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79 Cards in this Set
- Front
- Back
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The double arrow in an equation indicates what? |
That a reaction can occur in both the forward and reverse directions and can reach chemical equilibrium. |
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What does K represent? |
The equilibrium constant. |
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The value of K is a measure of what? |
Of how far a reaction proceeds. |
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What does a large K value mean? What does a small K value mean? |
The reaction lies far to the right at equilibrium with a high concentration of products and a low concentration of reactants. The reaction lies far to the left at equilibrium with a high concentration of reactants and a low concentration of products. |
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Any system at equilibrium responds to changes in ways that do what? |
In ways that maintain equilibrium. |
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In order to maintain equilibrium, hemoglobin binds oxygen when the surrounding oxygen concentration is _______ but it releases oxygen when the surrounding oxygen concentration is ______. |
In order to maintain equilibrium, hemoglobin binds oxygen when the surrounding oxygen concentration is high but it releases oxygen when the surrounding oxygen concentration is low. |
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___________ _______________ for a chemical reaction is the condition in which the rate of the forward reaction equals the rate of the reverse reaction. |
Dynamic equilibrium for a chemical reaction is the condition in which the rate of the forward reaction equals the rate of the reverse reaction. |
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T/F Reaction rates generally increase with increasing concentration of the reactants and decrease with decreasing concentration of the reactants. T/F Not all chemical reactions are even theoretically reversible. |
True False. Nearly all chemical reactions are at least theoretically reversible. In many cases the reversibility is so small that it can be ignored. |
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_____________ _____________ is dynamic because the forward and reverse reactions are still occurring, they are just occurring at the same rate. Even though concentrations of reactants and products no longer change at _____________, the concentrations of reactants and products are not equal to one another at _____________. |
Dynamic equilibrium is dynamic because the forward and reverse reactions are still occurring, they are just occurring at the same rate. Even though concentrations of reactants and products no longer change at equilibrium, the concentrations of reactants and products are not equal to one another at equilibrium. |
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Dynamic Equilibrium: Rate of forward reaction = ______________________. Concentrations of reactants and products no longer change. |
Dynamic Equilibrium: Rate of forward reaction = rate of reverse reaction. Concentrations of reactants and products no longer change. |
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We can quantify the relative concentrations of reactants and products at equilibrium with a quantity called... |
... the equilibrium constant (K). |
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T/F We define the equilibrium constant (K) for the reaction as the ratio - at equilibrium - of the concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coefficients. |
True |
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How do we distinguish between the equilibrium constant and the Kelvin unit of temperature? |
Kelvin: K (capital k) Equilibrium Constant: K (italicized k) |
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The relationship between the balanced chemical equation and the expression of the equilibrium constant is known as what? |
The law of mass action. |
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If this is the balanced chemical equation, how do you set up the equilibrium constant (K) equation? |
This is the Law of Mass Action. |
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The equilibrium constant says nothing about how _____ a reaction reaches equilibrium, only how _____ the reaction has proceeded once equilibrium is reached. |
The equilibrium constant says nothing about how fast a reaction reaches equilibrium, only how far the reaction has proceeded once equilibrium is reached. |
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K << 1 |
Reverse reaction is favored and the forward reaction does not proceed very far. |
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K ≈ 1 |
Neither direction is favored and the forward reaction proceeds about halfway. |
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K >> 1 |
Forward reaction is favored and the forward reaction proceeds essentially to completion. |
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T/F There are three modifications we can do on the equilibrium constant. |
True |
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If we reverse an equation, what do we do to the equilibrium constant? |
We invert it. |
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If we multiply the coefficients in an equation by a factor, what do we do to the equilibrium constant? |
We raise the equilibrium constant to the same factor. |
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If we add two or more individual chemical equations to obtain an overall equation, What do we do to the equilibrium constants? |
We multiple the corresponding equilibrium constants by each other to obtain the overall equilibrium constant. |
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When we multiply the coefficients in the equation by a factor, we raise the equilibrium constant to the same factor. If that factor is a fractional quantity, what do we do? |
We raise K to the same fractional quantity. |
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For gaseous reactions, the partial pressure of a particular gas is proportional to its ________________. We can also express the equilibrium constant in terms of the ___________ ____________ of the reactants and products. |
For gaseous reactions, the partial pressure of a particular gas is proportional to its concentration. We can also express the equilibrium constant in terms of the partial pressures of the reactants and products. |
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The equilibrium constant with respect to concentration in molarity. |
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The equilibrium constant with respect to the partial pressures in atmospheres. |
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T/F The expression for Kp takes the form of the expression for Kc, except that we use the partial pressure of each gas in place of its concentration. |
