Joseph Louis Proust (1754-1826), In 1799 Proust stated that "Compounds always contain the same elements in a constant proportion by mass." This statement is now called law of definite composition or the law of constant proportion.
John Dalton (September 6 1766 - July 27 1844)
John Dalton
Think of it in terms of a scientist performing a lab experiment. He/she will need to know the specific amounts of substance required to obtain the desired reaction. The law is fundamental for stoichiometry operations.
Each atom of a particular element has a constant (average) weight, and in chemical reactions, the numbers and types of atoms in the reactants must be the same as the numbers and types of atoms in the products. This explains the law of the conservation of mass. Each molecule of a compound or polyatomic element is composed of a fixed number of one or more particular kinds of atoms; this explains the law of constant composition.
Each atom of a particular element has a constant (average) weight, and in chemical reactions, the numbers and types of atoms in the reactants must be the same as the numbers and types of atoms in the products. This explains the law of the conservation of mass. Each molecule of a compound or polyatomic element is composed of a fixed number of one or more particular kinds of atoms; this explains the law of constant composition.
What is a substance with constant composition
"In chemistry, the law of definite proportions and also the elements, sometimes called Proust's Law, states that a chemical compoundChemical_compoundalways contains exactly the same proportion of elementsChemical_elementby mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition." - Wikipedia
No,Law of constant composition is valid only for compounds made from the specified isotopes of the element.
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That is the law of constant composition.
The law of constant composition for compounds is a law in chemistry according to which any given compound always contains the same component elements in the same ratios, by mass. The ratios do not depend on where the compound comes from or the way in which it was produced.
A piece of evidence that is commonly used to prove the law of constant composition is that any sample of water is 88. 71 percent oxygen and 11. 19 percent hydrogen. It was formulated by Joseph Proust.
He would insist that all Carbon Dioxide molecules have the same composition, by his Law of Constant Composition.
In water, there is always 8 times the mass of oxygen than there is of hydrogen.
It means that in any pure compound, the proportion of constituent elements (by mass) is a constant. This allows their chemical formulae to be determined.
The law of inertia (or newton's first law) states that a body remains stationary or moves with constant velocity if the net force that acts on it is zero.
Think of it in terms of a scientist performing a lab experiment. He/she will need to know the specific amounts of substance required to obtain the desired reaction. The law is fundamental for stoichiometry operations.