Chemical Equation Helper
Mass is conserved in any chemical reaction — this checks whether a reaction's measured reactant and product masses actually balance, and calculates the practical yield percentage if they don't match exactly.
Inputs
Result
Unbalanced by 2 g
Yield 98%
How the chemical equation helper works
The difference between reactant mass and product mass is checked — if it's effectively zero, the reaction is considered mass-balanced.
Yield percentage = (product mass ÷ reactant mass) × 100, giving a practical sense of how much mass was actually converted versus lost.
Worked example: 100 g of reactant producing 98 g of product
- Difference = 100 − 98 = 2 g, so the reaction is reported as 'Unbalanced by 2 g' — some mass is unaccounted for in this simple check.
- Yield = (98 ÷ 100) × 100 = 98%.
Common mistakes to avoid
Assuming an 'unbalanced' mass result means the law of conservation of mass was violated
In practice, an apparent mass discrepancy almost always reflects incomplete measurement (a gas product escaping unmeasured, residue left in equipment, or measurement imprecision) rather than an actual violation of a fundamental physical law — mass really is conserved overall, even when a specific lab measurement doesn't perfectly capture every product.
Confusing this simple mass-balance check with formally balancing a chemical equation
This tool checks whether measured masses are consistent with conservation of mass; formally 'balancing a chemical equation' means adjusting stoichiometric coefficients so atom counts match on both sides symbolically — a related but distinct chemistry skill this calculator doesn't perform.
Frequently asked questions
Why might real reactant and product masses not match exactly even in a correctly performed reaction?
Common real-world reasons include a gaseous product escaping without being captured and weighed, small amounts of product lost during transfer or filtration, or simple measurement imprecision — the underlying law of conservation of mass isn't actually being violated in these cases.
What does the 'yield' percentage shown here actually represent?
It's the practical ratio of product mass recovered to reactant mass used — a simplified efficiency indicator, though the more standard chemistry concept of 'percent yield' (actual versus theoretical yield) is covered more precisely by the dedicated Percent Yield Calculator.
Is this the same as writing and balancing a chemical equation symbolically?
No — this checks numeric mass measurements from an actual or hypothetical reaction; symbolically balancing an equation (like 2H₂ + O₂ → 2H₂O) is a separate process involving adjusting coefficients so atom counts match, which this tool doesn't perform directly.
Why does conservation of mass matter as a foundational chemistry principle?
It reflects the fact that atoms are neither created nor destroyed in an ordinary chemical reaction — they're only rearranged into new molecular combinations, which is why the total mass before and after a reaction (accounting for every reactant and product) should be equal.
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