Reaktiomassa

Reaktiomassa is a term used in chemistry to describe the total mass of substances that participate as reactants in a chemical reaction. It is the sum of the masses of all reactants present at the start of the reaction, and it may be relevant in stoichiometric calculations, reactor design, and process accounting.

In a closed or batch system, the reaktiomassa is linked to the law of conservation of mass: the mass of reactants equals the mass of products, assuming no mass leaves or enters the system and no mass is converted to energy in a way that would affect mass accounting. When catalysts are present, their mass is typically not counted as part of the reaktiomassa if they are not consumed in the reaction. If gases or liquids are continuously removed or added, the reaktiomassa refers to the mass bound to the defined system boundaries at the start.

Calculation of reaktiomassa involves summing the masses of all reagents used. For a reaction described by A + B → products, the reaktiomassa is the mass of A plus the mass of B. If multiple stoichiometric steps are involved, each reactant’s mass is included according to its presence in the feed or the reaction mixture.

Example: methane combustion CH4 + 2 O2 → CO2 + 2 H2O. The reaktiomassa for the reactants is the mass of CH4 plus the mass of 2 O2 (for a given amount), e.g., 16 g CH4 and 64 g O2, totaling 80 g. The products together also amount to 80 g, illustrating mass conservation.

Applications include process mass balance, yield calculations, and scale-up in chemical engineering.