the molar mass of propane is 44.1 g/mol. what mass of water in grams is formed from the combustion of 1.85 x 10^-5g of propane

Question

the molar mass of water is 18.01 g/mol. the molar mass of C3H8 is 44.1 g/mol.  what mass of water in grams is formed from the combustion of 1.85 x 10^-5g of C3H8

Answer 1

Stoichiometry is best solved using the factor label method.  This is best done by letting the units guide you through the problem.  Set the problem up to let the units cancel until you are left with what you are looking for in the numerator.  Below is how to set up the problem.  It is easier to solve if the problem is written using two lines. 

 

? g water=(1.85×?10?^(-5) g propane ) ((1 mol)/(44.1g propane )) ((18.01g water)/(1 mol))

 

Every "factor label method" problem is set up with what we are looking for set equal to the given amount in the problem multiplied by conversion factors to lead the units so we are left with the units of what we are looking for in the numerator.