🔬 Sciences
Tableau périodique, recherche d'éléments et outils de référence en chimie
Tableau périodique interactif — cliquez sur un élément pour sa masse, son point de fusion et plus
Ouvrir l'outil →Calculez la masse molaire et la composition à partir de n'importe quelle formule chimique.
Ouvrir l'outil →Équilibrez les équations chimiques instantanément avec une explication étape par étape.
Ouvrir l'outil →Convertissez entre pH, pOH et concentration en ions hydrogène.
Ouvrir l'outil →Résolvez C₁V₁ = C₂V₂ pour n'importe quelle variable manquante.
Ouvrir l'outil →Visualisez les configurations électroniques et le remplissage des orbitales pour tout élément.
Ouvrir l'outil →Simulez la désintégration radioactive avec des graphiques interactifs.
Ouvrir l'outil →Chemistry tools for coursework, lab prep and the kind of checking you want before mixing anything. Balancing equations, working out molar masses, diluting a stock solution, reading electron configurations and computing decay.
Formulas come from standard references and the working is shown on the page, which is deliberate — for schoolwork you usually need the method rather than the answer, and for lab work you should be verifying rather than trusting.
Which tool do I want?
| If you… | Use |
|---|---|
| You need coefficients for a reaction | Équilibreur d'équations |
| You are looking up an element or a periodic trend | Tableau périodique |
| You need molar mass for a compound | Constructeur moléculaire |
| You are diluting a stock solution | Calculateur de dilution |
| You need pH, pOH or hydrogen ion concentration | Calculateur de pH |
| You are working with a radioactive sample | Simulateur de demi-vie |
| You need the electron configuration of an element | Configuration électronique |
C1V1 = C2V2 tells you the volume of stock, not the volume of solvent
The commonest dilution mistake is arithmetic that is right and a procedure that is wrong. Solve for V1 and you get the volume of concentrate to take. The solvent you add is V2 minus V1 — the difference, not V2.
In practice you rarely measure the solvent at all. You take V1 of stock, put it in a volumetric flask, and top up to the V2 graduation. Dissolving changes the total volume slightly, so measuring the two separately and adding them does not reliably land on V2.
One safety point that is not arithmetic: when diluting concentrated acid, the acid goes into the water, never the reverse. The mixing is strongly exothermic, and adding water to concentrated acid can boil it and throw acid out of the vessel.