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Questions and Answers
What is the pH calculation for salts of weak acid and strong base, for example CH3COONa?
What is the pH calculation for salts of weak acid and strong base, for example CH3COONa?
Which type of buffer solution is designed to resist changes in pH when small amounts of acid or alkali are added?
Which type of buffer solution is designed to resist changes in pH when small amounts of acid or alkali are added?
In which category does a salt with solubility greater than 0.1M fall?
In which category does a salt with solubility greater than 0.1M fall?
What is the pH calculation for salts of strong acid and weak base, such as NH4Cl?
What is the pH calculation for salts of strong acid and weak base, such as NH4Cl?
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What does a deviation in pH from the normal range in body fluids indicate?
What does a deviation in pH from the normal range in body fluids indicate?
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What ions are produced when NaCl is dissolved in an aqueous solution?
What ions are produced when NaCl is dissolved in an aqueous solution?
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Which of the following is an example of a weak electrolyte?
Which of the following is an example of a weak electrolyte?
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According to the Arrhenius theory, what do acids produce when dissolved in water?
According to the Arrhenius theory, what do acids produce when dissolved in water?
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In the Brönsted-Lowry theory, what role does a base play?
In the Brönsted-Lowry theory, what role does a base play?
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Which of the following compounds is classified as a strong electrolyte?
Which of the following compounds is classified as a strong electrolyte?
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What is the product of the ionization of sodium hydroxide (NaOH) in water?
What is the product of the ionization of sodium hydroxide (NaOH) in water?
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What characterizes a strong electrolyte?
What characterizes a strong electrolyte?
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In the context of Lewis theory, which statement is true about acids?
In the context of Lewis theory, which statement is true about acids?
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How does a positive $ΔH$ affect the equilibrium constant of an endothermic reaction as temperature changes?
How does a positive $ΔH$ affect the equilibrium constant of an endothermic reaction as temperature changes?
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What is the primary effect of changing pressure on a gaseous reaction when the number of moles of products differs?
What is the primary effect of changing pressure on a gaseous reaction when the number of moles of products differs?
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When the volume of a system decreases, how does the equilibrium shift?
When the volume of a system decreases, how does the equilibrium shift?
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What role does a catalyst play in a chemical reaction?
What role does a catalyst play in a chemical reaction?
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What occurs when an inert gas is added to a system at constant volume?
What occurs when an inert gas is added to a system at constant volume?
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Which of the following statements relates to ionic equilibrium in solution?
Which of the following statements relates to ionic equilibrium in solution?
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According to Le-Chatlier’s principle, which factors can affect the equilibrium in a reaction?
According to Le-Chatlier’s principle, which factors can affect the equilibrium in a reaction?
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In the reaction $Fe^{3+} (aq) + SCN^{-} (aq) \rightleftharpoons [Fe(SCN)]^{2+} (aq)$, what happens when the concentration of $SCN^{-}$ increases?
In the reaction $Fe^{3+} (aq) + SCN^{-} (aq) \rightleftharpoons [Fe(SCN)]^{2+} (aq)$, what happens when the concentration of $SCN^{-}$ increases?
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What does the term $K_a$ represent in acid-base chemistry?
What does the term $K_a$ represent in acid-base chemistry?
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How is the equilibrium concentration of the acid $HX$ expressed when ionization occurs?
How is the equilibrium concentration of the acid $HX$ expressed when ionization occurs?
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What is the correct expression for the base ionization constant $K_b$?
What is the correct expression for the base ionization constant $K_b$?
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Which equation represents the ionization of the weak base $MOH$?
Which equation represents the ionization of the weak base $MOH$?
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What relationship does $pK_a$ have with the acid dissociation constant $K_a$?
What relationship does $pK_a$ have with the acid dissociation constant $K_a$?
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How do salts behave in water during hydrolysis?
How do salts behave in water during hydrolysis?
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If $C$ is the initial concentration of a weak acid, what represents the concentration of the dissociated ion at equilibrium?
If $C$ is the initial concentration of a weak acid, what represents the concentration of the dissociated ion at equilibrium?
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Which statement is true about the equilibrium constant for weak acids and bases?
Which statement is true about the equilibrium constant for weak acids and bases?
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What does the equilibrium constant indicate about a reaction?
What does the equilibrium constant indicate about a reaction?
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What happens to the value of the equilibrium constant when the reaction is reversed?
What happens to the value of the equilibrium constant when the reaction is reversed?
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How is the equilibrium constant affected when the equation is multiplied by 2?
How is the equilibrium constant affected when the equation is multiplied by 2?
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If the equilibrium constant is greater than 1000, which of the following can be concluded?
If the equilibrium constant is greater than 1000, which of the following can be concluded?
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What does a reaction quotient Q indicate when Q is less than K?
What does a reaction quotient Q indicate when Q is less than K?
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In a scenario where you know the initial concentrations but the equilibrium concentrations are unknown, what is the first step you must take?
In a scenario where you know the initial concentrations but the equilibrium concentrations are unknown, what is the first step you must take?
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Which of the following statements about catalysts in a reaction is correct?
Which of the following statements about catalysts in a reaction is correct?
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What is the purpose of calculating the reaction quotient Q?
What is the purpose of calculating the reaction quotient Q?
