What relationships can be determined from a balanced chemical equation?

From a balanced chemical equation the relationships of the amount of reactants and products, either as number of units (moles) or as mass (grams), can be determined.

Explanation:

Since reactants combine in a fixed ratio to form a fixed amount of products, the law of mass conservation permits to state cuantitative relationships between the amounts of rectants and products, and this is represented through a balanced chemical equation.

The balanced chemical equation represents the reactants and products using the chemical composition of each substance (consisting of chemical symbols and subscritps)  and shows the relations in which they react or are produced using numbers as coefficients.

For example:

       1 molecule CH₄ : 2 molecules O₂ : 1 molecule CO₂ : 2 molecules H₂O

       1 mole CH₄ : 2 moles O₂ : 1 mole CO₂ : 2 moles H₂O

       16.04 g CH₄ : 64.00 g O₂ : 44.01 g CO₂ : 36.03 g H₂O

        (80.04 g reactants = 80.04 g products)

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.