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Questions and Answers
What does a large magnitude of Kc indicate about the concentrations of products and reactants?
What does a large magnitude of Kc indicate about the concentrations of products and reactants?
In the equilibrium constant expression for the reaction CaCO3(s) ⇌ CaO(s) + CO2(g), which species is included in the expression?
In the equilibrium constant expression for the reaction CaCO3(s) ⇌ CaO(s) + CO2(g), which species is included in the expression?
How is the equilibrium constant for an overall reaction derived from multiple equilibria?
How is the equilibrium constant for an overall reaction derived from multiple equilibria?
In a heterogeneous equilibrium, which of the following phases are involved?
In a heterogeneous equilibrium, which of the following phases are involved?
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What does the equilibrium constant Kp represent in relation to Kc?
What does the equilibrium constant Kp represent in relation to Kc?
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What characterizes a chemical equilibrium?
What characterizes a chemical equilibrium?
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What does the equilibrium constant (Keq) indicate when it is much greater than 1?
What does the equilibrium constant (Keq) indicate when it is much greater than 1?
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In the equilibrium constant expression $K_{eq} = \frac{[C]^c[D]^d}{[A]^a[B]^b}$, what do the symbols [A], [B], [C], and [D] represent?
In the equilibrium constant expression $K_{eq} = \frac{[C]^c[D]^d}{[A]^a[B]^b}$, what do the symbols [A], [B], [C], and [D] represent?
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What happens to the reaction quotient (Qc) if the concentrations of reactants are increased before equilibrium is reached?
What happens to the reaction quotient (Qc) if the concentrations of reactants are increased before equilibrium is reached?
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What does it mean if Keq is much smaller than 1?
What does it mean if Keq is much smaller than 1?
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Which of the following is true about the law of mass action?
Which of the following is true about the law of mass action?
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When does the reaction quotient (Qc) become equal to the equilibrium constant (Kc)?
When does the reaction quotient (Qc) become equal to the equilibrium constant (Kc)?
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What could cause a shift in the equilibrium position of a reaction?
What could cause a shift in the equilibrium position of a reaction?
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What must happen to the reactants if $Q_c < K_c$?
What must happen to the reactants if $Q_c < K_c$?
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Which statement is true if $K_c < 1$ for a reaction?
Which statement is true if $K_c < 1$ for a reaction?
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What do $K_c$ and $K_p$ measure?
What do $K_c$ and $K_p$ measure?
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In the equilibrium reaction $2NO(g) + O_2(g) ⇌ 2NO_2(g)$, which concentration contributes to the calculation of $K_c$?
In the equilibrium reaction $2NO(g) + O_2(g) ⇌ 2NO_2(g)$, which concentration contributes to the calculation of $K_c$?
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What is the role of $ riangle n$ in the relationship between $K_p$ and $K_c$?
What is the role of $ riangle n$ in the relationship between $K_p$ and $K_c$?
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For the reaction $HF(aq) + H_2O(l) ⇌ H_3O^+(aq) + F^-(aq)$, what can be concluded about $K_p$?
For the reaction $HF(aq) + H_2O(l) ⇌ H_3O^+(aq) + F^-(aq)$, what can be concluded about $K_p$?
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When does the reaction reach equilibrium in terms of $Q_c$ and $K_c$?
When does the reaction reach equilibrium in terms of $Q_c$ and $K_c$?
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What does a larger value of $K_c$ indicate about a reaction?
What does a larger value of $K_c$ indicate about a reaction?
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Study Notes
Chemical Equilibrium
- Chemical equilibrium occurs when the rates of forward and reverse reactions are equal, and the concentrations of reactants and products remain constant over time.
- Both forward and reverse reactions still occur at equilibrium, but there's no net change in concentration.
- Chemical equilibrium is dynamic.
Equilibrium Constant (Keq)
- The equilibrium constant (Keq) expression is based on the concentrations of products and reactants at equilibrium.
- Keq = [C]c[D]d / [A]a[B]b
- [A], [B], [C], and [D] are the molar concentrations of the chemical species.
- a, b, c, and d are the stoichiometric coefficients for the reacting species A, B, C, and D.
- The magnitude of Keq indicates whether the equilibrium favors products or reactants.
- If Keq >> 1, the equilibrium will favor products.
- If Keq << 1, the equilibrium will favor reactants.
Reaction Quotient (Qc)
- The reaction quotient (Qc) is used to determine the direction a reaction will proceed to reach equilibrium when the reaction is not at equilibrium.
- Qc = [products]coefficients / [reactants]coefficients
- Comparing Qc with Keq:
- If Qc < Keq, the reaction will proceed in the forward direction (reactants to products).
- If Qc = Keq, the reaction is at equilibrium.
- If Qc > Keq, the reaction will proceed in the reverse direction (products to reactants).
Types of Equilibrium
- Homogeneous Equilibria: All reactants and products are in the same phase (e.g., all gases).
- Heterogeneous Equilibria: Reactants and products are in different phases (e.g., solid, liquid, gas). Concentrations of solids and pure liquids are NOT included in the equilibrium expression.
Factors Affecting Equilibrium
- Concentration: Increasing the concentration of products shifts the equilibrium to the left, and decreasing the concentration of products shifts the equilibrium to the right.
- Volume and Pressure (for gases): Increasing pressure (decreasing volume) favors the side with fewer moles of gas. Decreasing pressure (increasing volume) favors the side with more moles of gas. Changes in pressure do not affect the concentrations of solids or liquids.
- Temperature: Increasing temperature favors endothermic reactions (absorbs heat). Decreasing temperature favors exothermic reactions (releases heat).
- Catalyst: A catalyst speeds up the rate of both the forward and reverse reactions, but it does not affect the position of equilibrium.
Acid-Base Equilibria
- Arrhenius Acid: Produces H+ ions in aqueous solutions.
- Arrhenius Base: Produces OH¯ ions in aqueous solutions.
- Bronsted-Lowry Acid: Proton (H+) donor.
- Bronsted-Lowry Base: Proton (H+) acceptor.
- Lewis Acid: Electron pair acceptor.
- Lewis Base: Electron pair donor.
- Strong Acids/Bases: Completely ionize in solution.
- Weak Acids/Bases: Partially ionize in solution.
Ionization of Water and pH
- Water undergoes self-ionization: H₂O + H₂O ↔ H₃O⁺ + OH⁻
- Ion product constant (Kw) = [H₃O⁺][OH⁻] = 1.0 × 10⁻¹⁴ at 25°C
- pH = -log[H₃O⁺] = -log[H⁺].
Solubility Equilibria
- Solubility: The amount of solute that dissolves in a given amount of solvent at a specific temperature to form a saturated solution.
- Molar Solubility: The number of moles of solute that dissolve in 1 liter of a saturated solution.
- Solubility Equilibrium: Exists in a saturated solution when the rate of dissolution equals the rate of precipitation.
- Solubility Product Constant (Ksp): The equilibrium constant for the dissolution of a sparingly soluble salt.
Metal-Complex Equilibria
- Complex Ion: An ion with a central metal cation bonded to one or more ligands (molecules or ions).
- Formation Constant (Kf): Equilibrium constant for the formation of a complex ion. Large Kf values indicate more stable complex ions.
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Description
Test your knowledge on chemical equilibrium concepts, including the dynamic nature of reactions, the equilibrium constant (Keq), and how concentrations of reactants and products relate at equilibrium. This quiz covers essential principles that govern equilibrium in chemical reactions.
