Le Chatelier's Principle and Common Ion Effect - MCAT Chemical and Physical Foundations of Biological Systems
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Carbonic anhydrase is an important enzyme that allows CO2 and H2O to be converted into H2CO3. In addition to allowing CO2 to be dissolved into the blood and transported to the lungs for exhalation, the products of the carbonic anhydrase reaction, H2CO3 and a related compound HCO3-, also serve to control the pH of the blood to prevent acidosis or alkalosis. The carbonic anhydrase reaction and acid-base reaction are presented below.
CO2 + H2O 
H2CO3
H2CO3 
HCO3- + H+
While the kidney is able to compensate for many acid/base changes in our bodies, vomiting is a temporary cause of acid/base imbalance. While vomiting may allow our bodies to get rid of toxic substances, it also causes us to lose gastric acid, which influences blood pH. How would the loss of gastric acid change the pH of our blood?
Carbonic anhydrase is an important enzyme that allows CO2 and H2O to be converted into H2CO3. In addition to allowing CO2 to be dissolved into the blood and transported to the lungs for exhalation, the products of the carbonic anhydrase reaction, H2CO3 and a related compound HCO3-, also serve to control the pH of the blood to prevent acidosis or alkalosis. The carbonic anhydrase reaction and acid-base reaction are presented below.
CO2 + H2O
H2CO3
While the kidney is able to compensate for many acid/base changes in our bodies, vomiting is a temporary cause of acid/base imbalance. While vomiting may allow our bodies to get rid of toxic substances, it also causes us to lose gastric acid, which influences blood pH. How would the loss of gastric acid change the pH of our blood?
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This is an undercover Le Chatlier shift problem. The question tells us that vomiting causes us to lose gastric acid. In the equation that we can see above, losing H+ (in HCl) would pull the reaction to the right, increasing the concentration of HCO3-. Increasing the concentration of the base HCO3- increases the pH, leading the blood to become more basic.
This is an undercover Le Chatlier shift problem. The question tells us that vomiting causes us to lose gastric acid. In the equation that we can see above, losing H+ (in HCl) would pull the reaction to the right, increasing the concentration of HCO3-. Increasing the concentration of the base HCO3- increases the pH, leading the blood to become more basic.
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Carbonic anhydrase is an important enzyme that allows CO2 and H2O to be converted into H2CO3. In addition to allowing CO2 to be dissolved into the blood and transported to the lungs for exhalation, the products of the carbonic anhydrase reaction, H2CO3 and a related compound HCO3-, also serve to control the pH of the blood to prevent acidosis or alkalosis. The carbonic anhydrase reaction and acid-base reaction are presented below.
CO2 + H2O 
H2CO3
H2CO3 
HCO3- + H+
What happens to the pH of our blood if we hyperventilate?
Carbonic anhydrase is an important enzyme that allows CO2 and H2O to be converted into H2CO3. In addition to allowing CO2 to be dissolved into the blood and transported to the lungs for exhalation, the products of the carbonic anhydrase reaction, H2CO3 and a related compound HCO3-, also serve to control the pH of the blood to prevent acidosis or alkalosis. The carbonic anhydrase reaction and acid-base reaction are presented below.
CO2 + H2O
H2CO3
What happens to the pH of our blood if we hyperventilate?
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This is an undercover Le Chatlier shift problem. If we hyperventilate, we expel more CO2, thus pulling the reaction to the left and decreasing the concentration of H2CO3. As the concentration of the acid decreases, the blood becomes more basic, leading to respiratory alkalosis.
This is an undercover Le Chatlier shift problem. If we hyperventilate, we expel more CO2, thus pulling the reaction to the left and decreasing the concentration of H2CO3. As the concentration of the acid decreases, the blood becomes more basic, leading to respiratory alkalosis.
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If the reactants and/or products in a chemical reaction are gases, the reaction rate can be determined by measuring the change of pressure as the reaction proceeds. Consider the following reaction and pressure vs. reaction rate data below.
Trial PXY(torr) PZ(torr) Rate (torr/s) 1 100 200 0.16 2 200 200 0.32 3 200 100 0.04 4 200 150 0.14
If the volume of the container were reduced, what would happen to the rate of the reaction?
