We have provided 60 MCQs on Redox Titrations, Unit-4, 1st semester, Pharmaceutical Analysis, B. Pharma.
We have covered following topics.
- (a) Concepts of oxidation and reduction.
- (b) Types of redox titrations (Principles and applications) Cerimetry, Iodimetry, Iodometry, Bromatometry, Dichrometry, Titration with potassium iodate
Table of Contents
MCQ on Redox Titration
Define oxidation and reduction in the context of redox reactions.
- A) Oxidation is the gain of electrons; reduction is the loss of electrons.
- B) Oxidation is the loss of electrons; reduction is the gain of electrons.
- C) Oxidation is the gain of protons; reduction is the loss of protons.
- D) Oxidation is the loss of protons; reduction is the gain of protons.
Correct Answer: B) Oxidation is the loss of electrons; reduction is the gain of electrons.
- In a redox reaction, which element is typically oxidized?
- A) The element that gains electrons
- B) The element that loses electrons
- C) The element with the highest atomic number
- D) The element with the lowest atomic number
Correct Answer: B) The element that loses electrons.
- Cerimetry is a redox titration method. What is the cerimetric titration used to determine?
- A) Concentration of cerium ions
- B) Concentration of reducing agents
- C) Concentration of oxidizing agents
- D) Concentration of transition metals
Correct Answer: B) Concentration of reducing agents.
- Iodimetry is a type of redox titration. What is the primary purpose of iodimetry?
- A) To determine the concentration of iodine ions
- B) To determine the concentration of iodine molecules
- C) To determine the concentration of reducing agents
- D) To determine the concentration of oxidizing agents
Correct Answer: D) To determine the concentration of oxidizing agents.
- In iodometry, what substance is commonly used as the titrant, reacting with the analyte?
- A) Iodine (I2)
- B) Potassium iodide (KI)
- C) Sodium chloride (NaCl)
- D) Sodium thiosulfate (Na2S2O3)
Correct Answer: D) Sodium thiosulfate (Na2S2O3).
- Bromatometry is a redox titration method. What is typically determined in bromatometry?
- A) Concentration of bromine ions
- B) Concentration of reducing agents
- C) Concentration of bromine molecules
- D) Concentration of oxidizing agents
Correct Answer: D) Concentration of oxidizing agents.
- Dichrometry is a redox titration technique. What is commonly used as the titrant in dichrometry?
- A) Potassium dichromate (K2Cr2O7)
- B) Potassium iodide (KI)
- C) Sodium thiosulfate (Na2S2O3)
- D) Bromine (Br2)
Correct Answer: A) Potassium dichromate (K2Cr2O7).
- Titration with potassium iodate is a specific type of redox titration. What is the primary purpose of this titration?
- A) To determine the concentration of iodine ions
- B) To determine the concentration of iodate ions
- C) To determine the concentration of reducing agents
- D) To determine the concentration of oxidizing agents
Correct Answer: B) To determine the concentration of iodate ions.
- What is the chemical symbol for iodine?
- A) I
- B) Ir
- C) Io
- D) In
Correct Answer: A) I.
In a redox titration, what is the substance that undergoes reduction?
- A) Oxidizing agent
- B) Indicator
- C) Titrant
- D) Analyte
Correct Answer: A) Oxidizing agent.
In a redox titration, what is the stoichiometric point also known as?
- A) Endpoint
- B) Equivalence point
- C) Starting point
- D) Midpoint
Correct Answer: B) Equivalence point.
What is the purpose of an indicator in a redox titration?
- A) To react with the analyte
- B) To react with the titrant
- C) To change color near the endpoint
- D) To speed up the reaction
Correct Answer: C) To change color near the endpoint.
Which of the following indicators is commonly used in redox titrations involving iodine or iodide ions?
- A) Phenolphthalein
- B) Methyl orange
- C) Starch
- D) Bromothymol blue
Correct Answer: C) Starch.
In iodometry, what happens to the iodide ions in the presence of an oxidizing agent?
- A) They remain unchanged.
- B) They are reduced to iodine.
- C) They are converted into iodate ions.
- D) They evaporate.
Correct Answer: B) They are reduced to iodine.
What is the standard solution used in cerimetric titrations to determine the concentration of reducing agents?
- A) Potassium dichromate (K2Cr2O7)
- B) Cerium(IV) sulfate (Ce(SO4)2)
- C) Sodium thiosulfate (Na2S2O3)
- D) Potassium iodate (KIO3)
Correct Answer: B) Cerium(IV) sulfate (Ce(SO4)2).
In a redox titration, the titrant is added to the analyte until the equivalence point is reached. What does this signify?
- A) The reaction is complete.
- B) The reaction is just beginning.
- C) The indicator has changed color.
- D) The analyte is in excess.
Correct Answer: A) The reaction is complete.
In redox titrations, what is the role of the reference electrode?
- A) To measure the pH of the solution
- B) To maintain a constant temperature
- C) To monitor the color change of the indicator
- D) To provide a stable potential for the titration
Correct Answer: D) To provide a stable potential for the titration.
