Pharmaceutical Analytical Chemistry I - Lecture 6
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Questions and Answers

What is the correct term for a reaction that involves an exchange of cations between two compounds in solution?

  • Metathesis reaction (correct)
  • Combination reaction
  • Decomposition reaction
  • Redox reaction

Which direction represents the formation in the equilibrium reaction A + B ↔ C + D?

  • Backward reaction
  • Complete reaction
  • Equilibrium reaction
  • Forward reaction (correct)

What occurs to the concentration of reactants as a reaction approaches equilibrium?

  • There is a constant increase
  • There is a constant decrease (correct)
  • It remains equal to products
  • It fluctuates unpredictably

At equilibrium, the rates of which of the following are equal?

<p>Forward and backward reactions (C)</p> Signup and view all the answers

Which statement about the amount of reactants and products at equilibrium is true?

<p>They remain constant but not necessarily equal (B)</p> Signup and view all the answers

What is defined as the change in concentration of a reactant or product per unit time?

<p>Reaction rate (B)</p> Signup and view all the answers

When a system at equilibrium is disturbed, what is expected to happen?

<p>The equilibrium will shift to restore balance (B)</p> Signup and view all the answers

What term describes a state where concentrations of reactants and products remain constant?

<p>Dynamic equilibrium (B)</p> Signup and view all the answers

What factor does NOT affect the rate of a chemical reaction?

<p>Presence of contaminants (D)</p> Signup and view all the answers

Which statement accurately describes the Law of Mass Action?

<p>The rate of a chemical reaction is directly proportional to the active masses of the reactants. (D)</p> Signup and view all the answers

If the molar concentrations of reactants A and B are both 2 M, what can be inferred about the reaction rate?

<p>The reaction rate will be different than when both concentrations are 1 M. (C)</p> Signup and view all the answers

What is the equilibrium constant represented in the equation?

<p>K represents the ratio of products' concentrations to reactants' concentrations at equilibrium. (A)</p> Signup and view all the answers

What happens to the reaction rate when the concentration of reactants increases?

<p>The reaction rate increases. (B)</p> Signup and view all the answers

Which of the following statements is true regarding covalently bonded molecules in reactions?

<p>They tend to have slower reaction rates compared to ionic reactions. (C)</p> Signup and view all the answers

Which term defines the rate of a reaction in which the concentration of reactants is at 1 M?

<p>Rate constant (B)</p> Signup and view all the answers

What is the likely outcome when physical nature of the medium of reaction changes?

<p>It may either increase or decrease the reaction rate. (A)</p> Signup and view all the answers

What is the relationship between the equilibrium constant Keq and the concentrations of reactants and products at equilibrium?

<p>Keq is calculated as the ratio of products to reactants concentrations. (A)</p> Signup and view all the answers

What happens to the equilibrium when the pressure is increased in a reaction where 4 moles of gas convert to 2 moles of gas?

<p>The equilibrium shifts toward the products. (C)</p> Signup and view all the answers

According to Le Chatelier’s principle, what is expected when the concentration of reactant A is increased?

<p>The equilibrium shifts to the right. (B)</p> Signup and view all the answers

If Keq is greater than 1, what can be inferred about the reaction?

<p>Products predominate at equilibrium. (A)</p> Signup and view all the answers

How does the addition of HCl affect the ionization of acetic acid?

<p>It decreases the ionization of acetic acid. (A)</p> Signup and view all the answers

Which statement about the effect of catalysts on Keq is true?

<p>Catalysts have no effect on the equilibrium constant Keq. (C)</p> Signup and view all the answers

What is the effect of adding AgNO3 to a saturated solution of AgCl?

<p>It decreases the solubility of AgCl. (A)</p> Signup and view all the answers

How does Le Chatelier's Principle describe the response of a system at equilibrium when a stress is applied?

<p>The system shifts in a direction to decrease stress. (A)</p> Signup and view all the answers

In an exothermic reaction, what happens when energy is added?

<p>The equilibrium shifts to the left. (B)</p> Signup and view all the answers

Which of the following scenarios would not result in a shift of equilibrium?

