LeChatelier's Principle   +      GO BACK TO 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. 

Energy + H2(G)  +  I2(G)   2HI(G)	C(S)  +  O2(G)   CO2(G)  + energy
add energy/heat add HI gas add iodine gas increase pressure add hydrogen gas remove hydrogen remove iodine gas remove energy/heat remove HI gas decrease pressure	add heat/energy add carbon add oxygen gas increase the pressure add carbon dioxide gas remove carbon remove oxygen gas remove heat/energy remove carbon dioxide gas decrease the pressure

add energy/heat

shift forward ---->  

Energy + H_2(G)  +  I_2(G)   2HI_(G)

more energy will cause more synthesis
resulting in more HI gas production

(until a new dynamic equilibrium is reached)

add HI gas

<---- shift reverse

Energy + H_2(G)  +  I_2(G)   2HI_(G)

more HI gas will cause more decomposition

(until a new dynamic equilibrium is reached)

add iodine gas

shift forward ---->  

Energy + H_2(G)  +  I_2(G)   2HI_(G)

more iodine gas will result in more HI gas production

(until a new dynamic equilibrium is reached)

increase pressure

no changes

Energy + H_2(G)  +  I_2(G)   2HI_(G)

the same number of moles of gas exist on both sides of the double arrow, both sides equally affected by increase, or decrease in pressure.

add hydrogen gas

shift forward ---->  

Energy + H_2(G)  +  I_2(G)   2HI_(G)

more hydrogen will result in more HI gas production

(until a new dynamic equilibrium is reached)

remove hydrogen

<---- shift reverse

Energy + H_2(G)  +  I_2(G)   2HI_(G)

Less hydrogen gas will slow production of HI gas, 
more decomposition will result

(until a new dynamic equilibrium is reached)

remove iodine gas

<---- shift reverse

Energy + H_2(G)  +  I_2(G)   2HI_(G)

Less iodine gas will slow production of HI gas, 
more decomposition will result

(until a new dynamic equilibrium is reached)

remove energy/heat

<---- shift reverse

Energy + H_2(G)  +  I_2(G)   2HI_(G)

Less energy will slow forward reaction/synthesis which requires energy, more decomposition will occur

(until a new dynamic equilibrium is reached)

remove HI gas

shift forward ---->  

Energy + H_2(G)  +  I_2(G)   2HI_(G)

removal of HI gas will slow decomposition, more HI keeps forming to get a new balance

(until a new dynamic equilibrium is reached)

decrease pressure

no changes

Energy + H_2(G)  +  I_2(G)   2HI_(G)

the same number of moles of gas exist on both sides of the double arrow, both sides equally affected by decrease, or increase in pressure.

add heat/energy

<---- shift reverse

C_(S)  +  O_2(G)   CO_2(G)  + energy

more energy will cause more decomposition

(until a new dynamic equilibrium is reached)

add carbon

shift forward ----> 

C_(S)  +  O_2(G)   CO_2(G)  + energy

adding more carbon will cause more collision with oxygen, making more carbon dioxide gas

(until a new dynamic equilibrium is reached)

add oxygen gas

shift forward ----> 

C_(S)  +  O_2(G)   CO_2(G)  + energy

adding more oxygen will cause more collision with carbon, making more carbon dioxide gas

(until a new dynamic equilibrium is reached)

increase the pressure

no changes

C_(S)  +  O_2(G)   CO_2(G)  + energy

the same number of moles of gas exist on both sides of the double arrow, both sides equally affected by decrease, or increase in pressure.

add carbon dioxide gas

<---- shift reverse

C_(S)  +  O_2(G)   CO_2(G)  + energy

more carbon dioxide will result in more decomposition

(until a new dynamic equilibrium is reached)

remove carbon

<---- shift reverse

C_(S)  +  O_2(G)   CO_2(G)  + energy

Less carbon will allow for less synthesis of carbon dioxide, more decomposition will occur

(until a new dynamic equilibrium is reached)

remove oxygen gas

<---- shift reverse

C_(S)  +  O_2(G)   CO_2(G)  + energy

with less oxygen there will be less synthesis, so more decomposition will occur

(until a new dynamic equilibrium is reached)

remove heat/energy

shift forward ---->

C_(S)  +  O_2(G)   CO_2(G)  + energy

removing heat or energy will allow for more synthesis

(until a new dynamic equilibrium is reached)

remove carbon dioxide gas

shift forward ----> 

C_(S)  +  O_2(G)   CO_2(G)  + energy

with less CO₂, there will be less decomposition,

balance shifts to making more carbon dioxide

(until a new dynamic equilibrium is reached)

decrease the pressure

C_(S)  +  O_2(G)   CO_2(G)  + energy

no changes

the same number of moles of gas exist on both sides of the double arrow, both sides equally affected by decrease, or increase in pressure.