What is the chemical symbol for the sulfate ion commonly used in redox titrations?
- A) S
- B) SO3
- C) SO4
- D) S2O3
Correct Answer: C) SO4.
- In dichrometry, which ion is reduced to chromium(III) ions during the titration process?
- A) Chromium(IV) ions
- B) Hydroxide ions
- C) Hydrogen ions
- D) Chloride ions
Correct Answer: A) Chromium(IV) ions.
In redox titrations, what is the term for the difference between the volume of titrant required to reach the endpoint and the volume of titrant used for the blank titration?
- A) Indicator volume
- B) Equivalence volume
- C) Titration volume
- D) Blank volume
Correct Answer: B) Equivalence volume.
- What is the primary purpose of titration with potassium iodate in redox titrations?
- A) To determine the concentration of iodine ions
- B) To determine the concentration of iodate ions
- C) To determine the concentration of reducing agents
- D) To determine the concentration of oxidizing agents
Correct Answer: B) To determine the concentration of iodate ions.
In redox titrations involving iodine or iodide ions, what substance is commonly used as the titrant?
- A) Potassium iodate (KIO3)
- B) Potassium dichromate (K2Cr2O7)
- C) Sodium thiosulfate (Na2S2O3)
- D) Cerium(IV) sulfate (Ce(SO4)2)
Correct Answer: A) Potassium iodate (KIO3).
In a redox titration involving potassium dichromate as the titrant, what is typically used as the indicator to signal the endpoint?
- A) Phenolphthalein
- B) Methyl orange
- C) Starch
- D) Bromothymol blue
Correct Answer: C) Starch.
What is the function of an indicator in a redox titration?
- A) To react with the analyte
- B) To react with the titrant
- C) To change color near the endpoint
- D) To speed up the reaction
Correct Answer: C) To change color near the endpoint.
In redox titrations, what is the term for the point at which the reactants have completely reacted, and no more reaction occurs upon further addition of titrant?
- A) Equivalence point
- B) Endpoint
- C) Midpoint
- D) Titration point
Correct Answer: A) Equivalence point.
What is the role of a reference electrode in redox titrations?
- A) To measure the pH of the solution
- B) To maintain a constant temperature
- C) To monitor the color change of the indicator
- D) To provide a stable potential for the titration
Correct Answer: D) To provide a stable potential for the titration.
In iodometry, what happens to the iodide ions when they react with an oxidizing agent?
- A) They remain unchanged.
- B) They are reduced to iodine.
- C) They are converted into iodate ions.
- D) They evaporate.
Correct Answer: B) They are reduced to iodine.
Which of the following is commonly used as a reducing agent in redox titrations?
- A) Potassium permanganate (KMnO4)
- B) Sodium thiosulfate (Na2S2O3)
- C) Potassium dichromate (K2Cr2O7)
- D) Hydrochloric acid (HCl)
Correct Answer: B) Sodium thiosulfate (Na2S2O3).
In redox titrations, what is the term for the volume of titrant required to reach the endpoint?
- A) Indicator volume
- B) Equivalence volume
- C) Titration volume
- D) Blank volume
Correct Answer: B) Equivalence volume.
Why is the choice of indicator crucial in redox titrations?
- A) Indicators determine the choice of titrant.
- B) Indicators can introduce errors in pH measurements.
- C) Indicators must be dissolved in water for accuracy.
- D) Indicators signal the endpoint of the titration.
Correct Answer: D) Indicators signal the endpoint of the titration.
When using potassium dichromate (K2Cr2O7) as the titrant in a redox titration, what is the typical reaction involved at the equivalence point?
- A) Reduction of chromium ions
- B) Reduction of dichromate ions to chromium(III) ions
- C) Oxidation of dichromate ions to chromate ions
- D) Formation of a complex with the analyte
Correct Answer: B) Reduction of dichromate ions to chromium(III) ions.
- In redox titrations, why is it important to carefully add the titrant near the endpoint?
- A) To speed up the reaction
- B) To avoid overshooting the endpoint
- C) To prevent the formation of side products
- D) To ensure a consistent color change
Correct Answer: B) To avoid overshooting the endpoint.
What is the primary application of iodometry in analytical chemistry?
- A) Determining the concentration of iodine in solution
- B) Determining the concentration of reducing agents
- C) Determining the concentration of oxidizing agents
- D) Determining the pH of a solution
Correct Answer: B) Determining the concentration of reducing agents.
In redox titrations, what is the role of the titrant?
- A) To react with the indicator
- B) To change color near the endpoint
- C) To provide a stable potential for the titration
- D) To react with the analyte to complete the reaction
Correct Answer: D) To react with the analyte to complete the reaction.
Which chemical species is often used as the indicator in cerimetric titrations?
- A) Potassium dichromate (K2Cr2O7)
- B) Cerium(IV) sulfate (Ce(SO4)2)
- C) Sodium thiosulfate (Na2S2O3)
- D) Starch
Correct Answer: D) Starch.