True |
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The partial pressure of gas A in units of atmosphere. |
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Because the partial pressure of a gas in atmosphere is not the same as its concentration in molarity, the value of Kp for a reaction is not necessarily equal to the value of Kc. However, we can derive a relationship between the two constants, as long as what? |
As long as the gases are behaving ideally. |
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What is this? |
Partial Pressure-Concentration Equilibrium Constant Relationship |
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In the equation of the partial pressure-concentration equilibrium constant, the quantity DELTA n represents what? |
The difference between the number of moles of gaseous products and gaseous reactants. |
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What does this mean? |
Kp is equal to Kc. |
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T/F When expressing the value of the equilibrium constant, we always include the units. |
False. When expressing the value of the equilibrium constant, we do not include the units. |
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Write an expression for the equilibrium constant (Kc) for this chemical equation... |
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T/F The concentrations within Kc should always be written in moles per liter (M), while Kc is unitless. |
True |
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Pure ________ are not included in the equilibrium expression. Similarly, pure ________ are also excluded from the equilibrium expression. |
Pure solids are not included in the equilibrium expression. Similarly, pure liquids are also excluded from the equilibrium expression. |
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T/F Equilibrium constants depend on temperature, even though temperature has not formal part in the calculation. |
True |
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What does ICE stand for? |
I = Initial C = Change E = Equilibrium |
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What if a reaction mixture not at equilibrium contains both reactants and products? Can we predict the direction of change for such a mixture? |
Yes. To gauge the progress of a reaction relative to equilibrium, we use a quantity called the reaction quotient. |
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T/F The definition of the reaction quotient takes the same form as the definition of the equilibrium constant, except that the reaction need not be at equilibrium. |
True |
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Reaction Quotient of the Concentrations |
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Reaction Quotient of the Partial Pressures |
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The reaction quotient is useful because the value of ____ relative to ____ is a measure of the progress of the reaction toward equilibrium. At equilibrium, the reaction quotient is equal to the equilibrium constant. |
The reaction quotient is useful because the value of Q relative to K is a measure of the progress of the reaction toward equilibrium. At equilibrium, the reaction quotient is equal to the equilibrium constant. |
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Reaction goes to the right (toward the products). |
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Reaction goes to the left (toward the reactants). |
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Reaction is at equilibrium. |
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T/F At a given temperature, K only has one value, while Q has many different values. |
True |
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What does this mean? |
The mixture contains only reactants. The reaction quotient is zero. |
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What does this mean? |
The mixture contains only products. The reaction quotient is infinity. |
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What does this mean? |
The mixture contains both reactants and products. The reaction quotient is one. |
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What is this? |
The quadratic formula |
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What is the quadratic formula? |
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When using the "x is small approximation," the ratio of x to the number it is subtracted from should be less than what value? |
0.05 or 5% |
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How is Le Châtelier pronounced? |
Le-sha-te-lyay |
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What is the name of this principle? When a chemical system at equilibrium is disturbed, the system shifts in a direction that minimizes the disturbance. |
Le Châtelier's principle |
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What happens when a chemical system already at equilibrium is disturbed? Le Châtelier's principle states that... |
... the chemical system responds to minimize the disturbance. |
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What is the reaction quotient (Qc) defined as? |
The ratio of the concentrations of the products raised to their stoichiometric coefficients divided by the concentrations of the reactants raised to their stoichiometric coefficients. |
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Lowering the concentration of a reactant (which makes Q > K) causes the system to shift in the direction of the ____________ to minimize the disturbance. Lowering the concentration of a product (which makes Q < K) causes the system to shift in the direction of the ____________. |
Lowering the concentration of a reactant (which makes Q > K) causes the system to shift in the direction of the reactants to minimize the disturbance. Lowering the concentration of a product (which makes Q < K) causes the system to shift in the direction of the products. |
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What is this? |
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A change in volume, like a change in concentration, generally changes the value of what? |
Q |
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We can express the concentration of any substance as the number of moles of the substance divided by the volume. What is the formula for this? |
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According to Le Châtelier's principle, what happens to gas particles when there is an increase of pressure? According to Le Châtelier's principle, what happens to gas particles when there is a decrease of pressure? |
Gas particles tend to decrease in number if possible. Gas particles tend to increase in number if possible. |
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Increasing the concentration of one or more of the reactants (which makes Q
Increasing the concentration of one or more of the products (which makes Q>K) causes the reaction to...
