher pressure.
- If the forward reaction produces more moles of gas than the back reaction then high pressure will reduce the amount of products formed.
- If the forward reaction produces less moles of gas than the back reaction then high pressure will increase the amount of products formed.
Hydrogen + Nitrogen ⇌ Ammonia
<chem> 3H2(g) + N2(g) <=> 2NH3(g) </chem>
- In this reversible reaction there are more moles of gas in the reactants than the products so higher pressure will favour the forward reaction and the equilibrium position will have a greater concentration of products than reactants.
Ammonium Chloride ⇌ Ammonia + Hydrochloric Acid
<chem> NH4Cl(s) <=> NH3(g) + HCl(g) </chem>
- In this reversible reaction there are more moles of gas in the products than the reactant so higher pressure will favour the back reaction and the equilibrium position will have a greater concentration of reactant than reactants.