Chemistry Ch18&19 Exam
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The law of chemical equilibrium states that at a given pressure, a chemical system may reach a state in which a particular ratio of reactant to product concentrations has a constant value.
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True
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False
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This Chemistry Ch18&19 Exam assesses understanding of chemical equilibrium concepts, including the law of chemical equilibrium, equilibrium constants, and reaction favorability. It tests critical thinking and application of theoretical knowledge in practical scenarios.
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True
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False
Correct Answer
A. True -
- 3.
If an equilibrium constant has a value less than one, the reactants are favored at equilibrium.
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True
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False
Correct Answer
A. TrueExplanation
If an equilibrium constant has a value less than one, it indicates that the concentration of products at equilibrium is lower than the concentration of reactants. This means that the reaction is more likely to favor the reactants and proceed in the reverse direction. Therefore, the statement "the reactants are favored at equilibrium" is true in this case.Rate this question:
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- 4.
The value for Keq is constant only at a specific volume.
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True
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False
Correct Answer
A. FalseExplanation
The statement that "The value for Keq is constant only at a specific volume" is false. The value for Keq, which represents the equilibrium constant, is actually constant at a specific temperature, not volume. The equilibrium constant is a ratio of the concentrations of products to reactants at equilibrium, and it remains constant as long as the temperature is constant. Changes in volume do not affect the equilibrium constant, although they may shift the position of the equilibrium.Rate this question:
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- 5.
In an exothermic reaction, an increase in temperature favors the formation of products
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True
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False
Correct Answer
A. FalseExplanation
In an exothermic reaction, the reaction releases heat energy to the surroundings. Therefore, an increase in temperature would shift the equilibrium towards the reactants, favoring the reverse reaction rather than the formation of products.Rate this question:
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- 6.
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True
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False
Correct Answer
A. True -
- 7.
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True
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False
Correct Answer
A. True -
- 8.
A heterogeneous equilibrium means that reactants and products are present in more than one state.
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True
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False
Correct Answer
A. TrueExplanation
A heterogeneous equilibrium refers to a chemical reaction where the reactants and products are present in different states. This means that they can exist in different phases, such as solid, liquid, or gas. In contrast, a homogeneous equilibrium occurs when all the reactants and products are in the same state. Therefore, the statement that a heterogeneous equilibrium means that reactants and products are present in more than one state is true.Rate this question:
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- 9.
If the equilibrium constant for a reaction at 300 K is 49.7, the concentration of the reactants will be greater than the concentration of the products.
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True
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False
Correct Answer
A. FalseExplanation
Based on the given information, the equilibrium constant for the reaction is 49.7. The equilibrium constant is defined as the ratio of the concentrations of products to the concentrations of reactants at equilibrium. Therefore, if the equilibrium constant is greater than 1, it indicates that the concentration of products is greater than the concentration of reactants at equilibrium. Since the given equilibrium constant is 49.7, it suggests that the concentration of products will be greater than the concentration of reactants at equilibrium. Therefore, the correct answer is False.Rate this question:
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- 10.
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0.16 mol/L
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0.0014 mol/L
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0.075 mol/L
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0.75 mol/L
Correct Answer
A. 0.075 mol/L -
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8.9 x 10-3 mol/L
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2.0 x 10-2 mol/L
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2.0 x 10-3 mol/L
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7.4 x 10-3 mol/L
Correct Answer
A. 2.0 x 10-2 mol/L -
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The solubility product expression describes the equilibrium between a sparingly soluble ionic compound
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The amount of substance added to solution.
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The number of moles in the reaction.
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Its ions in solution.
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The equilibrium constant.
Correct Answer
A. Its ions in solution.Explanation
The solubility product expression describes the equilibrium between a sparingly soluble ionic compound and its ions in solution. This expression is used to calculate the solubility of the compound and determine the concentration of its ions in the solution at equilibrium. It is based on the principle that the product of the ion concentrations raised to their respective stoichiometric coefficients is equal to a constant value at equilibrium. Therefore, the correct answer is "its ions in solution."Rate this question:
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- 13.