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What type of equilibrium is present when reactants and products have more than one phase?
What type of equilibrium is present when reactants and products have more than one phase?
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According to Le Chatelier's principle, what happens when the concentration of a reactant is increased?
According to Le Chatelier's principle, what happens when the concentration of a reactant is increased?
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What is the general effect of temperature increase on an exothermic reaction's equilibrium constant?
What is the general effect of temperature increase on an exothermic reaction's equilibrium constant?
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What type of equilibrium exists between water vapor and liquid water?
What type of equilibrium exists between water vapor and liquid water?
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What consequence does a change in pressure have on equilibrium involving gases?
What consequence does a change in pressure have on equilibrium involving gases?
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When a solid is in equilibrium with its saturated solution, what type of equilibrium is this considered?
When a solid is in equilibrium with its saturated solution, what type of equilibrium is this considered?
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Which factor does NOT affect the equilibrium position of a reaction?
Which factor does NOT affect the equilibrium position of a reaction?
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What happens to the equilibrium composition when a product is removed from a system at equilibrium?
What happens to the equilibrium composition when a product is removed from a system at equilibrium?
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Study Notes
Equilibrium in Chemistry
- Equilibrium is a dynamic process where the rates of forward and backward reactions are equal, resulting in no net change in the concentrations of reactants and products.
- At equilibrium, the rate of evaporation equals the rate of condensation.
- Equilibrium mixture is a mixture of reactants and products in their equilibrium state.
Equilibrium in Physical Processes
- Equilibrium in physical processes, such as phase transformations (solid-liquid, liquid-gas, solid-gas), can be better understood by observing characteristics at equilibrium.
- Examples include solid-liquid equilibrium (ice and water at a specific temperature and pressure), and liquid-vapour equilibrium (liquid and its vapor).
- Solid-liquid equilibrium: At a given temperature and pressure, both processes occur simultaneously and at the same rate. (Ice melting and water freezing.)
- Liquid-vapour: The rate of evaporation and condensation are equal, maintaining a constant vapor pressure.
- Important factors affecting phase transformations may include temperature and pressure.
Equilibrium in Chemical Processes
- Chemical equilibrium describes reversible reactions where the forward and reverse reaction rates are equal at a specific temperature.
- Reversible reactions show a decrease in reactants and an increase in products over time.
- Irreversible reactions proceed in one direction only until the reactants are consumed.
- Equilibrium is a dynamic state where the forward and reverse reactions occur at the same rate, so the concentrations of reactants and products remain constant.
- A state of equilibrium is characterized by a minimum Gibbs free energy.
Equilibrium Constant
- At a given temperature, a constant ratio exists between products and reactants at equilibrium.
- Equilibrium constant (K) depends only on temperature, not initial concentrations. Larger K values favor products more than reactants.
- For a reversible reaction
aA + bB ⇌ cC + dD, the equilibrium constant is expressed as:K = [C]^c[D]^d / [A]^a[B]^b.
Calculating Equilibrium Concentrations
- In problems where initial concentrations are known but equilibrium concentrations are not, a three-step process is used include:
- Writing a balanced equation
- Setting up a table listing initial concentrations, changes, and equilibrium concentrations.
- Substituting equilibrium concentrations into the equilibrium constant expression.
Predicting the Direction of Reaction
- The reaction quotient (Q) allows predicting if the reaction will shift toward products or reactants.
- If
Q < K: The ratio of products to reactants is less than that at equilibrium, so the reaction will shift forward (toward products). - If
Q > K: The ratio of products to reactants is greater than that at equilibrium, so the reaction will shift backward (toward reactants). - If
Q = K: The ratio of products to reactants is equal to that at equilibrium, and the reaction is at equilibrium.
Effect of Changing Conditions on Equilibrium
- Le Chatelier's principle describes how changes in conditions (concentration, temperature, pressure, catalyst) affect equilibrium—systems respond to counteract the change.
- Concentration changes cause a shift to the side that consumes the added substance, or produces substance that's removed.
- Temperature changes favor the exothermic process to counteract temperature changes, either increasing or decreasing temperature depending on the sign of enthalpy changes.
- Pressure changes shift the equilibrium toward the side with fewer gas molecules to counteract the pressure change.
Homogeneous and Heterogeneous Equilibria
- Homogeneous equilibrium involves all reactants and products in the same phase.
- Heterogeneous equilibrium involves reactants and products in different phases.
Ionic Equilibria
- Ionic equilibria involve the ionization of electrolytes (strong or weak) in solution, and these processes reach equilibrium.
- Strong electrolytes completely dissociate, while weak electrolytes partially dissociate.
Hydrolysis of Salts
- Salt hydrolysis occurs when the ions from a salt react with water to produce an acidic or basic solution.
- Strength of electrolyte is relevant in these reactions.
Buffer Solutions
- Solutions that resist changes in pH upon addition of small amounts of acid or base.
- Mixtures of a weak acid or base and its conjugate base or acid create buffer solutions. Buffers maintain constant pH.
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Description
This quiz explores the concept of equilibrium in both chemical reactions and physical processes. It covers dynamic equilibrium, phase transformations, and examples such as solid-liquid and liquid-vapor equilibria. Test your understanding of how these equilibria operate and their implications in various scenarios.