If the reactants and/or products in a chemical reaction are gases, the reaction rate can be determined by measuring the change of pressure as the reaction proceeds. Consider the following reaction and pressure vs. reaction rate data below.
| Trial | PXY(torr) | PZ(torr) | Rate (torr/s) |
|---|---|---|---|
| 1 | 100 | 200 | 0.16 |
| 2 | 200 | 200 | 0.32 |
| 3 | 200 | 100 | 0.04 |
| 4 | 200 | 150 | 0.14 |
If the volume of the container were reduced, what would happen to the rate of the reaction?
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Reducing the volume of the container increases pressure. This results in a higher frequency of gas particle collisions, thereby increasing the rate of the reaction.
Reducing the volume of the container increases pressure. This results in a higher frequency of gas particle collisions, thereby increasing the rate of the reaction.
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Consider the following equation for the production of ammonia gas from hydrogen gas and nitrogen gas.
If the volume of the vessel containing hydrogen and nitrogen is decreased, the production of ammonia .
Consider the following equation for the production of ammonia gas from hydrogen gas and nitrogen gas.
If the volume of the vessel containing hydrogen and nitrogen is decreased, the production of ammonia .
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Since decreasing the volume of the container has the effect of increasing pressure, equilibrium is shifted to the right. An increase in pressure has the result of favoring the side of the reaction with fewer moles of gas. (According to the balanced equation, there are 4 moles on the reactant side as opposed to 2 moles on the product side).
Since decreasing the volume of the container has the effect of increasing pressure, equilibrium is shifted to the right. An increase in pressure has the result of favoring the side of the reaction with fewer moles of gas. (According to the balanced equation, there are 4 moles on the reactant side as opposed to 2 moles on the product side).
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Le Chatlier's principle states that when a stressor is introduced to a system, the system will shift its equilibrium state as a way of countering the stress. What are the factors (stressors) that apply to Le Chatlier's principle?
Le Chatlier's principle states that when a stressor is introduced to a system, the system will shift its equilibrium state as a way of countering the stress. What are the factors (stressors) that apply to Le Chatlier's principle?
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Le Chatelier's principle emphasizes three main stressors: changes in temperature, pressure, and concentration of reactants and products. If any of these three stressors are added, the Keq will shift in a way that counters this added stress. Temperature and concentration changes will affect any reaction, while pressure changes will only have a marked effect on reactions involving at least one gaseous compound.
Le Chatelier's principle emphasizes three main stressors: changes in temperature, pressure, and concentration of reactants and products. If any of these three stressors are added, the Keq will shift in a way that counters this added stress. Temperature and concentration changes will affect any reaction, while pressure changes will only have a marked effect on reactions involving at least one gaseous compound.
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Consider the following saturated solution. Assume it is at equilibrium.
Adding sodium chromate to the above solution would the solubility of lead chromate due to .
Consider the following saturated solution. Assume it is at equilibrium.
Adding sodium chromate to the above solution would the solubility of lead chromate due to .
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Adding sodium chromate increases the concentration of chromate ion in the solution, which shifts the reaction to the left due to the common ion effect. Thus, the solubility of lead chromate would decrease, as there would be an increased amount of solid lead chromate.
Adding sodium chromate increases the concentration of chromate ion in the solution, which shifts the reaction to the left due to the common ion effect. Thus, the solubility of lead chromate would decrease, as there would be an increased amount of solid lead chromate.
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Consider the reaction reaction below.
A student allows the system to reach equilibrium and then removes two moles of hydrogen gas. Which of the following will be a result?
Consider the reaction reaction below.
A student allows the system to reach equilibrium and then removes two moles of hydrogen gas. Which of the following will be a result?
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According to Le Chatelier's principle, when a system at equilibrium is disturbed, the system will react to restore equilibrium. In other words, it will seek to undo the stress. Here, if hydrogen gas is removed, the reaction will shift toward the reactants to re-form it. In the process, more nitrogen will be produced.
According to Le Chatelier's principle, when a system at equilibrium is disturbed, the system will react to restore equilibrium. In other words, it will seek to undo the stress. Here, if hydrogen gas is removed, the reaction will shift toward the reactants to re-form it. In the process, more nitrogen will be produced.
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The Haber process for creating ammonia is written below.
This reaction takes place in a glass container, and is allowed to progress to equilibrium. Which of the following manipulations to the system will NOT shift the equilibrium to the left?
The Haber process for creating ammonia is written below.
This reaction takes place in a glass container, and is allowed to progress to equilibrium. Which of the following manipulations to the system will NOT shift the equilibrium to the left?
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Le Chatlier's principle states that when a system at equilibrium is stressed, the equilibrium will shift accordingly in order to reduce the stress. There are a variety of ways to stress the system and elicit a shift.
