‹ Chemistry simulationsChemistry · A Level 9701 · 34 Nitrogen compounds (A Level)Six simulations covering Topic 34: why ethylamine is a stronger base than ammonia and phenylamine a weaker one, with the lone pair drawn in 3D; making phenylamine from nitrobenzene with tin and hydrochloric acid, and testing it with bromine water; the two-step route to an azo dye, with a temperature slider that shows why diazotisation must stay below 10 degrees; making amides from acyl chlorides and what happens when they are hydrolysed or reduced; how an amino acid changes charge as the pH changes; and how peptide bonds form, break, and how electrophoresis separates amino acids.
A base accepts a proton using the lone pair on nitrogen, so the question is always how available that lone pair is. In ethylamine the ethyl group pushes electron density onto nitrogen. In ammonia nothing pushes or pulls. In phenylamine the lone pair is drawn into the benzene ring and shared out over it. Pick each one and compare the lone pair.
Phenylamine is made by reducing nitrobenzene. The mixture is heated under reflux with tin and concentrated hydrochloric acid, which gives the salt, and then sodium hydroxide is added to set the free amine loose. Step through the bench, watch the molecule underneath change, and finish with the bromine water test.
First phenylamine is turned into a diazonium salt with nitrous acid, which has to be kept cold. Then the diazonium ion is coupled to phenol in alkali to make a coloured azo compound. Set the temperature, step through, and see what happens if the first step is allowed to warm up.
An acyl chloride reacts with ammonia or an amine to give an amide. Once made, an amide can be split by acid or alkali, or reduced to an amine. And although it has a nitrogen with a lone pair, it is not a base: look at what has happened to that lone pair.
An amino acid has an acidic group and a basic group, so what it carries depends on the pH. Drag the pH slider and watch the same molecule gain and lose protons. At one pH, the isoelectric point, the molecule is a zwitterion with no net charge.
Two amino acids join by a condensation reaction that makes a peptide bond and loses water, and the order matters. Boiling with acid splits the bond again. Then use an electrophoresis strip to separate a mixture of four amino acids: set the pH and see which way each one is pulled.
Six interactive simulations for Cambridge A Level Chemistry 9701 topic 34 Nitrogen compounds: a 3D comparison of the base strength of ethylamine, ammonia and phenylamine with the lone pair delocalised into the benzene ring, the reduction of nitrobenzene by tin and concentrated hydrochloric acid to phenylamine and the bromine water test, a two-step 3D route from phenylamine to an azo dye with a temperature slider for the diazonium salt, the formation of ethanamide and N-methylethanamide from ethanoyl chloride with their hydrolysis and LiAlH4 reduction, glycine and alanine zwitterions against pH with the isoelectric point, and dipeptide formation, hydrolysis and electrophoresis of amino acids.
Six simulations covering Topic 34: why ethylamine is a stronger base than ammonia and phenylamine a weaker one, with the lone pair drawn in 3D; making phenylamine from nitrobenzene with tin and hydrochloric acid, and testing it with bromine water; the two-step route to an azo dye, with a temperature slider that shows why diazotisation must stay below 10 degrees; making amides from acyl chlorides and what happens when they are hydrolysed or reduced; how an amino acid changes charge as the pH changes; and how peptide bonds form, break, and how electrophoresis separates amino acids.
Nitrogen compounds (A Level) is a free, browser-based simulation for Cambridge International AS & A Level Chemistry 9701 (topic 34 Nitrogen compounds). The course is assessed in Paper 1 (Multiple Choice (AS)), Paper 2 (AS Structured), Paper 3 (Advanced Practical), Paper 4 (A Level Structured), Paper 5 (Planning, Analysis, Evaluation). Syllabus for examination in 2025-2027. There are 6 tabs, each a self-contained experiment with its own controls and live readings, and nothing to install: it runs on a laptop, tablet or classroom projector.
Full syllabus map: A Level Chemistry 9701 topic 34.
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