ChemistryChapter 9: Halogenoalkanes
9.4 Reaction with aqueous silver nitrate
The main idea is that when a halogenoalkane reacts with aqueous silver nitrate, the silver ion (Ag\(^+\)) acts as a nucleophile
Explanation level
In the previous sections, we explored the mechanisms of nucleophilic substitution (SN1 and SN2) and elimination reactions of halogenoalkanes. Now, we will look at a specific and very useful reaction that helps chemists identify the halogen present in a halogenoalkane and compare their reactivities: the reaction with aqueous silver nitrate (AgNO3).
Main Idea
The main idea is that when a halogenoalkane reacts with aqueous silver nitrate, the silver ion (Ag+) acts as a nucleophile (or more precisely, a Lewis acid that coordinates to the halide) and abstracts the halide ion (X-) from the halogenoalkane. This forms a precipitate of silver halide (AgX). The rate at which this precipitate forms and the colour of the precipitate can be used to identify the halogen and compare the reactivity of different halogenoalkanes.
Core Concept
The core concept is that the rate of formation of the silver halide precipitate depends on the rate of the nucleophilic substitution reaction. The rate of substitution is determined by the strength of the carbon-halogen (C-X) bond and the stability of the resulting carbocation (in an SN1 mechanism). The C-X bond strength decreases down the halogen group (C-F > C-Cl > C-Br > C-I), so iodoalkanes react the fastest, and fluoroalkanes react the slowest (or not at all). The colour of the silver halide precipitate also varies: AgCl is white, AgBr is cream, and AgI is yellow.
Detailed Explanation
The textbook describes the reaction of haloalkanes with aqueous silver nitrate.
The Reaction
When a haloalkane reacts with aqueous silver nitrate (AgNO3), the silver ion (Ag+) in the solution is exchanged with the halide ion (X-) in the haloalkane. A precipitate of silver halide (AgX) is formed.
The general equation is: R-X + AgNO_3 \rightarrow R-NO_3 + AgX where X = Cl, Br, I.
- Alkyl fluoride does not react readily with AgNO3 because the C-F bond is very strong, so the fluoride ion is not displaced.
- The reaction is a nucleophilic substitution where the silver ion (Ag+) effectively acts as the nucleophile (or assists in the removal of the halide).
- The colour of the precipitate depends on the halogen present.
Colours of Silver Halide Precipitates
- AgCl: White precipitate, which is soluble in NH4OH solution.
- AgBr: Cream-coloured precipitate, which is partially soluble in NH4OH solution.
- AgI: Yellow precipitate, which is insoluble in NH4OH solution.
Identifying the Halogen and Comparing Reactivity
This reaction is used as a test for halogenoalkanes and to compare their reactivity.
- White precipitate → Chlorine.
- Cream precipitate → Bromine.
- Yellow precipitate → Iodine.
2. Comparing Reactivity: The rate at which the precipitate forms indicates the reactivity of the halogenoalkane. The reactivity order is: R-I > R-Br > R-Cl > R-F - Iodoalkanes react the fastest because the C-I bond is the weakest. - Chloroalkanes react more slowly because the C-Cl bond is stronger. - Fluoroalkanes do not react under these conditions because the C-F bond is very strong.
The difference in reactivity is primarily due to the strength of the C-X bond (the weaker the bond, the more reactive the halogenoalkane) and the stability of the halide ion (larger halide ions are more polarizable and better leaving groups).
Intermediate Level
The reaction with aqueous silver nitrate is a nucleophilic substitution reaction used to test for and compare the reactivity of halogenoalkanes. The silver ion (Ag+) assists in the removal of the halide ion (X-) from the halogenoalkane, forming an insoluble silver halide precipitate (AgX). The colour of the precipitate identifies the halogen: AgCl is white, AgBr is cream, and AgI is yellow. The rate of precipitate formation reflects the reactivity of the halogenoalkane, which is determined by the strength of the C-X bond. The reactivity order is R-I > R-Br > R-Cl > R-F. Fluoroalkanes do not react because the C-F bond is too strong. The solubility of the precipitates in ammonium hydroxide also helps in identification: AgCl is soluble, AgBr is partially soluble, and AgI is insoluble.
Important Points
- - Reaction: Halogenoalkane + AgNO3 → AgX precipitate.
- - Colours: AgCl (white), AgBr (cream), AgI (yellow).
- - Solubility in NH4OH: AgCl (soluble), AgBr (partially soluble), AgI (insoluble).
- - Reactivity order: R-I > R-Br > R-Cl > R-F.
