Gaseous ethane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 16.2 g of ethane is mixed with 19. g of oxygen. Calculate the maximum mass of carbon dioxide that could be produced by the chemical reaction. Round your answer to significant digits.

Answer 1

This is a limiting reagent (LR) problem; we know that because amounts are given for BOTH reactants. I work these the long way because it easier to explain.
2C2H6 + 7O2 ==> 4CO2 + 6H2O

mols C2H6 = grams/molar mass = ?
mols O2 = grams/molar mass = ?

Using the coefficients in the balanced equation, convert mols C2H6 to mols CO2.
Do the same for mols O2 to mols CO2.
It is likely these two values will not be the same which means one of them is not right; the correct value in LR problems is ALWAYS the smaller value and the reagent responsible for that is the LR.
Using the smaller value, convert that to g CO2. g = mols CO2 x molar mass CO2.