About ChemQuest Play

How it works

ChemQuest turns chemistry into things you do — predict, test, and reason — not just facts to memorize.

• pH Indicator Lab — read a real household liquid, predict whether it is an acid, neutral, or a base, then drop the cabbage-juice indicator and watch the color reveal its pH. Guessing first — even wrong — is what makes the answer stick.
• Density Tower — stack liquids in the right order, least dense on top and densest at the bottom, and see why oil floats on water: less mass is packed into the same space.
• Titration Lab — predict where the pH will be when the acid is used up, then hold the tap: base runs in and the pH curve draws itself. Stop when the indicator turns. These juice acids are weak acids, so the end point lands above 7, at about pH 8.5 to 9.5 (a strong lab acid giving up the same number of H⁺, drawn dashed for comparison, ends at 7), and the amount of base depends on how much acid is in the flask, not on how strong it is. (A toy model: each juice is treated as a plain solution of its main acid, worked out from its pH.)
• The Sealed Flask — a bottle of vinegar on a scale that reads grams. Predict, then tip in the baking soda: in an open bottle the scale drops by exactly the gas that bubbles away; with the cap on it does not move. Mass is conserved, which is what Antoine Lavoisier showed by weighing sealed vessels. (The plates in his 1789 book were drawn and engraved by Marie-Anne Paulze Lavoisier.)
• Zoom in — after each pH, density or sealed-flask answer, a three-stop dial (Beaker · Particles · Symbols) shows the same moment as particles and then as symbols. Each particle picture is worked out from the station’s numbers and says its scale: pH is ten times more per step, so the window zooms out rather than drawing billions of dots. For lemon juice, vinegar and ammonia it also shows strength: how few molecules of a weak acid split, next to a strong acid at the same pH. The density view draws grams in the same 1 mL box, not molecules, because heavy molecules can mean fewer of them.
• Concept kits — 16 short question rounds, from “what is matter?” through atoms, the periodic table, mixtures, reactions, and pH, up to advanced synthesis.

Our privacy promise

ChemQuest Play is free, works offline, and collects nothing. No accounts, no ads, no tracking, and no data ever leaves your device — your level and days active are saved only in this browser.

Meet the cast

A team of element and bond characters brings chemistry to life — each one stands for how a piece of matter really behaves. Find their illustrated stories on the cast page.

Mistakes are part of it

You never lose anything for a wrong answer. A wrong prediction just explains what really happened and points you to the right idea next time — that’s how real science works.