- - Fluoroalkanes do not react (strong C-F bond).
- - Ag+ acts as a Lewis acid/nucleophile to assist the departure of the halide.
- - The rate of precipitate formation indicates the reactivity of the halogenoalkane.
Remember
- - AgCl: White, soluble in NH4OH.
- - AgBr: Cream, partially soluble in NH4OH.
- - AgI: Yellow, insoluble in NH4OH.
- - Reactivity: I > Br > Cl > F.
- - Fluoroalkanes don't react (too strong C-F bond).
- - Ag+ assists the removal of halide.
- - The test is used to identify the halogen.
Common Mistakes
- - Forgetting that fluoroalkanes do not react. The C-F bond is too strong to be broken under these conditions.
- - Confusing the colours of the precipitates. AgCl = white, AgBr = cream, AgI = yellow.
- - Assuming that all precipitates have the same solubility. AgCl is soluble in NH4OH, AgBr is partially soluble, and AgI is insoluble.
- - Thinking that the reactivity order is determined only by bond strength. While bond strength is a major factor, the stability of the leaving group and the mechanism also play a role.
- - Not recognizing the role of Ag+. The silver ion is not a simple nucleophile; it assists in the removal of the halide by forming an insoluble precipitate.
Quick Revision
The reaction of halogenoalkanes with aqueous silver nitrate is a nucleophilic substitution that forms a silver halide precipitate (AgX). This reaction is used to identify the halogen and compare the reactivity of halogenoalkanes. The colour of the precipitate identifies the halogen: AgCl (white), AgBr (cream), and AgI (yellow). The solubility of the precipitates in ammonium hydroxide also helps: AgCl is soluble, AgBr is partially soluble, and AgI is insoluble. The reactivity order of halogenoalkanes is R-I > R-Br > R-Cl > R-F, based on the strength of the C-X bond. Fluoroalkanes do not react because the C-F bond is too strong. The rate of precipitate formation indicates the reactivity of the halogenoalkane.
60-Second Revision
Halogenoalkanes react with aqueous AgNO3 to form a silver halide precipitate (AgX). The colour identifies the halogen: AgCl (white), AgBr (cream), AgI (yellow). The reactivity order is R-I > R-Br > R-Cl > R-F. Fluoroalkanes do not react. The solubility of the precipitate in NH4OH also helps: AgCl is soluble, AgBr is partially soluble, and AgI is insoluble.
Frequently Asked Questions (FAQs)
Q1. What is the reaction between a halogenoalkane and aqueous silver nitrate? Answer: When a halogenoalkane reacts with aqueous silver nitrate (AgNO3), the silver ion (Ag+) assists in the removal of the halide ion (X-) from the halogenoalkane, forming an insoluble silver halide precipitate (AgX). The general equation is: R-X + AgNO3 → R-NO3 + AgX
- AgCl: White precipitate.
- AgBr: Cream-coloured precipitate.
- AgI: Yellow precipitate.
- AgCl: Soluble in NH4OH.
- AgBr: Partially soluble in NH4OH.
- AgI: Insoluble in NH4OH.
Q4. Why does alkyl fluoride not react with silver nitrate? Answer: Alkyl fluoride does not react with silver nitrate because the carbon-fluorine (C-F) bond is very strong and not easily broken. The fluoride ion is a poor leaving group, so it is not displaced by the silver ion.
- Q5. What is the order of reactivity of halogenoalkanes with aqueous silver nitrate?
- Answer: The reactivity order is:
- R-I > R-Br > R-Cl > R-F
- This is because the C-X bond strength decreases down the group (C-F > C-Cl > C-Br > C-I), so the halide becomes easier to displace.
- Identifying the halogen: The colour of the precipitate identifies the halogen.
- Comparing reactivity: The rate of precipitate formation indicates the reactivity of the halogenoalkane, which is related to the strength of the C-X bond.
Q7. What is the role of the silver ion in the reaction? Answer: The silver ion (Ag+) acts as a Lewis acid and coordinates to the halide ion (X-), facilitating its departure from the halogenoalkane. The precipitation of the insoluble silver halide (AgX) drives the reaction forward.
Q8. Why is AgBr partially soluble in NH4OH while AgCl is fully soluble and AgI is insoluble? Answer: The solubility depends on the ability of NH3 to form a complex with the silver ion, [Ag(NH3)2]+. AgCl is the most soluble because the chloride ion is the smallest and least polarizable, allowing the complex to form easily. AgBr is less soluble because the bromide ion is larger and more polarizable. AgI is the least soluble because the iodide ion is very large and polarizable, making the complex formation unfavorable.