-
Addition or removal of a reactant or product.
-
Changing the pressure of a system containing gases.
-
Changing the temperature of the system.
By increasing the pressure of the system, the reaction will shift in the direction which results in fewer gas molecules in the container. Since there are only two gas molecules on the product side and four gas molecules on the reactant side, we would predict a pressure increase to shift the equilibrium to the right.
Increasing temperature and adding ammonia both equate to adding product, which will shift the reaction away from the products and toward the reactants. Similarly, removing a reactant, such as nitrogen, will cause more of that reactant to be produced, also shifting the reaction to the left.
Le Chatlier's principle states that when a system at equilibrium is stressed, the equilibrium will shift accordingly in order to reduce the stress. There are a variety of ways to stress the system and elicit a shift.
-
Addition or removal of a reactant or product.
-
Changing the pressure of a system containing gases.
-
Changing the temperature of the system.
By increasing the pressure of the system, the reaction will shift in the direction which results in fewer gas molecules in the container. Since there are only two gas molecules on the product side and four gas molecules on the reactant side, we would predict a pressure increase to shift the equilibrium to the right.
Increasing temperature and adding ammonia both equate to adding product, which will shift the reaction away from the products and toward the reactants. Similarly, removing a reactant, such as nitrogen, will cause more of that reactant to be produced, also shifting the reaction to the left.
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Barium fluoride dissolves in solution according to the following equation.
Enough BaF2 is added to create a saturated liter of aqueous solution.
Suppose that 1M NaF is added to the solution, such that it does not change the volume of the solution. What would you expect to change as a result of the addition of NaF?
Barium fluoride dissolves in solution according to the following equation.
Enough BaF2 is added to create a saturated liter of aqueous solution.
Suppose that 1M NaF is added to the solution, such that it does not change the volume of the solution. What would you expect to change as a result of the addition of NaF?
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By adding NaF to the equation, 1M of F- ions are added to the solution. Thinking in terms of Le Chatlier's principle, the addition of a compound on one side of the equation will cause a shift to the other side of the reaction.
It DOES NOT affect the solubility product constant. Since there is an addition to the products side of the reaction, there will be a shift to the left, and more salt (reactant) will be precipitated. As a result, the solubility of the salt has decreased, because of the addition of NaF. This is known as the common ion effect.
By adding NaF to the equation, 1M of F- ions are added to the solution. Thinking in terms of Le Chatlier's principle, the addition of a compound on one side of the equation will cause a shift to the other side of the reaction.
It DOES NOT affect the solubility product constant. Since there is an addition to the products side of the reaction, there will be a shift to the left, and more salt (reactant) will be precipitated. As a result, the solubility of the salt has decreased, because of the addition of NaF. This is known as the common ion effect.
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Barium fluoride dissolves in solution according to the following equation.
Enough BaF2 is added to create a saturated liter of aqueous solution.
Suppose you double the amount of salt in the saturated solution. What would happen as a result of adding more BaF2?
Barium fluoride dissolves in solution according to the following equation.
Enough BaF2 is added to create a saturated liter of aqueous solution.
Suppose you double the amount of salt in the saturated solution. What would happen as a result of adding more BaF2?
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Remember that the concentration of the salt is not included in the solubility product constant equation, because it is a solid. Only the ion concentrations can affect the solubility of the salt in solution. When the solution is saturated, adding more salt will do nothing to the concentration of ions in the solution.
Remember that the concentration of the salt is not included in the solubility product constant equation, because it is a solid. Only the ion concentrations can affect the solubility of the salt in solution. When the solution is saturated, adding more salt will do nothing to the concentration of ions in the solution.
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A saturated solution of scandium hydroxide, which also contains solid scandium hydroxide, is treated with 0.1N HCl. The addition of acid will the solubility of scandium hydroxide because of .
A saturated solution of scandium hydroxide, which also contains solid scandium hydroxide, is treated with 0.1N HCl. The addition of acid will the solubility of scandium hydroxide because of .
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Scandium hydroxide dissociates according to this reaction.
As 0.1N HCl is added, it will quantitatively react with hydroxide anions to produce ScCl3 and water.
Hydroxide will be removed from the above equilibrium, and the system will compensate by shifting the equilibrium to the right, according Le Chatelier's principle. As the equilibrium shifts to the right, more solid scandium hydroxide is hydrolyzed, resulting in increased solubility.
