ChemistryChapter 20: Nitrogen Compounds-Amines
Nitrous Acid Reaction (school)
Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions).
Learning objectives
- Explain nitrous acid reaction (school) in simple chemical language.
- Connect 1. 1 aliphatic with 2. aromatic and 2 using equations, observations, or trends where needed.
- Answer a short Federal Board question with the correct terms and a clear reason.
Definition
Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions). Primary aliphatic amine: nitrogen gas, bubbles (unstable diazonium school). Primary aromatic: diazonium ion at ice-cold named, then azo coupling named if in the book. Secondary: yellow oily nitrosamine named as a compound class — some are hazardous; this is a name and a warning, not a how-to. Tertiary: different (often no N2). Meaning: the gas test sorts 1 aliphatic amines in old school schemes. Primary aliphatic amine gives alcohol and N2 gas; secondary nitrosamine named caution. Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
Important terms
- NITROUS ACID REACTION (SCHOOL)
- Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions).
- 1. 1 ALIPHATIC
- Bubbles of N2, alcohol leftover named.
- 2. AROMATIC AND 2
- Ice bath for diazonium (named stability).
Overview
What you would see, then warnings:
1 Aliphatic
Bubbles of N2, alcohol leftover named. A qualitative tell. Not a nitrogen-generator to misuse. Tertiary no reaction at N — distinguishes classes at school level.
Examples Bubbles · Room T · Alcohol named
Aromatic and 2
Ice bath for diazonium (named stability). Coupling to coloured azo (named dyes). Nitrosamines: toxic slogan, no preparation for use. These notes stop at the name. Aniline + nitrous acid gives diazonium at low T — dye chemistry link named.
Examples Ice named · Azo colour named · No dye plant
WHAT — NITROUS ACID REACTION (SCHOOL)
Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions). Primary aliphatic amine: nitrogen gas, bubbles (unstable diazonium school). Primary aromatic: diazonium ion at ice-cold named, then azo coupling named if in the book. Secondary: yellow oily nitrosamine named as a compound class — some are hazardous; this is a name and a warning, not a how-to. Tertiary: different (often no N2). Meaning: the gas test sorts 1 aliphatic amines in old school schemes. Primary aliphatic amine gives alcohol and N2 gas; secondary nitrosamine named caution. Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
WHY — Why this topic matters
NITROUS ACID REACTION (SCHOOL) 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
1 ALIPHATIC: Bubbles of N2, alcohol leftover named. A qualitative tell. Not a nitrogen-generator to misuse. Tertiary no reaction at N — distinguishes classes at school level. Examples: Bubbles; Room T; Alcohol named. AROMATIC AND 2: Ice bath for diazonium (named stability). Coupling to coloured azo (named dyes). Nitrosamines: toxic slogan, no preparation for use. These notes stop at the name. Aniline + nitrous acid gives diazonium at low T — dye chemistry link named. Examples: Ice named; Azo colour named; No dye plant. Exam 1 aliphatic amine + HNO2: nitrogen gas bubbles amine carbon ends as an alcohol (school) named test, not a gas-making method
In simple words
Named test. No nitrosamine or azo-dye manufacture.
Key points
- 1 aliphatic: N2 bubbles named
- aromatic diazonium ice-cold named
- N2 gas
- cold for Ar-N2+
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Nitrous Acid Reaction (school)
Sticky Notes · Quick Revision
Core Idea
- Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions). Primary aliphatic amine: nitrogen gas, bubbles (unstable diazonium school). Primary aromatic: diazonium ion at ice-cold named, then azo coupling named if in the book. Secondary: yellow oily nitrosamine named as a compound class — some are hazardous; this is a name and a warning, not a how-to. Tertiary: different (often no N2). Meaning: the gas test sorts 1 aliphatic amines in old school schemes. Primary aliphatic amine gives alcohol and N2 gas; secondary nitrosamine named caution. Nitrous acid behaviour differs for 1, 2, and 3 amines — classify before predicting the product.
1. 1 ALIPHATIC
- Bubbles of N2, alcohol leftover named. A qualitative tell. Not a nitrogen-generator to misuse. Tertiary no reaction at N — distinguishes classes at school level.
- Bubbles
- Room T
- Alcohol named
2. AROMATIC AND 2
- Ice bath for diazonium (named stability). Coupling to coloured azo (named dyes). Nitrosamines: toxic slogan, no preparation for use. These notes stop at the name. Aniline + nitrous acid gives diazonium at low T — dye chemistry link named.
- Ice named
- Azo colour named
- No dye plant
Exam Example
- Exam 1 aliphatic amine + HNO2:
- nitrogen gas bubbles
- amine carbon ends as an alcohol (school)
- named test, not a gas-making method
Common Misconceptions
- Do not confuse 1. 1 ALIPHATIC with 2. AROMATIC AND 2; state the difference before giving an example.
- Writing only “1 aliphatic: N2 bubbles named” is not enough. Explain what it means in a complete sentence.
FBISE Exam Check
- Explain nitrous acid reaction (school), compare its two main parts, and include the correct chemical evidence.
- Named test. No nitrosamine or azo-dye manufacture.
60-second revision
- Nitrous acid HNO2 is made in situ from NaNO2 + mineral acid (named, teacher conditions).
- 1. 1 ALIPHATIC: Bubbles of N2, alcohol leftover named.
- 2. AROMATIC AND 2: Ice bath for diazonium (named stability).
- Exam reminder: Exam 1 aliphatic amine + HNO2: nitrogen gas bubbles amine carbon ends as an alcohol (school) named test, not a gas-making method
Did you understand this topic?
Your answer is saved with your learning record. It does not mark the topic as mastered.