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Basicity
Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push electrons). Phenylamine weaker (lone pair pulled into the ring named). Salts: RNH3+ Cl- from HCl. Meaning: stronger base = more ready to take H+. Not a drain-cleaner recipe. Amines accept H+ better than ammonia — aliphatic more basic than N
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Basicity
What is it?
Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push electrons). Phenylamine weaker (lone pair pulled into the ring named). Salts: RNH3+ Cl- from HCl. Meaning: stronger base = more ready to take H+. Not a drain-cleaner recipe. Amines accept H+ better than ammonia — aliphatic more basic than NH3; aniline less (delocalisation). Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
In simple words
- Amines accept H+ (Bronsted) using the lone pair.
- 1. WITH ACIDS: RNH2 + HCl -> RNH3+ Cl-.
- 2. STRENGTH ORDER: Typical school: aliphatic amine > NH3 > phenylamine.
- Exam reminder: Exam basicity: amines are weak bases (lone pair) aliphatic usually > ammonia phenylamine weaker (pair into the ring) if asked
Important terms
BASICITY: Amines accept H+ (Bronsted) using the lone pair.
1. WITH ACIDS: RNH2 + HCl -> RNH3+ Cl-.
2. STRENGTH ORDER: Typical school: aliphatic amine > NH3 > phenylamine.
What you should learn
- Explain basicity in simple chemical language.
- Connect 1. with acids with 2. strength order using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Examples
- Litmus blue
- Ionic salt
- Soluble
WITH ACIDS
RNH2 + HCl -> RNH3+ Cl-. White ionic salt. Unlike alcohols. CO2 not the test here (that was carboxylic). Basicity order school: aliphatic 3>2>1> NH3 > aniline roughly.
STRENGTH ORDER
Typical school: aliphatic amine > NH3 > phenylamine. Explain with availability of the pair. pKb / pKa of conjugate if tables given. Salt formation with HCl gives ammonium chloride — water soluble.
Recommended for Class 11
Full school-level explanation
Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push electrons). Phenylamine weaker (lone pair pulled into the ring named). Salts: RNH3+ Cl- from HCl. Meaning: stronger base = more ready to take H+. Not a drain-cleaner recipe. Amines accept H+ better than ammonia — aliphatic more basic than NH3; aniline less (delocalisation). Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
In water, then compare:
WHAT — BASICITY
Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push electrons). Phenylamine weaker (lone pair pulled into the ring named). Salts: RNH3+ Cl- from HCl. Meaning: stronger base = more ready to take H+. Not a drain-cleaner recipe. Amines accept H+ better than ammonia — aliphatic more basic than NH3; aniline less (delocalisation). Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
WHY — Why this topic matters
BASICITY is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
WITH ACIDS: RNH2 + HCl -> RNH3+ Cl-. White ionic salt. Unlike alcohols. CO2 not the test here (that was carboxylic). Basicity order school: aliphatic 3>2>1> NH3 > aniline roughly. Examples: Litmus blue; Ionic salt; Soluble. STRENGTH ORDER: Typical school: aliphatic amine > NH3 > phenylamine. Explain with availability of the pair. pKb / pKa of conjugate if tables given. Salt formation with HCl gives ammonium chloride — water soluble. Examples: Alkyl donors named; Ring withdraws named; Not a dose. Exam basicity: amines are weak bases (lone pair) aliphatic usually > ammonia phenylamine weaker (pair into the ring) if asked
WITH ACIDS
RNH2 + HCl -> RNH3+ Cl-. White ionic salt. Unlike alcohols. CO2 not the test here (that was carboxylic). Basicity order school: aliphatic 3>2>1> NH3 > aniline roughly.
Remember
- salt with HCl
Examples
- Litmus blue
- Ionic salt
- Soluble
STRENGTH ORDER
Typical school: aliphatic amine > NH3 > phenylamine. Explain with availability of the pair. pKb / pKa of conjugate if tables given. Salt formation with HCl gives ammonium chloride — water soluble.
Remember
- pair more available
Examples
- Alkyl donors named
- Ring withdraws named
- Not a dose
Remember
- lone pair takes H+
- phenylamine weaker if named
- pair availability
- strength only
- salt with HCl
- pair more available
- lone pair takes H+
- phenylamine weaker if named
How the ideas connect
Exam basicity: amines are weak bases (lone pair) aliphatic usually > ammonia phenylamine weaker (pair into the ring) if asked
Deeper understanding
Go beyond memorising Basicity. Connect the definition to reasons, relationships, exceptions, and exam wording.
How the ideas connect
Exam basicity: amines are weak bases (lone pair) aliphatic usually > ammonia phenylamine weaker (pair into the ring) if asked
Common mistakes
Exam focus
Core Idea
1. WITH ACIDS
2. STRENGTH ORDER
Exam Example
Exam focus
Quick revision
- lone pair takes H+
- phenylamine weaker if named
- pair availability
- strength only
- BASICITY: Amines accept H+ (Bronsted) using the lone pair.
- 1. WITH ACIDS: RNH2 + HCl -> RNH3+ Cl-.
Base strength. No illicit stimulant chemistry.
For long answers on Basicity: define clearly → explain the main parts → give one example → state one exam caution.
Exam Focus
Exam Focus
Important points
- lone pair takes H+
- phenylamine weaker if named
- pair availability
- strength only
Important formulas
- lone pair takes H+
- phenylamine weaker if named
- pair availability
Common exam traps
- Do not confuse 1. WITH ACIDS with 2. STRENGTH ORDER; state the difference before giving an example.
- Writing only “lone pair takes H+” is not enough. Explain what it means in a complete sentence.
Long question structure
Definition → key parts → example → exam caution
Common Mistakes
Common Mistakes
- Mistake
Do not confuse 1. WITH ACIDS with 2. STRENGTH ORDER; state the difference before giving an example.
- Mistake
Writing only “lone pair takes H+” is not enough. Explain what it means in a complete sentence.
- Mistake
Base strength. No illicit stimulant chemistry.
- Mistake
Base strength. No illicit stimulant chemistry.
Revision Zone
60-Second Revision
Quick cues from this topic — use them for last-minute revision.
lone pair takes H+
phenylamine weaker if named
pair availability
strength only
Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push
- Definition
- Amines accept H+ (Bronsted) using the lone pair. Aqueous: weakly alkaline, turn litmus blue. Alkyl amines often a bit stronger bases than NH3 (book: alkyl push
- Example
- Litmus blue
- Critical warning
- Do not confuse 1. WITH ACIDS with 2. STRENGTH ORDER; state the difference before giving an example.
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Exam Practice
Define
Q1. Define Basicity.
Explain
Q2. Explain: WITH ACIDS.
Example
Q3. Give one clear example of Basicity and say why it fits.
Mistake
Q4. State one common mistake students make about Basicity.
Exam note
Q5. Write a short exam note on Basicity: definition, two points, one example.
Sources & References
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.