Q9. Can this reaction be used to distinguish between primary, secondary, and tertiary halogenoalkanes? Answer: The reaction with AgNO3 is primarily used to identify the halogen and compare the reactivity of different halogens, not to distinguish between primary, secondary, and tertiary halogenoalkanes. However, the rate of precipitation can be influenced by the substrate structure: tertiary halogenoalkanes react faster (via SN1) than primary halogenoalkanes (via SN2). But the primary use is for halogen identification.
Multiple Choice Questions (MCQs)
- Q1. What is the colour of the precipitate formed when chloroethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: The precipitate is silver chloride (AgCl), which is white.
- Q2. What is the colour of the precipitate formed when bromoethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: The precipitate is silver bromide (AgBr), which is cream-coloured.
- Q3. What is the colour of the precipitate formed when iodoethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: The precipitate is silver iodide (AgI), which is yellow.
- Q4. Which of the following halogenoalkanes is the most reactive with aqueous silver nitrate?
- A. Fluoroethane
- B. Chloroethane
- C. Bromoethane
- D. Iodoethane
- Correct Answer: D
- Explanation: Iodoethane is the most reactive because the C-I bond is the weakest.
- Q5. Which of the following halogenoalkanes does not react readily with aqueous silver nitrate?
- A. Fluoroethane
- B. Chloroethane
- C. Bromoethane
- D. Iodoethane
- Correct Answer: A
- Explanation: Fluoroethane does not react readily because the C-F bond is very strong.
- Q6. What is the general equation for the reaction of a halogenoalkane with aqueous silver nitrate?
- A. R-X + AgNO3 → R-NO3 + AgX
- B. R-X + AgNO3 → R-Ag + XNO3
- C. R-X + AgNO3 → R-XNO3 + Ag
- D. R-X + AgNO3 → R-OH + AgX
- Correct Answer: A
- Explanation: The reaction forms a silver halide precipitate.
- Q7. Which of the following is a correct order of reactivity of halogenoalkanes with AgNO3?
- A. R-F > R-Cl > R-Br > R-I
- B. R-I > R-Br > R-Cl > R-F
- C. R-Cl > R-Br > R-I > R-F
- D. R-Br > R-I > R-Cl > R-F
- Correct Answer: B
- Explanation: The reactivity order is R-I > R-Br > R-Cl > R-F.
- Q8. What is the role of the silver ion in the reaction with halogenoalkanes?
- A. It acts as a nucleophile.
- B. It acts as a base.
- C. It assists in the removal of the halide ion.
- D. It acts as a solvent.
- Correct Answer: C
- Explanation: The silver ion assists in the removal of the halide ion by forming an insoluble precipitate.
- Q9. Which of the following silver halides is soluble in ammonium hydroxide?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble in ammonium hydroxide.
- Q10. Which of the following silver halides is insoluble in ammonium hydroxide?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble in ammonium hydroxide.
Multiple Choice Questions (MCQs)
- Q1. What is the colour of the precipitate formed when chloroethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: The precipitate is silver chloride (AgCl), which is white.
- Q2. What is the colour of the precipitate formed when bromoethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: The precipitate is silver bromide (AgBr), which is cream-coloured.
- Q3. What is the colour of the precipitate formed when iodoethane reacts with aqueous silver nitrate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: The precipitate is silver iodide (AgI), which is yellow.
- Q4. Which of the following halogenoalkanes is the most reactive with aqueous silver nitrate?
- A. Fluoroethane
- B. Chloroethane
- C. Bromoethane
- D. Iodoethane
- Correct Answer: D
- Explanation: Iodoethane is the most reactive.
- Q5. Which of the following halogenoalkanes does not react readily with aqueous silver nitrate?
- A. Fluoroethane
- B. Chloroethane
- C. Bromoethane
- D. Iodoethane
- Correct Answer: A
- Explanation: Fluoroethane does not react readily.
- Q6. What is the general equation for the reaction of a halogenoalkane with aqueous silver nitrate?
- A. R-X + AgNO3 → R-NO3 + AgX
- B. R-X + AgNO3 → R-Ag + XNO3
- C. R-X + AgNO3 → R-XNO3 + Ag
- D. R-X + AgNO3 → R-OH + AgX
- Correct Answer: A
- Explanation: The reaction forms a silver halide precipitate.
- Q7. Which of the following is a correct order of reactivity of halogenoalkanes with AgNO3?
