Ch ChemAI

All experiments › Acids, bases and salts

Making a salt: copper(II) sulfate crystals

React an insoluble base with an acid, filter off the excess and crystallise the salt.

Topic: Acids, bases and saltsGrade: 10Free

🧪 Start the experiment — free

Runs in the browser on phones, tablets and computers. No sign-up needed. For teachers: assign any experiment to a class, see results and calculations.

What you do

  1. Heat the acid gently and add copper(II) oxide until some black powder stays undissolved (excess). Speed ×5 helps.
  2. Stop heating. Press “Filter” on the beaker, then click the evaporating dish. The black excess stays in the filter paper.
  3. Heat the dish (speed ×20) until crystals appear at the edge, then stop heating.
  4. Let it cool: more blue crystals grow. (Heated to dryness they would turn white.)

Safety in a real lab

⚠ Hot acid: goggles. Never heat the dish to dryness — it spits.

More experiments on this topic

Neutralisation with an indicatorTurn a pink base colourless by adding acid, and watch the temperature rise.Red-cabbage rainbowA natural indicator shows a different colour at every pH.Strong and weak acidsSame concentration, very different behaviour.Making a salt: copper sulfateBase + acid → salt + water, with copper(II) oxide.The hydrogen balloonCollect the gas from a metal and an acid in a balloon — then light it.pH titration curveAdd acid from a burette and draw the S-shaped curve.