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The equilibrium shifts to the left.
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The equilibrium shifts to the right.
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The equilibrium does not change.
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The equilibrium constant changes.
Correct Answer
A. The equilibrium does not change. -
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Le Châtelier’s principle
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Common ion effect
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Solubility product constant
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Law of chemical equilibrium
Correct Answer
A. Le Châtelier’s principle -
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What is indicated by a large value for Keq?
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A solution is saturated.
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Products are favored in the reaction.
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Reactants are favored in the reaction.
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The reaction is endothermic.
Correct Answer
A. Products are favored in the reaction.Explanation
A large value for Keq indicates that the products are favored in the reaction. Keq, or the equilibrium constant, is a measure of the ratio of product concentrations to reactant concentrations at equilibrium. A large value of Keq means that the equilibrium position is shifted towards the products, indicating that the products are favored over the reactants in the reaction.Rate this question:
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- 16.
The value of any equilibrium constant is correct only at
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A specific volume.
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A specific pressure.
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A specific concentration.
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A specific temperature.
Correct Answer
A. A specific temperature.Explanation
The value of any equilibrium constant is correct only at a specific temperature because temperature affects the rate at which reactions occur and the balance between reactants and products. Changing the temperature alters the energy of the particles, which can either speed up or slow down the reaction. Therefore, the equilibrium constant, which represents the ratio of the concentrations of products and reactants at equilibrium, is only valid at a specific temperature.Rate this question:
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- 17.
Correct Answer
A. -
- 18.
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The temperature of the system increases.
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The temperature of the system decreases.
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More chlorine is produced.
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The temperature remains unaffected.
Correct Answer
A. The temperature of the system decreases. -
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According to Le Chatelier’s principle, when the volume is increased, the equilibrium shifts to the right. For which of the following reversible reactions is this true?
Correct Answer
A.Explanation
According to Le Chatelier's principle, when the volume is increased, the equilibrium shifts to the side with more moles of gas. This is because increasing the volume decreases the pressure, and the reaction will try to counteract this change by shifting in the direction that produces more moles of gas. Therefore, for a reversible reaction with more moles of gas on the right side, increasing the volume will shift the equilibrium to the right.Rate this question:
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- 20.
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Decrease in the volume of N2.
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Increase in the amount of catalyst.
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Decrease in pressure.
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Decrease in temperature.
Correct Answer
A. Increase in the amount of catalyst. -
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What might cause the solubility of a substance to decrease?
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A decrease in temperature
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A decrease in pressure
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The presence of a common ion
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All of the choices
Correct Answer
A. All of the choicesExplanation
All of the choices can cause the solubility of a substance to decrease. A decrease in temperature generally reduces the kinetic energy of the particles, making them less likely to overcome the attractive forces and dissolve. A decrease in pressure can also decrease solubility by reducing the number of gas molecules available to dissolve in a liquid. The presence of a common ion can cause a decrease in solubility through the common ion effect, where the presence of an ion already in solution reduces the solubility of a compound containing the same ion. Therefore, all of these factors can contribute to a decrease in solubility.Rate this question:
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- 22.
What can be determined if the ion product is compared to the solubility product constant?
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Equilibrium
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whether a substance will precipitate
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The law of mass action
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The volume of the solution
Correct Answer
A. whether a substance will precipitateExplanation
The solubility product constant is a value that represents the equilibrium between a solute and its ions in a saturated solution. It is determined by multiplying the concentrations of the ions raised to their respective stoichiometric coefficients. The ion product, on the other hand, is calculated by multiplying the concentrations of the ions in any given solution. By comparing the ion product to the solubility product constant, it can be determined whether a substance will precipitate. If the ion product is greater than the solubility product constant, the solution is supersaturated and precipitation will occur. If the ion product is less than the solubility product constant, the solution is unsaturated and no precipitation will occur.Rate this question:
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- 23.
