Concentrated sulfuric acid – safe dilution, dehydrating and oxidizing properties
ChemistryInorganic ChemistryAges 16–17Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Inorganic Chemistry
Tab one: dilute 98% H₂SO₄ in two ways – pouring acid into water (correct: the temperature rises gradually, read on a thermometer and plotted against the volume of acid added) or pouring water into acid (wrong: the water floats on the acid, boils instantly and makes the acid spatter, with a warning). Tab two: concentrated H₂SO₄ chars sugar into a black, porous column of carbon and releases SO₂; hot concentrated H₂SO₄ oxidizes copper to CuSO₄ and SO₂, while dilute H₂SO₄ does not react with copper.
Lesson: Sulfuric acid and sulfates
What it shows
Concentrated sulfuric acid releases a large amount of heat when it mixes with water, and it is much denser than water. Added slowly to water, the acid sinks and the heat spreads through the whole volume, so the temperature rises gradually; water added to the acid floats on top, boils in the thin contact layer and makes the acid spatter. Concentrated H₂SO₄ is also a dehydrating agent, charring sucrose to carbon, and a strong oxidizing agent because of sulfur in the +6 state: when hot, it oxidizes copper and releases SO₂.
How to use
On the Diluting concentrated acid tab, set the Volume of 98% H₂SO₄ and the Volume of water, choose a Method and press Run (start pouring). Compare the temperature graph and table for the correct method with the warning shown for the wrong one. On the Dehydration – oxidation tab, run the sugar experiment, then heat copper with conc. and dilute H₂SO₄ and compare the gas, the litmus paper and the color of the solution.
Parameters you can change
- Dilution method Pour acid into water (correct), Pour water into acid (wrong – dangerous)
- Volume of 98% H₂SO₄ 5–20 mL
- Volume of water 50–200 mL
- Starting experiment Diluting concentrated acid, Concentrated H₂SO₄ with sugar, Concentrated H₂SO₄ with copper
Questions to explore
- Why must concentrated acid be added to water, and never water to the acid?
- Which two properties of concentrated H₂SO₄ are shown when it reacts with sugar?
- Why does copper react with hot concentrated H₂SO₄ but not with dilute H₂SO₄?
