What is another word for doctrine of definite proportion?
Pronunciation: [dˈɒktɹɪn ɒv dˈɛfɪnət pɹəpˈɔːʃən] (IPA) 
The "doctrine of definite proportion" refers to the principle of chemistry that in a given chemical compound, the ratio by mass of the elements present is always the same, regardless of how the compound was prepared. Some synonyms for this concept include the "law of definite proportions," the "principle of definite proportions," or the "constant composition law." These terms all describe the same basic idea that the composition of a chemical compound is fixed and constant, and that the proportions of the elements in the compound are always the same. Understanding this principle is essential for many areas of chemistry, from measuring reactions and determining compositions to predicting reaction outcomes and designing new materials.