Scandium hydroxide dissociates according to this reaction.
As 0.1N HCl is added, it will quantitatively react with hydroxide anions to produce ScCl3 and water.
Hydroxide will be removed from the above equilibrium, and the system will compensate by shifting the equilibrium to the right, according Le Chatelier's principle. As the equilibrium shifts to the right, more solid scandium hydroxide is hydrolyzed, resulting in increased solubility.
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Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
In studying the acid 
, a scientist finds that heat is released when the acid dissociates in solution. If this scientist raises the temperature in the vessel after the reaction has reached equilibrium, which of the following is most likely true?
Acids and bases can be described in three principal ways. The Arrhenius definition is the most restrictive. It limits acids and bases to species that donate protons and hydroxide ions in solution, respectively. Examples of such acids include HCl and HBr, while KOH and NaOH are examples of bases. When in aqueous solution, these acids proceed to an equilibrium state through a dissociation reaction.
All of the bases proceed in a similar fashion.
The Brønsted-Lowry definition of an acid is a more inclusive approach. All Arrhenius acids and bases are also Brønsted-Lowry acids and bases, but the converse is not true. Brønsted-Lowry acids still reach equilibrium through the same dissociation reaction as Arrhenius acids, but the acid character is defined by different parameters. The Brønsted-Lowry definition considers bases to be hydroxide donors, like the Arrhenius definition, but also includes conjugate bases such as the A- in the above reaction. In the reverse reaction, A- accepts the proton to regenerate HA. The Brønsted-Lowry definition thus defines bases as proton acceptors, and acids as proton donors.
In studying the acid
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In exothermic process heat is released during the reaction.
Heat can be considered a product in this situation, and thus increasing the amount of heat in the vessel after the system has reached equilibrium will drive the reaction to the left. This property is a derivative of Le Chatelier's principle.
In exothermic process heat is released during the reaction.
Heat can be considered a product in this situation, and thus increasing the amount of heat in the vessel after the system has reached equilibrium will drive the reaction to the left. This property is a derivative of Le Chatelier's principle.
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A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
The scientist in the passage attempts to modify the conditions for the reactions by placing the reactants in a sealed, variable-volume vessel at 1atm, and allowing it to reach equilibrium. She then decreases the volume of the vessel, increasing the pressure to 5atm. Which of the following is most likely to occur?
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
The scientist in the passage attempts to modify the conditions for the reactions by placing the reactants in a sealed, variable-volume vessel at 1atm, and allowing it to reach equilibrium. She then decreases the volume of the vessel, increasing the pressure to 5atm. Which of the following is most likely to occur?
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By changing the volume of the container, the scientist has changed the partial pressure of nitrogen gas in the vessel. As a result, the equilibrium shifts to the left, increasing the concentration of the reactants.
According to Le Chatelier's principle, decreasing pressure will shift equilibrium away from any gaseous compounds. The only gas in the reaction is the nitrogen product. Decreasing volume will, thus, shift equilibrium toward the reactants.
By changing the volume of the container, the scientist has changed the partial pressure of nitrogen gas in the vessel. As a result, the equilibrium shifts to the left, increasing the concentration of the reactants.
According to Le Chatelier's principle, decreasing pressure will shift equilibrium away from any gaseous compounds. The only gas in the reaction is the nitrogen product. Decreasing volume will, thus, shift equilibrium toward the reactants.
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A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
The scientist in the passage attempts to modify the conditions for the reaction by placing the reactants in a sealed vessel at 1atm, and allowing it to reach equilibrium. She then adds helium gas to the vessel, increasing the pressure to 5atm. Which of the following is most likely to occur?
A scientist is studying a reaction, and places the reactants in a beaker at room temperature. The reaction progresses, and she analyzes the products via NMR. Based on the NMR readout, she determines the reaction proceeds as follows:
In an attempt to better understand the reaction process, she varies the concentrations of the reactants and studies how the rate of the reaction changes. The table below shows the reaction concentrations as she makes modifications in three experimental trials.
The scientist in the passage attempts to modify the conditions for the reaction by placing the reactants in a sealed vessel at 1atm, and allowing it to reach equilibrium. She then adds helium gas to the vessel, increasing the pressure to 5atm. Which of the following is most likely to occur?
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The addition of an inert gas like helium does not change the partial pressure of the products or reactants. As a result, the equilibrium concentrations do not change.
The addition of an inert gas like helium does not change the partial pressure of the products or reactants. As a result, the equilibrium concentrations do not change.
