Law of Conservation of Mass
In a closed system, matter is neither created nor destroyed — the total mass before a reaction equals the total mass after.
Formula
Variables
Example
2 H₂ (4 g) + O₂ (32 g) → 2 H₂O (36 g)
Did You Know?
Antoine Lavoisier established this in 1789 using careful weighing — earning him the title 'father of modern chemistry'.
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More in Scientific Laws & Principles
View allLaw of Definite Proportions
BasicA given chemical compound always contains its component elements in the same fixed ratio by mass, regardless of source.
Law of Multiple Proportions
IntermediateWhen two elements form more than one compound, the masses of one element combining with a fixed mass of the other are in ratios of small whole numbers.
Dalton's Law of Partial Pressures
IntermediateThe total pressure of a mixture of non-reacting gases equals the sum of the partial pressures each gas would exert alone.
Graham's Law of Effusion
IntermediateThe rate at which a gas effuses through a tiny hole is inversely proportional to the square root of its molar mass.
Avogadro's Law
BasicAt the same temperature and pressure, equal volumes of gases contain equal numbers of molecules — so volume is proportional to moles.
Raoult's Law
AdvancedThe vapour pressure of a solvent above a solution equals its mole fraction times the pure solvent's vapour pressure.