- A. R-F > R-Cl > R-Br > R-I
- B. R-I > R-Br > R-Cl > R-F
- C. R-Cl > R-Br > R-I > R-F
- D. R-Br > R-I > R-Cl > R-F
- Correct Answer: B
- Explanation: The reactivity order is R-I > R-Br > R-Cl > R-F.
- Q8. What is the role of the silver ion in the reaction with halogenoalkanes?
- A. It acts as a nucleophile.
- B. It acts as a base.
- C. It assists in the removal of the halide ion.
- D. It acts as a solvent.
- Correct Answer: C
- Explanation: The silver ion assists in the removal of the halide ion.
- Q9. Which of the following silver halides is soluble in ammonium hydroxide?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble in ammonium hydroxide.
- Q10. Which of the following silver halides is insoluble in ammonium hydroxide?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble in ammonium hydroxide.
Multiple Choice Questions (MCQs)
- Q1. What is the colour of the AgCl precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: AgCl is a white precipitate.
- Q2. What is the colour of the AgBr precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: AgBr is a cream-coloured precipitate.
- Q3. What is the colour of the AgI precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: AgI is a yellow precipitate.
- Q4. Which halogenoalkane is the most reactive with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: D
- Explanation: R-I is the most reactive.
- Q5. Which halogenoalkane is the least reactive with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: A
- Explanation: R-F is the least reactive (does not react readily).
- Q6. What is the role of Ag+ in the reaction?
- A. It acts as a nucleophile.
- B. It assists in the removal of the halide ion.
- C. It acts as a base.
- D. It acts as a solvent.
- Correct Answer: B
- Explanation: Ag+ assists in the removal of the halide ion.
- Q7. Which silver halide is soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble in NH4OH.
- Q8. Which silver halide is partially soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: B
- Explanation: AgBr is partially soluble in NH4OH.
- Q9. Which silver halide is insoluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble in NH4OH.
- Q10. Why does R-F not react with AgNO3?
- A. Because the C-F bond is strong.
- B. Because the C-F bond is weak.
- C. Because F is a good leaving group.
- D. Because F is a strong nucleophile.
- Correct Answer: A
- Explanation: The C-F bond is very strong, so it is not easily broken.
Multiple Choice Questions (MCQs)
- Q1. What is the colour of the AgCl precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: AgCl is a white precipitate.
- Q2. What is the colour of the AgBr precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: AgBr is a cream-coloured precipitate.
- Q3. What is the colour of the AgI precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: AgI is a yellow precipitate.
- Q4. Which halogenoalkane is the most reactive with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: D
- Explanation: R-I is the most reactive.
- Q5. Which halogenoalkane is the least reactive with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: A
- Explanation: R-F is the least reactive.
- Q6. What is the role of Ag+ in the reaction?
- A. It acts as a nucleophile.
- B. It assists in the removal of the halide ion.
- C. It acts as a base.
- D. It acts as a solvent.
- Correct Answer: B
- Explanation: Ag+ assists in the removal of the halide ion.
- Q7. Which silver halide is soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble in NH4OH.
- Q8. Which silver halide is partially soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: B
- Explanation: AgBr is partially soluble in NH4OH.
- Q9. Which silver halide is insoluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble in NH4OH.
- Q10. Why does R-F not react with AgNO3?
- A. Because the C-F bond is strong.
- B. Because the C-F bond is weak.
- C. Because F is a good leaving group.
- D. Because F is a strong nucleophile.
- Correct Answer: A
- Explanation: The C-F bond is very strong, so it is not easily broken.
Multiple Choice Questions (MCQs)
- Q1. Which of the following is a correct statement about the reaction of halogenoalkanes with AgNO3?
- A. It is an electrophilic substitution.
- B. It is a nucleophilic substitution.
- C. It is an addition reaction.
- D. It is an elimination reaction.
- Correct Answer: B
- Explanation: It is a nucleophilic substitution reaction.
- Q2. What is the product of the reaction between a halogenoalkane and AgNO3?
- A. A silver halide precipitate.
- B. An alcohol.
- C. An alkene.
- D. An alkane.
- Correct Answer: A
- Explanation: The product is a silver halide precipitate.
- Q3. Which halogenoalkane reacts the fastest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: D
- Explanation: R-I reacts the fastest.
- Q4. Which halogenoalkane reacts the slowest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: A
- Explanation: R-F reacts the slowest (or not at all).
- Q5. What is the colour of the AgCl precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: AgCl is white.
