Concentration and Temperature.  If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.  Stresses.

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Concentration and Temperature

 If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.  Stresses include: ◦ Change in concentration ◦ Change in volume/pressure ◦ Change in temperature

 PCl 5 (g) ⇆ PCl 3 (g) + Cl 2 (g) ΔH=-47kJ

 Volume and pressure are related. As the volume goes up the pressure goes down and vice versa.  (Boyles Law; P 1 V 1 =P 2 V 2 )  Only gases are affected by a change in volume/pressure  You need to count the number of moles on each side of the reaction

 2H 2 O (g) ⇆ 2 H 2 (g) + O 2 (g)  The left side has 2 molecules of gas, while the right side has 3 molecules of gas  If the stress is pressure increasing, shift toward the side with the least number of moles of gas.  If the stress is pressure decreasing, shift toward the side with the most number of moles of gas.

 Le Chatelier and Pressure - YouTube Le Chatelier and Pressure - YouTube

PCl 5(g) ⇆ PCl 3(g) + Cl 2(g)

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