How many moles of carbon dioxide are produced when 4.00 L of propane are reacted at STP?
C3H8 + 5O2 —> 3CO2 + 4H2O

Explanation:

We will need a balanced chemical equation with moles and volumes, so, let's gather all the information in one place.

       C₃H₈ + 5O₂ ⟶ 3CO₂ + 4H₂O

V/L:  4.00

(a) Moles of C₃H₈  

We can use the Ideal Gas Law:

pV = nRT

Data:

p =      1       bar  

V =     4.00 L  

T = 273.15   K  

Calculation:

(b) Moles of CO₂

The molar ratio is 3 mol CO₂/1 mol C₃H₈.

every chemical equation adheres to the law of conservation of mass, which states that matter cannot be created or destroyed. therefore, there must be the same number of atoms of each element on each side of a chemical equation.