In a redox titration involving potassium permanganate (KMnO4) as the titrant, what is the color change indicating the endpoint?
- A) From purple to colorless
- B) From colorless to pink
- C) From pink to colorless
- D) From green to brown
Correct Answer: C) From pink to colorless.
What does the stoichiometric coefficient in a balanced redox equation represent?
- A) The number of electrons transferred
- B) The concentration of the titrant
- C) The color change at the endpoint
- D) The volume of the analyte
Correct Answer: A) The number of electrons transferred.
In a redox titration, why is it important to record the volume of titrant added at the equivalence point?
- A) To calculate the molarity of the analyte
- B) To determine the molar mass of the titrant
- C) To identify the indicator used
- D) To calculate the moles of the analyte
Correct Answer: D) To calculate the moles of the analyte.
Which of the following is a common reducing agent used in iodimetry?
- A) Potassium iodate (KIO3)
- B) Sodium thiosulfate (Na2S2O3)
- C) Potassium dichromate (K2Cr2O7)
- D) Hydrochloric acid (HCl)
Correct Answer: B) Sodium thiosulfate (Na2S2O3).
In redox titrations, what is the purpose of performing a blank titration?
- A) To determine the concentration of the titrant
- B) To establish a baseline for color change
- C) To confirm the accuracy of the titration apparatus
- D) To calculate the moles of the titrant used
Correct Answer: B) To establish a baseline for color change.
In cerimetry, cerium(IV) ions (Ce⁴⁺) are reduced to cerium(III) ions (Ce³⁺) during the titration. Which of the following substances is commonly used as a reducing agent in cerimetry?
- A) Potassium permanganate (KMnO₄)
- B) Sodium thiosulfate (Na₂S₂O₃)
- C) Potassium dichromate (K₂Cr₂O₇)
- D) Sodium hydroxide (NaOH)
Correct Answer: B) Sodium thiosulfate (Na₂S₂O₃).
Bromatometry is a redox titration method often used to determine the concentration of bromine or bromide ions. What is the typical reaction occurring at the endpoint in bromatometry?
- A) Reduction of bromine ions to bromide ions
- B) Oxidation of bromide ions to bromine ions
- C) Formation of a bromine complex
- D) Reduction of bromine ions to bromate ions
Correct Answer: B) Oxidation of bromide ions to bromine ions.
In iodometry, a common redox reaction involves the titration of iodine ions (I⁻) with an oxidizing agent. What is the primary application of iodometry in chemistry?
- A) Determining the concentration of iodine ions in solution
- B) Determining the concentration of reducing agents
- C) Determining the concentration of oxidizing agents
- D) Determining the concentration of hydroxide ions
Correct Answer: B) Determining the concentration of reducing agents.
Dichrometry, using potassium dichromate (K₂Cr₂O₇) as the titrant, often involves the determination of reducing agents. What is the chemical change that occurs at the equivalence point in dichrometry?
- A) Formation of chromium ions (Cr⁺⁺⁺)
- B) Formation of dichromate ions (Cr₂O₇⁻²)
- C) Formation of chromate ions (CrO₄⁻²)
- D) Formation of chromium(III) ions (Cr³⁺)
Correct Answer: D) Formation of chromium(III) ions (Cr³⁺).
Cerimetry is a redox titration method used to determine the concentration of reducing agents. What is the role of cerium(IV) ions (Ce⁴⁺) in cerimetry?
- A) To serve as the indicator
- B) To act as a reference electrode
- C) To oxidize the analyte
- D) To reduce the analyte
Correct Answer: C) To oxidize the analyte.
In redox titrations, why is it essential to perform a blank titration?
- A) To confirm the stoichiometry of the reaction
- B) To establish a baseline for color change
- C) To determine the concentration of the titrant
- D) To calculate the molar mass of the analyte
Correct Answer: B) To establish a baseline for color change.
What does the term “end point” refer to in a redox titration?
- A) The volume of titrant required to reach the equivalence point
- B) The volume of titrant at which the color change occurs
- C) The initial point of the titration
- D) The point where the reaction reaches equilibrium
Correct Answer: B) The volume of titrant at which the color change occurs.
What is the purpose of using a reference electrode in redox titrations?
- A) To measure the pH of the solution
- B) To maintain a constant temperature
- C) To monitor the color change of the indicator
- D) To provide a stable potential for the titration
Correct Answer: D) To provide a stable potential for the titration.
Which of the following is commonly used as an indicator in iodometry to signal the endpoint of the titration?
- A) Starch
- B) Phenolphthalein
- C) Methyl orange
- D) Bromothymol blue
Correct Answer: A) Starch.
In redox titrations, why is it crucial to add the titrant slowly and with constant swirling during the latter stages of the titration near the endpoint?
- A) To speed up the reaction
- B) To avoid overshooting the endpoint
- C) To reduce the volume of the titrant used
- D) To ensure the accuracy of the titration
Correct Answer: B) To avoid overshooting the endpoint.
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