When a reaction results in almost complete conversion of reactants to products, chemists say the reaction goes to ____________________.
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Completion
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Reversible reaction
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Chemical equilibrium
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Constant, equal
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. CompletionExplanation
When a reaction results in almost complete conversion of reactants to products, chemists say the reaction goes to completion. This means that there are minimal or no reactants left and the reaction has reached its maximum extent. In other words, all the reactants have been transformed into products, indicating that the reaction has proceeded to its fullest extent.Rate this question:
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- 24.
The solubility product of aluminum sulfate Al2(SO4)3 is given by the expression ____________________.
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Completion
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Reversible reaction
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Chemical equilibrium
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Constant, equal
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A.Explanation
The solubility product of aluminum sulfate Al2(SO4)3 is given by the expression "chemical equilibrium constant, equal". This means that the solubility product is equal to the product of the concentrations of the ions raised to their stoichiometric coefficients in the balanced chemical equation. This expression represents the state of equilibrium between the dissolved ions and the solid compound, indicating that the compound is in a saturated solution and no further dissolution or precipitation will occur.Rate this question:
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- 25.
At equilibrium, the concentrations of reactants and products are ____________________, but that does not mean that the amounts or concentrations are ____________________.
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Completion
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Reversible reaction
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Chemical equilibrium
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Constant, equal
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. Constant, equalExplanation
At equilibrium, the concentrations of reactants and products are constant, meaning they do not change over time. However, this does not imply that the amounts or concentrations of reactants and products are equal. The equilibrium constant, which is a ratio of the concentrations of products and reactants at equilibrium, determines the extent of the reaction and whether the reactants or products are present in higher concentrations. Therefore, the concentrations can be unequal at equilibrium depending on the specific reaction and its equilibrium constant.Rate this question:
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- 26.
____________________ is a state in which the forward and reverse reactions balance each other because they take place at equal rates.
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Completion
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Reversible reaction
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Chemical equilibrium
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Constant, equal
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. Chemical equilibriumExplanation
Chemical equilibrium is a state in which the forward and reverse reactions of a chemical reaction occur at equal rates, resulting in a balance between the reactants and products. This means that the concentration of the reactants and products remains constant over time. In other words, the reaction is in a state of dynamic balance, where the rate of the forward reaction is equal to the rate of the reverse reaction. This state is often represented by the double arrow symbol (⇌) in chemical equations.Rate this question:
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- 27.
A reaction that can occur in both the forward and the reverse directions is called a(n) ____________________.
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Completion
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Reversible reaction
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Chemical equilibrium
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Constant, equal
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. Reversible reactionExplanation
A reversible reaction is a reaction that can occur in both the forward and the reverse directions. In other words, the products of the reaction can react with each other to form the original reactants. This type of reaction reaches a state of chemical equilibrium, where the forward and reverse reactions are occurring at the same rate. The reaction can be reversed by changing the conditions, such as temperature or pressure. Therefore, "reversible reaction" is the correct answer for this question.Rate this question:
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- 28.
In a ____________________ reaction, two substances are in equilibrium if the concentration of each is doubled but the equilibrium constant remains unaffected
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Reversible
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Forward
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Chemical equilibrium
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Common ion
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. ReversibleExplanation
In a reversible reaction, two substances are in equilibrium if the concentration of each is doubled but the equilibrium constant remains unaffected. This means that increasing the concentration of the reactants or products does not change the position of the equilibrium. The reaction can proceed in both the forward and reverse directions, and doubling the concentrations of the substances does not shift the equilibrium towards either direction.Rate this question:
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- 29.
