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Mistake Master · AP Chemistry · Unit 4 · Step-Through Animation

The Equation That Loses an Atom

You'll learnwhy an equation has to show the same atoms coming out as went in, and how coefficients get it there.

Hydrogen burns in oxygen and makes water, so you write H2 + O2 → H2O. Every formula in that line is correct, and the line is still false: two oxygen atoms go in and only one comes out. Twelve short steps; press Next for each one.

12 STEPS · 6 QUICK CHECKS · 2H₂ + O₂ → 2H₂O · v4

atoms in · atoms out · the ledger that has to agree
Before you start
What you're looking at
Hydrogen and oxygen molecules on the left of an arrow, water on the right.
The question
Does the equation as written show the same atoms coming out as went in?
Step 1 / 12