Specific gravity is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance.
models do not show every detail
no model can possible explain every detail of a scientific phenomena
<span>CH4 + 2O2-----> 2H2O + CO2
reactants products
Reactants are CH4, O2
Products H2O, CO2</span>