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... shift to the right (in the direction of the products).
... shift to the left (in the direction of the reactants). |
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Decreasing the concentration of one or more of the reactants (which makes Q>K) causes the reaction to...
Decreasing the concentration of one or more of the products (which makes Q |
... shift to the left (in the direction of the reactants).
... shift to the right (in the direction of the products).
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Consider a reaction mixture at equilibrium. What happens if we keep the ___________ the same but increase the ___________ by adding an inert gas to the mixture? Although the overall ___________ of the mixture increases, the ___________ of the reaction mixture does not change and so Q does not change. Consequently, there is no effect, and the reaction does not shift in either direction. Similarly, if a reaction has equal ___________ of gas particles on both sides of the reaction, the effects of a ___________ change on Q cancel each other out and there is no effect on the reaction. |
Consider a reaction mixture at equilibrium. What happens if we keep the volume the same but increase the pressure by adding an inert gas to the mixture? Although the overall pressure of the mixture increases, the volume of the reaction mixture does not change and so Q does not change. Consequently, there is no effect, and the reaction does not shift in either direction. Similarly, if a reaction has equal moles of gas particles on both sides of the reaction, the effects of a volume change on Q cancel each other out and there is no effect on the reaction. |
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Decreasing the volume causes the reaction to shift in the direction that has... Increasing the volume causes the reaction to shift in the direction that has... T/F Adding an inert gas to the mixture at a fixed volume has no effect on the equilibrium. When a reaction has an equal number of moles of gas on both sides of the chemical equation, a change in volume produces... |
... the fewer moles of gas particles. ... the greater number of moles of gas particles. True ... no effect on the equilibrium. |
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When a system at equilibrium is disturbed by a change in concentration or a change in volume, the equilibrium shifts to counter the change, but the equilibrium constant... In other words, changes in volume or concentration generally change Q, not K, and the system responds by shifting so that Q becomes equal to K. However, a change in temperature changes what? |
... does not change. The actual value of the equilibrium constant. |
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T/F If we decrease the temperature of a reaction mixture at equilibrium, the reaction shifts in the direction that tends to decrease the temperature and vice versa. |
False. If we increase the temperature of a reaction mixture at equilibrium, the reaction shifts in the direction that tends to decrease the temperature and vice versa. |
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What kind of reaction is this? |
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What kind of reaction is this? |
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T/F We can think of heat as a reactant in an exothermic reaction. T/F We can think of heat as a product in an endothermic reaction. |
False. We can think of heat as a product in an exothermic reaction. False. We can think of heat as a reactant in an endothermic reaction. |
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At constant pressure, raising the temperature of an exothermic reaction - think of this as adding heat - is similar to adding more product, causing the reaction to... T/F Changing the temperature does change the value of the equilibrium constant. |
... shift left. True. |
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At constant pressure, raising the temperature of an endothermic reaction is similar to adding more reactant, causing the reaction to... Adding heat favors the _______________ direction. Removing heat favors the _______________ direction. |
... shift right. Adding heat favors the endothermic direction. Removing heat favors the exothermic direction. |
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In an exothermic chemical reaction, what is heat? In an endothermic chemical reaction, what is heat? |
A product. A reactant. |
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Increasing the temperature causes an exothermic reaction to shift _____ (_____________________); the value of the equilibrium constant ___________. Decreasing the temperature causes an exothermic reaction to shift _______ (____________________); the value of the equilibrium constant ___________. |
Increasing the temperature causes an exothermic reaction to shift left (in the direction of the reactants); the value of the equilibrium constant decreases. Decreasing the temperature causes an exothermic reaction to shift right (in the direction of the products); the value of the equilibrium constant increases. |
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Increasing the temperature causes an endothermic reaction to shift _____ (_____________________); the equilibrium constant ___________. Decreasing the temperature causes an endothermic reaction to shift _______ (____________________); the equilibrium constant ___________. |
Increasing the temperature causes an endothermic reaction to shift right (in the direction of the products); the equilibrium constant increases. Decreasing the temperature causes an endothermic reaction to shift left (in the direction of the reactants); the equilibrium constant decreases. |
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Equivalent to adding a reactant, causing the reaction to shift to the right. Equivalent to removing a reactant, causing the reaction to shift to the left. |