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In the given reaction, which of the following changes takes place if the temperature of the system is increased?
In the given reaction, which of the following changes takes place if the temperature of the system is increased?
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This reaction is exothermic, since heat is released in the reaction. In exothermic reactions, decreasing the temperature favors the forward (exothermic) reaction, while increasing the temperature favors the reverse (endothermic) reaction. Similarly, for an endothermic reaction decreasing the temperature favors the reverse (exothermic) reaction, while increasing the temperature favors the forwards (endothermic) reaction.
In this question, increasing the temperature will favor the reverse reaction, increasing the reactant concentration and decreasing the product concentration.
This reaction is exothermic, since heat is released in the reaction. In exothermic reactions, decreasing the temperature favors the forward (exothermic) reaction, while increasing the temperature favors the reverse (endothermic) reaction. Similarly, for an endothermic reaction decreasing the temperature favors the reverse (exothermic) reaction, while increasing the temperature favors the forwards (endothermic) reaction.
In this question, increasing the temperature will favor the reverse reaction, increasing the reactant concentration and decreasing the product concentration.
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This reaction is allowed to proceed to equilibrium in a 
container. Which of the following results will occur if the volume is suddenly decreased to 
?
This reaction is allowed to proceed to equilibrium in a
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This reaction is at equilibrium until it is disturbed by a sudden volume change. Since the volume is decreased, the pressure on the container's contents will increase. According to Le Chatelier's principle, an increase in pressure will cause the reaction to shift toward the side that contains fewer gas particles.
In this reaction, there are three moles of gas in the reactants and two moles of gas in the products. A decrease in volume, or increase in pressure, will shift the reaction to the right, toward the product 
.
This reaction is at equilibrium until it is disturbed by a sudden volume change. Since the volume is decreased, the pressure on the container's contents will increase. According to Le Chatelier's principle, an increase in pressure will cause the reaction to shift toward the side that contains fewer gas particles.
In this reaction, there are three moles of gas in the reactants and two moles of gas in the products. A decrease in volume, or increase in pressure, will shift the reaction to the right, toward the product
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A system contains iodine atoms that are in equilibrium with respect to the reaction below:
The volume of the system is suddenly reduced, leading to an increase in pressure. What effect will this have on the reaction?
A system contains iodine atoms that are in equilibrium with respect to the reaction below:
The volume of the system is suddenly reduced, leading to an increase in pressure. What effect will this have on the reaction?
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Since the system is originally at equilibrium and a stress is applied, Le Chatelier's principle is to be considered. By increasing the total pressure, the reaction will move in the direction toward which there are less molecules of gas.
Looking at the original reaction there are two moles of gas on the left and only one on the right, indicating that the reaction will shift to the right if the pressure is increased.
Since the system is originally at equilibrium and a stress is applied, Le Chatelier's principle is to be considered. By increasing the total pressure, the reaction will move in the direction toward which there are less molecules of gas.
Looking at the original reaction there are two moles of gas on the left and only one on the right, indicating that the reaction will shift to the right if the pressure is increased.
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The Haber-Bosch process, or simply the Haber process, is a common industrial reaction that generates ammonia from nitrogen and hydrogen gas. A worker in a company generates ammonia from the Haber process. He then dissociates the gaseous ammonia in water to produce an aqueous solution. Since ammonia is a base, it will accept a proton from water, generating 
and ammonium ion products. The two reactions involved are:
The worker could do which of the following to shift the equilibrium towards hydroxide (
) ions?
I. Add hydrogen gas
II. Add 
III. Add 
The Haber-Bosch process, or simply the Haber process, is a common industrial reaction that generates ammonia from nitrogen and hydrogen gas. A worker in a company generates ammonia from the Haber process. He then dissociates the gaseous ammonia in water to produce an aqueous solution. Since ammonia is a base, it will accept a proton from water, generating
The worker could do which of the following to shift the equilibrium towards hydroxide (
I. Add hydrogen gas
II. Add
III. Add
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You need to understand Le Chatelier’s principle to solve this question. Le Chatelier’s principle states that the addition of excess molecules to one side of a reaction will shift the equilibrium toward the other side. This shift makes sure that the reaction remains at equilibrium.
If you add hydrogen gas, reaction 1 will shift to the right and will produce more ammonia. Since more ammonia is produced, reaction 2 will shift to the right to produce more ammonium ions and hydroxide ions. Statement I is correct.