Equilibrium reaction in which the reactants and products are present in more than one physical state
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Heterogeneous equilibrium
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Chemical equilibrium
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Solubility product constant
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Common ion
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Le Châtelier’s principle
Correct Answer
A. Heterogeneous equilibriumExplanation
A heterogeneous equilibrium refers to an equilibrium reaction where the reactants and products are present in more than one physical state. This means that the substances involved in the reaction exist as a mixture of solids, liquids, and/or gases. In a heterogeneous equilibrium, the concentrations of the reactants and products may vary depending on the phase they are in. This is in contrast to a homogeneous equilibrium where all the reactants and products are in the same phase.Rate this question:
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- 30.
Barium sulfate is used when X rays are taken of the digestive system, based on the ____________________ effect.
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Reversible
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Forward
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Chemical equilibrium
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Common ion
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. Common ionExplanation
Barium sulfate is used when X rays are taken of the digestive system, based on the common ion effect. This effect occurs when the addition of a common ion, in this case, the sulfate ion, reduces the solubility of a slightly soluble compound, such as barium sulfate. By adding barium sulfate, which is not very soluble in water, to the digestive system, it helps to enhance the contrast in the X-ray images, allowing for better visualization of the digestive system.Rate this question:
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- 31.
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Reversible
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Forward
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Chemical equilibrium
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Common ion
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![Chemistry Ch18&19 Exam - Quiz]()
Correct Answer
A. Forward -
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If a stress is applied to a system at equilibrium, the system shifts in the direction that relieves the stress.
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Heterogeneous equilibrium
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Chemical equilibrium
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Solubility product constant
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Common ion
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Le Châtelier’s principle
Correct Answer
A. Le Châtelier’s principleExplanation
Le Châtelier's principle states that if a stress, such as a change in temperature, pressure, or concentration, is applied to a system at equilibrium, the system will shift in a way that counteracts the stress and restores equilibrium. In other words, if a stress is applied to a system, the system will adjust itself to relieve the stress and maintain equilibrium. This principle is widely used to predict and explain the behavior of chemical reactions and equilibria.Rate this question:
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- 33.
An ion that is part of two or more ionic compounds in solution
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Heterogeneous equilibrium
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Chemical equilibrium
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Solubility product constant
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Common ion
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Le Châtelier’s principle
Correct Answer
A. Common ionExplanation
A common ion refers to an ion that is present in multiple ionic compounds in solution. When a common ion is added to a solution, it can decrease the solubility of a compound by shifting the equilibrium towards the formation of a precipitate. This is due to Le Châtelier's principle, which states that a system will adjust to counteract any changes imposed upon it. The presence of a common ion reduces the concentration of one of the ions involved in the equilibrium, causing the equilibrium to shift in the opposite direction to restore the balance.Rate this question:
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- 34.
An equilibrium constant for the dissolving of a sparingly soluble ionic compound in water
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Heterogeneous equilibrium
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Chemical equilibrium
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Solubility product constant
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Common ion
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Le Châtelier’s principle
Correct Answer
A. Solubility product constantExplanation
The solubility product constant is the correct answer because it specifically refers to the equilibrium constant for the dissolving of a sparingly soluble ionic compound in water. This constant represents the equilibrium between the dissolved ions and the undissolved solid, and is used to calculate the solubility of the compound. The solubility product constant is a characteristic property of the compound and is independent of the amount of solid present.Rate this question:
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- 35.
A state in which the forward and reverse reactions balance each other because they take place at equal rates
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Heterogeneous equilibrium
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Chemical equilibrium
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Solubility product constant
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Common ion
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Le Châtelier’s principle
Correct Answer
A. Chemical equilibriumExplanation
Chemical equilibrium refers to a state in which the forward and reverse reactions of a chemical reaction occur at equal rates, resulting in a balance between the reactants and products. This state is achieved when the concentrations of reactants and products remain constant over time. At chemical equilibrium, the system is stable and there is no net change in the amounts of reactants and products. Therefore, the given answer, chemical equilibrium, accurately describes the state in which the forward and reverse reactions balance each other because they take place at equal rates.Rate this question:
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- 36.
