๐Ÿงชap chemistry review

Law of Definite Proportions

Written by the Fiveable Content Team โ€ข Last updated August 2025
Verified for the 2026 exam
Verified for the 2026 examโ€ขWritten by the Fiveable Content Team โ€ข Last updated August 2025

Definition

The law of definite proportions states that a chemical compound always contains exactly the same proportion of elements by mass.

AP course connection

Topic 1.3: 1.3 Elemental Composition of Pure Substances

Unit 1

"Law of Definite Proportions" also found in:

2,589 studying โ†’