LeChatelier's Principle  page 2  GO BACK TO THE CHEMISTRY DRILLS PAGE     +

What happens when stress is added to a chemical reaction?

Below are 2 different chemical reactions, with a variety of stresses that could be added to them.
Click each stress to see which way the dynamic equilibrium will shift (temporarily) until a new
dynamic equilibrium will be set under the new conditions caused by the stress.  

2H2(G)  +  O2(G)   2H2O(G)  + energy	2Al2O3(G)  + energy    4Al(S)  +  3 O2(G)
add energy/heat add hydrogen gas add oxygen gas add water gas increase pressure remove hydrogen remove oxygen gas remove energy/heat remove water gas decrease pressure	add Al2O3 increase temperature add Al add O2 increase the pressure remove Al2O3 decrease temperature remove Al remove O2 decrease the pressure

add energy/heat

<---- shift reverse

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

energy or heat will allow for more decomposition to occur.

until a new dynamic equilibrium is reached.  

add hydrogen gas

shift forward ---->  

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

Extra hydrogen will cause more collisions between hydrogen and oxgyen which will create more synthesis

until a new dynamic equilibrium is reached.  

add oxygen gas

shift forward ----> 

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

extra oxygen will allow for more collisions between oxygen and hydrogen, causing more synthesis.

until a new dynamic equilibrium is reached.  

add water gas

<---- shift reverse

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

extra water will allow for more decomposition to occur.

until a new dynamic equilibrium is reached.  

increase pressure

shift forward ---->  

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

More pressure will make reaction favor the side with less moles of gas, three to the left, shift to the right with just 2 moles of gas.

until a new dynamic equilibrium is reached.  

remove hydrogen

<---- shift reverse

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

Less hydrogen will lessen synthesis by lowering collisions between hydrogen and oxgyen.

until a new dynamic equilibrium is reached.  

remove oxygen gas

<---- shift reverse

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

Less oxygen will lessen the synthesis by lowering the number of collisions between oxygen and hydrogen.

until a new dynamic equilibrium is reached.  

remove energy/heat

shift forward ---->  

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

With less energy or temperature, there will be less decomposition (which means more synthesis). 

until a new dynamic equilibrium is reached.  

remove water gas

shift forward ---->  

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

With less water, there will be less decomposition (which means more synthesis). 

until a new dynamic equilibrium is reached.  

decrease pressure

<---- shift reverse

2H_2(G)  +  O_2(G)   2H₂O_(G)  + energy

With less pressure, there will be a shift towards the side with more moles of gas, which means to the left, or reverse.

until a new dynamic equilibrium is reached.  

add Al₂O₃

shift forward ---->  

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With more aluminum oxide, there will be more decomposition. 

until a new dynamic equilibrium is reached.  

increase temperature

shift forward ---->  

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With more energy or temperature, there will be more decomposition possible. 

until a new dynamic equilibrium is reached.  

add Al

<---- shift reverse

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With more aluminum, there will be more collisions between aluminum and oxygen (which means more synthesis). 

until a new dynamic equilibrium is reached.  

add O₂

<---- shift reverse

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With more oxygen, there will be more collisions between aluminum & oxygen (which means more synthesis). 

until a new dynamic equilibrium is reached.  

increase the pressure

<---- shift reverse

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With more pressure there will be a shift towards the side with less moles of gas, which is the left side. 

until a new dynamic equilibrium is reached.  

remove Al₂O₃

<---- shift reverse

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With less Al₂O₃ there will be less synthesis, so more decomposition will occur. 

until a new dynamic equilibrium is reached.  

decrease temperature

<---- shift reverse

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With less temperature or energy, there will be less decomposition possible, so more synthesis occurs. 

until a new dynamic equilibrium is reached.  

remove Al

shift forward ---->  

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With less aluminum, there will be less collisions between aluminum & oxygen (which means less synthesis or more decomposition). 

until a new dynamic equilibrium is reached.  

remove O₂

shift forward ---->  

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With less oxygen, there will be less collisions between aluminum and oxygen (which means less synthesis - or more decomposition). 

until a new dynamic equilibrium is reached.  

decrease the pressure

shift forward ---->  

2Al₂O_3(G)  + energy    4Al_(S)  +  3 O_2(G)

With less pressure, there will be a shift towards the side with the greater number of moles of gas, or forward.

until a new dynamic equilibrium is reached. 

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