Carbohydrates: structure, hydrolysis and identification reactions
ChemistryBiomolecules & PolymersAges 17–18
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Biomolecules & Polymers
Choose glucose, fructose, sucrose, starch or cellulose, and the simulation draws the matching number of linked rings (one ring, two linked rings, or a long chain) and shows whether the substance is a monosaccharide, disaccharide or polysaccharide. Choose a reagent (iodine solution, Cu(OH)₂, Tollens' reagent, or hot dilute H₂SO₄) and press Run to see the real result: a blue-black color, a deep-blue solution, a silver mirror, or the chain breaking down into glucose. After hydrolysis, try a different reagent to see the result change completely.
Lesson: Glucose, fructose, sucrose, starch and cellulose: structure, hydrolysis and identification reactions
What it shows
Carbohydrates are grouped by the number of sugar units: glucose and fructose are monosaccharides, sucrose is a disaccharide, and starch and cellulose are polysaccharides of α-glucose and β-glucose. Identification tests follow from structure. Iodine turns blue-black only with starch. Neighboring –OH groups let glucose, fructose and sucrose dissolve Cu(OH)₂ to a deep-blue solution. The silver mirror test detects glucose and fructose, but not sucrose, which has no free –CHO group. Heating with dilute acid hydrolyzes the glycosidic links to give monosaccharides, so the test results change.
How to use
Choose a Substance, then press Run with each Reagent in turn and record the results in a table. Next select Hot dilute H₂SO₄ (hydrolysis), press Run, and repeat the silver mirror or iodine test on the products to see what changes. Move the Temperature slider to show which tests need heating. Finish by asking students to design the shortest sequence of tests that identifies all five substances.
Parameters you can change
- Substance Glucose C₆H₁₂O₆, Fructose C₆H₁₂O₆, Sucrose C₁₂H₂₂O₁₁, Starch (C₆H₁₀O₅)ₙ, Cellulose (C₆H₁₀O₅)ₙ
- Reagent Iodine solution, Cu(OH)₂ at room temperature, Hot AgNO₃/NH₃ (silver mirror test), Hot dilute H₂SO₄ (hydrolysis)
- Temperature 20–100 °C
- Animation speed 0.5–3 ×
Questions to explore
- Why does sucrose give no silver mirror, while the products of its hydrolysis do?
- Which reagent distinguishes starch from cellulose, and what do you observe with each?
- Which structural feature allows glucose to dissolve Cu(OH)₂ at room temperature?