The numerical value of the ratio of product concentrations to reactant concentrations, with the concentration of each reactant and product raised to the power corresponding to its coefficient in the balanced equation
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Equilibrium constant
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Reversible reaction
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Homogeneous equilibrium
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Law of chemical equilibrium
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Common ion effect
Correct Answer
A. Equilibrium constantExplanation
The equilibrium constant is a numerical value that represents the ratio of product concentrations to reactant concentrations, with each concentration raised to the power corresponding to its coefficient in the balanced equation. It is used to quantify the extent of a reversible reaction at equilibrium. The equilibrium constant is a fundamental concept in the law of chemical equilibrium, which describes the behavior of reactions in a homogeneous equilibrium. The common ion effect, on the other hand, refers to the suppression of ionization of a weak electrolyte in the presence of a strong electrolyte containing a common ion.Rate this question:
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- 37.
The solubility of a substance is lowered because of this.
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Equilibrium constant
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Reversible reaction
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Homogeneous equilibrium
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Law of chemical equilibrium
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Common ion effect
Correct Answer
A. Common ion effectExplanation
The common ion effect is the phenomenon where the solubility of a substance is decreased when a common ion is added to the solution. This occurs because the presence of the common ion reduces the concentration of the dissolved substance, shifting the equilibrium towards the solid form. As a result, the solubility of the substance is lowered.Rate this question:
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- 38.
At a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value.
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Equilibrium constant
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Reversible reaction
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Homogeneous equilibrium
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Law of chemical equilibrium
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Common ion effect
Correct Answer
A. Law of chemical equilibriumExplanation
The law of chemical equilibrium states that at a given temperature, a chemical system may reach a state in which a particular ratio of reactant and product concentrations has a constant value. This means that the forward and reverse reactions are occurring at equal rates, resulting in a dynamic equilibrium where the concentrations of reactants and products remain constant over time. The equilibrium constant is a numerical value that represents the ratio of product concentrations to reactant concentrations at equilibrium, and it is determined by the stoichiometry of the balanced equation for the reaction.Rate this question:
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- 39.
Equilibrium reaction in which all the reactants and products are in the same physical state
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Equilibrium constant
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Reversible reaction
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Homogeneous equilibrium
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Law of chemical equilibrium
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Common ion effect
Correct Answer
A. Homogeneous equilibriumExplanation
Homogeneous equilibrium refers to an equilibrium reaction in which all the reactants and products are in the same physical state. In other words, all the substances involved in the reaction are either in the gas phase, liquid phase, or solid phase. This type of equilibrium is characterized by a constant ratio of the concentrations of reactants and products, known as the equilibrium constant. It is governed by the law of chemical equilibrium, which states that at a given temperature, the ratio of the concentrations of reactants and products remains constant. The common ion effect, on the other hand, refers to the reduction in the solubility of a salt when a common ion is added to the solution.Rate this question:
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- 40.
A reaction that can occur in both the forward and the reverse directions
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Equilibrium constant
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Reversible reaction
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Homogeneous equilibrium
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Law of chemical equilibrium
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Common ion effect
Correct Answer
A. Reversible reactionExplanation
A reversible reaction is a reaction that can occur in both the forward and the reverse directions. This means that the reactants can form products, but the products can also react to form the original reactants. The equilibrium constant is a measure of the extent to which a reversible reaction proceeds in the forward or reverse direction. Therefore, the answer "reversible reaction" is the correct choice as it best describes a reaction that can occur in both directions.Rate this question:
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- 41.
Buffers resist change in pH.
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True
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False
Correct Answer
A. TrueExplanation
Buffers are solutions that are able to resist changes in pH when small amounts of acid or base are added to them. They contain a weak acid and its conjugate base, or a weak base and its conjugate acid. When an acid is added to a buffer solution, the weak base in the buffer reacts with the acid to form its conjugate acid, preventing a significant change in pH. Similarly, when a base is added, the weak acid in the buffer reacts with the base to form its conjugate base, again preventing a significant change in pH. Therefore, buffers do indeed resist changes in pH, making the statement true.Rate this question:
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- 42.