- Q6. What is the colour of the AgBr precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: AgBr is cream.
- Q7. What is the colour of the AgI precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: AgI is yellow.
- Q8. Which silver halide is soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble.
- Q9. Which silver halide is insoluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble.
- Q10. What is the role of Ag+ in the reaction?
- A. It acts as a nucleophile.
- B. It assists in the removal of the halide ion.
- C. It acts as a base.
- D. It acts as a solvent.
- Correct Answer: B
- Explanation: Ag+ assists in the removal of the halide ion.
Multiple Choice Questions (MCQs)
- Q1. Which of the following is a correct statement about the reaction of halogenoalkanes with AgNO3?
- A. It is an electrophilic substitution.
- B. It is a nucleophilic substitution.
- C. It is an addition reaction.
- D. It is an elimination reaction.
- Correct Answer: B
- Explanation: It is a nucleophilic substitution reaction.
- Q2. What is the product of the reaction between a halogenoalkane and AgNO3?
- A. A silver halide precipitate.
- B. An alcohol.
- C. An alkene.
- D. An alkane.
- Correct Answer: A
- Explanation: The product is a silver halide precipitate.
- Q3. Which halogenoalkane reacts the fastest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: D
- Explanation: R-I reacts the fastest.
- Q4. Which halogenoalkane reacts the slowest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: A
- Explanation: R-F reacts the slowest.
- Q5. What is the colour of the AgCl precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: AgCl is white.
- Q6. What is the colour of the AgBr precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: AgBr is cream.
- Q7. What is the colour of the AgI precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: AgI is yellow.
- Q8. Which silver halide is soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble.
- Q9. Which silver halide is insoluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble.
- Q10. What is the role of Ag+ in the reaction?
- A. It acts as a nucleophile.
- B. It assists in the removal of the halide ion.
- C. It acts as a base.
- D. It acts as a solvent.
- Correct Answer: B
- Explanation: Ag+ assists in the removal of the halide ion.
Multiple Choice Questions (MCQs)
- Q1. Which of the following is a correct statement about the reaction of halogenoalkanes with AgNO3?
- A. It is an electrophilic substitution.
- B. It is a nucleophilic substitution.
- C. It is an addition reaction.
- D. It is an elimination reaction.
- Correct Answer: B
- Explanation: It is a nucleophilic substitution reaction.
- Q2. What is the product of the reaction between a halogenoalkane and AgNO3?
- A. A silver halide precipitate.
- B. An alcohol.
- C. An alkene.
- D. An alkane.
- Correct Answer: A
- Explanation: The product is a silver halide precipitate.
- Q3. Which halogenoalkane reacts the fastest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: D
- Explanation: R-I reacts the fastest.
- Q4. Which halogenoalkane reacts the slowest with AgNO3?
- A. R-F
- B. R-Cl
- C. R-Br
- D. R-I
- Correct Answer: A
- Explanation: R-F reacts the slowest.
- Q5. What is the colour of the AgCl precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: A
- Explanation: AgCl is white.
- Q6. What is the colour of the AgBr precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: B
- Explanation: AgBr is cream.
- Q7. What is the colour of the AgI precipitate?
- A. White
- B. Cream
- C. Yellow
- D. Green
- Correct Answer: C
- Explanation: AgI is yellow.
- Q8. Which silver halide is soluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: A
- Explanation: AgCl is soluble.
- Q9. Which silver halide is insoluble in NH4OH?
- A. AgCl
- B. AgBr
- C. AgI
- D. AgF
- Correct Answer: C
- Explanation: AgI is insoluble.
- Q10. What is the role of Ag+ in the reaction?
- A. It acts as a nucleophile.
- B. It assists in the removal of the halide ion.
- C. It acts as a base.
- D. It acts as a solvent.
- Correct Answer: B
- Explanation: Ag+ assists in the removal of the halide ion.
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Revision Zone
Review the key facts, formulas and checks before you move on.9.4 Reaction with aqueous silver nitrate
Sticky Notes · Quick Revision
Key Point 1
- AgCl: White, soluble in NH4OH.
Key Point 2
- AgBr: Cream, partially soluble in NH4OH.
Key Point 3
- AgI: Yellow, insoluble in NH4OH.
Key Point 4
- Reactivity: I > Br > Cl > F.
Key Point 5
- Fluoroalkanes don't react.
Key Point 6
- Ag+ helps remove halide.
Key Point 7
- Test for halogen identification.
Key Point 8
- Rate of precipitation = reactivity.
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