Predict the effect of each of the following on the indicated equilibrium system in terms of which reaction will be favored (forward, reverse, or neither)
H2(g)+Cl2(g)<=>2HCl(g) +184 kJ
A)addition of Cl2
B)removal of HCl
C)increased pressure
D)decreased temperature
E)removal of H2
F)decreased pressure
G)addition of a catalyst
H)increased temperature
I)decreased system volume
A) Addition of Cl2: According to Le Chatelier's principle, when you add a reactant, the equilibrium will shift to the right to consume the added substance. Therefore, the forward reaction (formation of HCl) will be favored.
B) Removal of HCl: If you remove a product, the equilibrium will shift to replace the lost substance. In this case, the reverse reaction (HCl decomposition) will be favored to replenish the removed HCl.
C) Increased pressure: When pressure is increased, the system will try to reduce the pressure by favoring the reaction that produces fewer moles of gas. In this case, the forward reaction (formation of HCl) is favored since it reduces the number of gas molecules.
D) Decreased temperature: Lowering the temperature favors the exothermic reaction to generate heat. Since the forward reaction is exothermic, it will be favored at lower temperature.
E) Removal of H2: Removing a reactant will cause the equilibrium to shift in the direction that replaces it. Consequently, the reverse reaction (HCl decomposition) will be favored to replenish the lost H2.
F) Decreased pressure: When the pressure is decreased, the system will favor the reaction that produces more moles of gas. In this case, the reverse reaction (HCl decomposition) creates more moles of gas and will be favored.
G) Addition of a catalyst: A catalyst does not affect the position of equilibrium. It only speeds up the rate at which equilibrium is reached. Therefore, the addition of a catalyst will not favor any specific reaction.
H) Increased temperature: As the temperature increases, the equilibrium will shift in the direction that absorbs heat. Since the forward reaction is exothermic, it will be favored at higher temperatures.
I) Decreased system volume: Decreasing the volume increases the pressure on the system. In response, the equilibrium will shift to reduce pressure, favoring the reaction that produces fewer moles of gas. In this case, the forward reaction (formation of HCl) will be favored.
To predict the effect of each scenario on the equilibrium system, we need to apply Le Chatelier's principle. This principle states that if a change is applied to a system at equilibrium, the system will respond in a way to counteract or minimize that change.
Let's analyze each scenario one by one:
A) Addition of Cl2:
By adding Cl2, we are increasing the concentration of Cl2 in the system. According to Le Chatelier's principle, the system will try to minimize the increase in Cl2 concentration. It will do so by favoring the forward reaction to use up some of the excess Cl2. Therefore, adding Cl2 will favor the forward reaction.
B) Removal of HCl:
By removing HCl, we are decreasing its concentration in the system. To counteract this decrease, the system will shift in the reverse direction to produce more HCl. Thus, removing HCl will favor the reverse reaction.
C) Increased pressure:
Increasing the pressure of a gaseous equilibrium system will cause the system to shift in the direction that reduces the number of moles of gas. In this case, since the forward reaction produces two moles of gas (2HCl), while the reverse reaction consumes three moles of gas (H2 + Cl2), increasing the pressure will favor the formation of fewer moles of gas. Therefore, increased pressure will favor the reverse reaction.
D) Decreased temperature:
Decreasing the temperature of an exothermic reaction will shift the equilibrium in the exothermic direction to counteract the reduction in heat. The forward reaction is exothermic, meaning it releases heat. Therefore, decreasing the temperature would favor the forward reaction.
E) Removal of H2:
When H2 is removed from the system, Le Chatelier's principle states that the system will respond by favoring the production of H2. Thus, the equilibrium will shift in the forward direction.
F) Decreased pressure:
Decreasing the pressure of a gaseous equilibrium system will cause the system to shift in the direction that increases the number of moles of gas. In this case, decreasing the pressure will favor the side with more moles of gas, which is the forward reaction. Therefore, decreased pressure will favor the forward reaction.
G) Addition of a catalyst:
A catalyst does not affect the position of equilibrium. It increases the rate of both the forward and reverse reactions equally. Therefore, the addition of a catalyst does not favor any specific reaction.
H) Increased temperature:
Increasing the temperature of an exothermic reaction will shift the equilibrium in the endothermic direction to counteract the increase in heat. The forward reaction is exothermic. Thus, increasing the temperature would favor the reverse reaction, which is the endothermic direction.
I) Decreased system volume:
When the system volume is decreased, the pressure increases. As discussed before, an increase in pressure favors the side of the reaction with fewer gas moles. In this case, the forward reaction has more moles of gas. Therefore, reducing the system volume will favor the forward reaction.
It's important to note that Le Chatelier's principle provides a qualitative understanding of how equilibrium systems respond to changes. The direction of the shift may not necessarily be absolute, and the extent of the shift can depend on factors such as reaction kinetics, concentrations, and temperature.