A neutral solution contains more hydroxide ions than hydrogen ions.
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True
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False
Correct Answer
A. FalseExplanation
A neutral solution contains an equal number of hydroxide ions and hydrogen ions, resulting in a balanced pH level of 7. Therefore, the statement that a neutral solution contains more hydroxide ions than hydrogen ions is false.Rate this question:
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- 43.
An aqueous solution of acids causes red litmus paper to turn blue.
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True
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False
Correct Answer
A. FalseExplanation
An aqueous solution of acids does not cause red litmus paper to turn blue. In fact, acids turn blue litmus paper red. Red litmus paper is used to test for the presence of bases, which will turn the paper blue. Therefore, the given statement is false.Rate this question:
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- 44.
A buffer system should contain considerably more acid than base.
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True
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False
Correct Answer
A. FalseExplanation
A buffer system should contain equal amounts of acid and base, or slightly more base than acid, in order to effectively resist changes in pH. Having considerably more acid than base would result in an unbalanced buffer system, making it less effective in maintaining a stable pH. Therefore, the given statement is false.Rate this question:
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- 45.
Specific buffer systems should be chosen based on the pH that must be maintained.
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True
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False
Correct Answer
A. TrueExplanation
The statement is true because different buffer systems are effective at different pH levels. Buffer systems are solutions that resist changes in pH when small amounts of acid or base are added. Each buffer system has a specific range of pH where it is most effective. Therefore, it is important to choose a buffer system that can maintain the desired pH level.Rate this question:
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- 46.
A buffer solution changes pH only a small amount even if large amounts of acid or base are added.
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True
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False
Correct Answer
A. FalseExplanation
A buffer solution is designed to resist changes in pH when small amounts of acid or base are added. However, if large amounts of acid or base are added to a buffer solution, it will not be able to effectively resist the change in pH and the pH of the solution will be significantly altered. Therefore, the statement that a buffer solution changes pH only a small amount even if large amounts of acid or base are added is incorrect.Rate this question:
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- 47.
An example of a buffer solution is a mixture of acetic acid and sodium acetate.
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True
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False
Correct Answer
A. TrueExplanation
A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added to it. It consists of a weak acid and its conjugate base, or a weak base and its conjugate acid. In the given example, acetic acid is a weak acid and sodium acetate is its conjugate base. When combined, they create a buffer solution that can maintain a relatively constant pH when small amounts of acid or base are added. Therefore, the statement is true.Rate this question:
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- 48.
A buffer can be a mixture of a weak acid and its conjugate base.
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True
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False
Correct Answer
A. TrueExplanation
A buffer is a solution that resists changes in pH when small amounts of acid or base are added to it. It consists of a weak acid and its conjugate base. The weak acid can donate hydrogen ions to neutralize any added base, while the conjugate base can accept hydrogen ions to neutralize any added acid. This allows the buffer to maintain a relatively constant pH. Therefore, the statement that a buffer can be a mixture of a weak acid and its conjugate base is true.Rate this question:
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- 49.
Acid A and acid B are of equal concentration and are tested with a conductivity apparatus. When the electrodes are placed in acid A, the bulb glows dimly. When they are placed in acid B, the bulb glows more brightly. Which of the following is true?
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Acid A is stronger than acid B.
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Acid B is stronger than acid A.
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Acid A and acid B are of equal strength.
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No comparison of strength can be made from the results.
Correct Answer
A. Acid B is stronger than acid A.Explanation
The conductivity of a solution is directly related to the concentration of ions present in the solution. In this case, when the electrodes are placed in acid A and the bulb glows dimly, it indicates that acid A has a lower concentration of ions and therefore lower conductivity. On the other hand, when the electrodes are placed in acid B and the bulb glows more brightly, it suggests that acid B has a higher concentration of ions and therefore higher conductivity. This implies that acid B is stronger than acid A in terms of ion concentration and conductivity.Rate this question:
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