For the following equilibrium system, which of the changes will form more CaCO3 (more moles CaCO3)?
CO2 + Ca(OH)2=CaCO3 +H2O delta H =-113kJ
Write and explain if amount CaCO3 decrease, no change or increase with regards to the following situations:
a) Decrease temperature at constant pressure (no phase change).
b) Increase volume at constant temperature.
c)Increase partial pressure of CO2.
d)Remove one-half of the initial CaCO3.
Le Chatelier's Principle says, in simple terms, that a system in equilibrium will try to undo what we do to it.
a) The reaction is exothermic meaning it releases heat; therefore, if we decrease temperature (decrease the heat to it) the reaction will respond by trying to increase it. If it goes forward (to the right) that increases it. If it goes to the left it uses up heat. If it does neither, nothing happens. (Those are the only three choices you have.) So it must be obvious that decreasing T means it will shift to the right.
To determine the effect of each change on the formation of more CaCO3 in the given equilibrium system, let's analyze each situation:
a) Decrease in temperature at constant pressure (no phase change):
To understand the impact of temperature change on the equilibrium, we need to consider the sign of the delta H value (-113 kJ). This value represents the heat released during the forward reaction (formation of CaCO3). Since the delta H value is negative, it means the reaction is exothermic, i.e., heat is released during the formation of CaCO3.
Decreasing the temperature will shift the equilibrium towards the exothermic side to compensate for the loss of heat. In this case, the backward reaction (decomposition of CaCO3) will be favored, resulting in a decrease in the amount of CaCO3 formed.
Therefore, the amount of CaCO3 will decrease when the temperature is decreased at a constant pressure.
b) Increase in volume at constant temperature:
When the volume of the system is increased at constant temperature, the pressure will decrease. To evaluate the effect on the formation of CaCO3, we need to examine the stoichiometry of the balanced equation.
In the given equilibrium system, there are equal numbers of moles of gaseous molecules on both sides of the reaction equation. Therefore, changing the volume or pressure will not have a significant impact on the equilibrium position. It means the amount of CaCO3 formed will remain unchanged.
c) Increase in partial pressure of CO2:
Increasing the partial pressure of CO2 means adding more CO2 to the system. To determine the effect on CaCO3 formation, we need to consider Le Chatelier's principle, which states that a system at equilibrium will respond to a stress by shifting the equilibrium to counteract the stress.
In this case, increasing the partial pressure of CO2 will cause the equilibrium to shift in the forward direction, favoring the formation of more CaCO3 to offset the increased concentration of CO2. Consequently, the amount of CaCO3 formed will increase.
d) Removal of one-half of the initial CaCO3:
Removing one-half of the initial CaCO3 will disrupt the equilibrium. According to Le Chatelier's principle, the system will respond by shifting the equilibrium in the forward direction to compensate for the loss of CaCO3. Therefore, more CaCO3 will be formed to restore the balance, resulting in an increase in the amount of CaCO3.
To summarize the effects of the changes on the amount of CaCO3:
a) Decrease in temperature: Decrease CaCO3.
b) Increase in volume: No change in CaCO3.
c) Increase in partial pressure of CO2: Increase CaCO3.
d) Removal of one-half of the initial CaCO3: Increase CaCO3.