<p>Increasing the pressure in a reaction with equal moles of gas on both sides. (C)</p> Signup and view all the answers

What effect does the common ion effect have on weak acids or bases?

<p>It suppresses their ionization. (C)</p> Signup and view all the answers

Which factor does not influence the equilibrium position of a reaction?

<p>Presence of catalysts. (C)</p> Signup and view all the answers

If the concentration of a product is increased, what is the expected effect on the equilibrium position?

<p>The equilibrium shifts to the left. (D)</p> Signup and view all the answers

For a reaction involving gases, how does an increase in pressure affect the equilibrium position?

<p>It favors the side with fewer moles of gas. (A)</p> Signup and view all the answers

Which reaction demonstrates no change in total moles of gas during pressure alteration?

<p>H2 + I2 ⇌ 2 HI (A)</p> Signup and view all the answers

What is true about the equilibrium constant's dependence on temperature?

<p>Keq can vary with temperature and pressure. (D)</p> Signup and view all the answers

Flashcards

Metathesis reaction

A chemical reaction where two compounds in solution exchange cations with their respective anions. Also known as a double replacement reaction.

Chemical Equilibrium

A state where the rates of the forward and backward reactions are equal, and the concentrations of reactants and products remain constant.

Forward reaction

The conversion of reactants to products.

Backward reaction

The conversion of products back to reactants.

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Dynamic equilibrium

Equilibrium where reactions are still occurring in both directions, but the net change in concentration is zero.

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Reaction rate

The change in concentration of a reactant or product per unit of time.

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Equilibrium concentrations

The relative concentration of reactants and products at equilibrium.

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Equilibrium Amounts

Amounts of reactants and products remain constant at equilibrium but are not necessarily equal.

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Reaction Rate

The speed at which a chemical reaction occurs.

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Factors Affecting Reaction Rate

Variables that influence how quickly a chemical reaction proceeds.

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Active Mass

Molar concentration (moles per liter) of a substance in a reaction.

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Law of Mass Action

The rate of a chemical reaction is proportional to the product of the active masses of the reactants, each raised to a power equal to its stoichiometric coefficient.

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Rate Constant (k)

A proportionality constant in the rate law, representing the speed of a reaction.

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Equilibrium Constant (Keq)

A value that describes the ratio of product to reactant concentrations at equilibrium.

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Stoichiometric Coefficient

The number of moles of each substance in a balanced chemical equation.

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Collision Theory

Reactions occur when reactants collide with sufficient energy and proper orientation.

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Equilibrium Constant (Keq)

A constant value that describes the ratio of product concentrations to reactant concentrations at equilibrium.

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Keq > 1

Indicates that the forward reaction is more favorable and more product is present at equilibrium.

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Keq < 1

Indicates that the reverse reaction is more favorable and more reactant is present at equilibrium.

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Le Chatelier's Principle

If a stress (like temperature or concentration change) is applied to a system in equilibrium, the system will shift to relieve the stress.

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Exothermic reaction

A reaction that releases heat.

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Endothermic reaction

A reaction that absorbs heat.

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Pressure effect on equilibrium

Pressure affects equilibrium only if gases are involved.

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Catalyst effect on Keq

A catalyst affects the rates of both forward and reverse reactions equally and has no effect on the equilibrium constant (Keq).

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Le Chatelier's Principle

If a change is applied to a system in equilibrium, the system will shift in a direction that reduces the effect of that change.

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Pressure Increase & Equilibrium

Increased pressure favors the reaction producing fewer gas moles. Reduces the pressure.

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Concentration Shift

Increasing reactant concentration shifts equilibrium to product side; vice-versa, reducing concentration shifts equilibrium to reactant side.

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Common Ion Effect

Adding an ion already present decreases the solubility/ionization of a weak electrolyte.

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Equilibrium and no change in moles

No change occurs if increasing pressure does not change the number of moles of gas involved in a reaction.

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Solubility Suppression

Adding a common ion reduces the solubility of a solid substance in a solution.