Adding 
to the solution will increase the concentration of hydroxide ions. This means that the equilibrium of reaction 2 will shift to the left, away from hydroxide ions. While the overall hydroxide ion concentration may increase due to the addition of the base, the equilibrium for the reaction will shift away from the hydroxide ions, making statement II incorrect.
Finally, adding 
will generate 
ions. These 
ions will react with the 
ions and form water, which will decrease the overall concentration of hydroxide ions. The equilibrium of reaction 2 will shift to the right to produce more ammonium and hydroxide ions. Statement III is correct.
You need to understand Le Chatelier’s principle to solve this question. Le Chatelier’s principle states that the addition of excess molecules to one side of a reaction will shift the equilibrium toward the other side. This shift makes sure that the reaction remains at equilibrium.
If you add hydrogen gas, reaction 1 will shift to the right and will produce more ammonia. Since more ammonia is produced, reaction 2 will shift to the right to produce more ammonium ions and hydroxide ions. Statement I is correct.
Adding
Finally, adding
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The Haber-Bosch process, or simply the Haber process, is a common industrial reaction that generates ammonia from nitrogen and hydrogen gas. A worker in a company generates ammonia from the Haber process. He then dissociates the gaseous ammonia in water to produce an aqueous solution. Since ammonia is a base, it will accept a proton from water, generating and ammonium ion products. The two reactions involved are:
What will happen if the worker increases the pH?
The Haber-Bosch process, or simply the Haber process, is a common industrial reaction that generates ammonia from nitrogen and hydrogen gas. A worker in a company generates ammonia from the Haber process. He then dissociates the gaseous ammonia in water to produce an aqueous solution. Since ammonia is a base, it will accept a proton from water, generating
What will happen if the worker increases the pH?
Tap to reveal answer
Increasing the pH is equivalent to decreasing hydrogen ion concentration or increasing hydroxide ion concentration. This increase in hydroxide ion concentration will shift the equilibrium of reaction 2 to the left, producing more ammonia. This is a fundamental point of Le Chatelier's principle.
Increasing the pH is equivalent to decreasing hydrogen ion concentration or increasing hydroxide ion concentration. This increase in hydroxide ion concentration will shift the equilibrium of reaction 2 to the left, producing more ammonia. This is a fundamental point of Le Chatelier's principle.
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Two solutions of the same ionic compound are prepared. One solution uses a pure water solvent, while the other uses a solution of dilute sodium chloride. Equal amounts of the ionic compound are added to each solvent. A student observes that a precipitate forms in the solution that used brine as a solvent, but not in the aqueous solution.
What is the most likely cause of this phenomenon?
Two solutions of the same ionic compound are prepared. One solution uses a pure water solvent, while the other uses a solution of dilute sodium chloride. Equal amounts of the ionic compound are added to each solvent. A student observes that a precipitate forms in the solution that used brine as a solvent, but not in the aqueous solution.
What is the most likely cause of this phenomenon?
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This phenomenon is called the common-ion effect. When a compound dissolves in water it dissociates into ions. Increasing the concentration of one of these ions will shift the equilibrium towards the compound, thereby making it hard for the compound to dissolve in water (decreases solubility of compound). The ionic compound may have been something like silver chloride, which has a low solubility in water. A small amount may dissolve in aqueous solution, but the preexistence of chloride ions in the solvent would reduce the already low solubility and generate a precipitate.
Increasing chloride ion concentration shifts equilibrium to the left. While this phenomenon is directly linked to Le Chatelier's principle, the direct term is the common-ion effect.
A dissociation reaction does occur, but that does not explain the formation of the precipitate in only one solution. Also, since equal amounts of the ionic compounds are added to each solvent, we cannot make any conclusions about saturation.
This phenomenon is called the common-ion effect. When a compound dissolves in water it dissociates into ions. Increasing the concentration of one of these ions will shift the equilibrium towards the compound, thereby making it hard for the compound to dissolve in water (decreases solubility of compound). The ionic compound may have been something like silver chloride, which has a low solubility in water. A small amount may dissolve in aqueous solution, but the preexistence of chloride ions in the solvent would reduce the already low solubility and generate a precipitate.
Increasing chloride ion concentration shifts equilibrium to the left. While this phenomenon is directly linked to Le Chatelier's principle, the direct term is the common-ion effect.
A dissociation reaction does occur, but that does not explain the formation of the precipitate in only one solution. Also, since equal amounts of the ionic compounds are added to each solvent, we cannot make any conclusions about saturation.
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