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Equilibrium and Acetic Acid/HCl

Adding HCl to acetic acid solution shifts equilibrium to reduced ionization of the acid and reduce the strength of acetic acid.

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AgCl Solubility in AgNO3

AgCl's solubility decreases in a solution containing AgNO3(Ag+ is a common ion).

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Study Notes

Introduction to General Inorganic Chemistry

  • Pharmaceutical Analytical Chemistry I (PC 111), Level I, Pharm D Clinical
  • Lecture 6
  • Presented by Dr. Galal Magdy, PhD

Metathesis Reactions

  • Metathesis (double replacement) reactions involve two compounds in solution, exchanging cations with anions
  • Example: AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)

Chemical Equilibrium

  • A chemical reaction has a forward and a backward reaction
  • Products of a reaction interact to form reactants
  • This occurs simultaneously in both directions
  • Reaction rates change as the reaction progresses
  • Equilibrium occurs when forward reaction rate equals reverse reaction rate
  • At equilibrium, concentrations of reactants and products remain constant

Dynamic Equilibrium

  • A state of equilibrium where the forward and backward reaction rates are equal, yet there is continuous exchange of products and reactants
  • Concentrations of reactants and products are constant

Reaction Rate

  • Reaction rate = change in reactant/product concentration per unit time
  • Some reactions are fast, others are slow
  • Generally, ion-based reactions are rapid
  • Covalent reactions are often slower
  • Examples:
    • Rapid: Ag⁺(aq) + Cl⁻(aq) → AgCl(s)
    • Slow: Iron to iron oxide (rust)

Factors Affecting Reaction Rate

  • Nature of reactants
  • Reactant concentration
  • Pressure (gaseous systems)
  • Temperature
  • Catalysts
  • Physical nature of reaction medium

Effect of Concentration on Reaction Rate

  • Collisions between ions or molecules lead to product formation
  • Increasing the number of reactant moles increases collision chances, thus increasing reaction rate
  • The law describing concentration's effect on reaction rate is the Law of Mass Action (Law of Chemical Equilibrium)
  • Reaction rate is directly proportional to the active masses (molar concentrations) of reacting substances

Rate Constant

  • The rate constant (k) is the proportionality constant relating the rate of a reaction to the concentrations of reactants
  • If reactant concentrations are 1 M, the rate equals the rate constant
  • Rate = k[A]m[B]n

Equilibrium Constant (Keq)

  • The equilibrium constant (Keq) is the ratio of the rate constant for the forward reaction (k₁) to the rate constant for the reverse reaction (k₂) at equilibrium
  • The ratio is equal to the molar concentration of products raised to their respective stoichiometric coefficients divided by a similar term for reactants Keq = ([C]c[D]d)/([A]a[B]b)

Factors Affecting Keq

  • Keq is not affected by catalysts, concentration changes, or equilibrium position changes
  • Keq is affected only by temperature and pressure and depends on reactant nature

Le Chatelier's Principle

  • When a stress is applied to a system in equilibrium, the equilibrium shifts in a direction that neutralizes the stress
  • Factors affecting the reaction equilibrium: temperature, pressure, and concentration

Temperature

  • Exothermic reaction: Adding energy shifts equilibrium to the left
  • Endothermic reaction: Adding energy shifts equilibrium to the right

Pressure

  • Pressure affects equilibrium only if one or more reactants or products are gases
  • Increasing pressure shifts equilibrium towards the side with fewer moles of gas

Concentration

  • Increasing reactant concentration shifts equilibrium to the right
  • Increasing product concentration shifts equilibrium to the left

Common Ion Effect

  • Adding a strong electrolyte with a common ion to a solution of a weak electrolyte decreases the concentration of the common ion
  • It suppresses the ionization of weak acids or bases

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Lecture 6 - General Inorganic Chemistry PDF

Description

This quiz covers key concepts from Lecture 6 of Pharmaceutical Analytical Chemistry I. It focuses on metathesis reactions, chemical equilibrium, and dynamic equilibrium, providing examples and explanations to enhance your understanding. Test your knowledge on these fundamental topics essential for a Clinical Pharm D program.

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